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By Master Tamlene ap
Guidgen
Craftsmanship can be defined in
a lot of ways. A fairly common usage includes the
statement do your
best work in all tasks”. Something that is often
misunderstood in this statement is the difference between
doing your best and perfectionism.
Doing your best means that you must reach
a compromise between your absolute best work (which takes a very long
time), and work which is of good quality but still allows you to get something
done. Almost everyone errs on the side of trying too hard to do
perfect work, and thus getting very little done. Perfectionism includes
the work which commonly graces the covers of magazines like Fine Woodworking.
Work like this is something to aspire to, and be inspired
by. It takes a huge amount of experience to do work of
Fine Woodworking caliber.
It is very important to include
the amount of work you get done in any estimate of how close you are to
“working at your best”. If you only do one piece each year,
your abilities will not improve very
much. Twenty shoddy pieces each year
will also not improve your
abilities much. Neither case is “working at
your best”. You must strike a balance, and
realize that medium quality work actually represents your best
work in the long run.
Do not be a slave to your
ruler. Measuring things as a specific
number of inches is a fairly modern concept, and
can take over a project unnecessarily. What usually
matters more than inches is
proportion. Sometimes there is
important dimensionality, but what counts is that
something fits, not that it is so many inches. I often
measure in hand spans. If you want
accuracy, you can mark the dimension carefully
on a piece of scrap. For proportion, a pair of
dividers works well to pace off the work. Rulers are
useful things, but please keep an open mind and avoid being
compulsive about them.
Power tools are very oversold. Also
oversold is sand paper. Both are extremely useful in
their place, but in a home workshop their place is limited.
Hand tools are generally faster,
have fewer health hazards and are much more pleasant to work with than power
tools. In order to know the truth of what I am saying, you must be willing
to work with a hand tool long enough to gain some proficiency
with it. Only after some mistakes and slow work will you begin to
see the efficiencies inherent in a given hand tool.
Power tools can speed up
repetitive work. Very little of what is done at home is
repetitive enough to justify the time spent setting up
a power tool and cleaning up the amazing
mess afterward. Also not
justified is the noise and dust, and
the sheer amount of space occupied
by power tools. I own many, and speak from experience. I only use a few.
There is another aspect of hand
tools which is really nice. Hand
tools give you the option of spending
money to acquire them, or spending
time to make them. Most any hand tool can be made for almost
no monetary expense. If you don’t believe
me, come to Unser Hafen Blacksmithing Guild
some time. We’ll make you some tools.
Some tasks are repetitive enough
that power tools make sense. Rip sawing (reducing the width of a long
board) is really a lot of work and not terribly entertaining. Rip
sawing is very sensibly done with power tools in these days of no
apprentices. Surface planing of rough lumber is also sensibly done with power
equipment.
Surface smoothing for finishing
is not a good use for sand paper. Most
surfaces are much better attacked with
a hand plane and a
scraper. To make a coarsely smoothed surface very smooth takes
a lot of time with sand paper (power or hand sanding). A plane and a
scraper do the job quite quickly. As a surface gets more curved, or
smaller, planes and scrapers make less sense and sandpaper makes more.
Introductory
Woodworking
If you sweep the floor clean
before you start, and throughout your work, it is much easier to find pieces of
wood which accidentally chip out that were not supposed
to be removed. The piece can easily be
glued back with either yellow wood glue or cyanoacrylate glue, with
none the wiser.
1.
Marking accurately and squarely
Making wooden joints often
involves careful marking of your piece of wood. If your marks are
not in the right place, you have no hope of sawing or chiseling accurately. You
rarely need to mark a specific distance on a board—rather,
you may need to mark an identical distance
(however long) on two boards. The tool used
for this task is a marking gauge. It consists of
a sharp point attached to a stick. The stick
is in turn held by a block of wood
(fence). The mark is made by putting the fence against
the edge of the board to be marked and scoring
the surface of the board with the
sharp point. The distance between the
fence and the sharp point is adjusted by a clamp which
holds the stick to the fence.
Another type of mark you need to
make is a mark perpendicular to one edge of a piece of
wood. To do this, you need an accurate square (you also
need a nice straight edge on the wood, discussed
later). You can buy a good square, or make a cheap one accurate by
adjusting it. A good test for a square (and also for your
marking ability) is to draw a line
around the entire circumference of a board
perhaps three or four inches square. Does
your line meet the starting place exactly?
How you make a mark can also affect
accuracy. A pencil line, even a fine one, has a lot more
error in its width than most wooden joints will tolerate. There are
two ways around this error. One is to use a knife edge to scribe a
very fine line, and then work carefully to this line. The other way
is to use a pencil line, and then fit two pieces to each
other (and promptly mark them unambiguously
as belonging to each other). Either way works
well, although if you use a pencil, it should be a fine one.
2.
Cutting to a line
First, start with sharp tools.
You cannot cut accurately (hand or power) with dull blades. See the appendix.
Whether you are cutting with hand or power
tools, watch the wood and the mark, not the
blade. Making an accurate cut requires practice and attention. A saw cut needs
to start straight. You cannot force the saw direction without ruining your
accuracy. Cutting straight is easy when you start straight.
You can avoid cutting
past your stop line if you realize that it is not
necessary to cut all the way to it. You only need
to cut to within one saw kerf of the stop
line. When all sawing is done, clean up the tiny bit
remaining in the corner with a chisel.
Starting a cut with a
hand saw is sometimes a bit tricky. At
first, the saw will sometimes jump and shudder
everywhere except at
your mark. This is typically caused by either using too
coarse of a
saw for the hardness of the
wood, using the wrong type of saw
(crosscut vs. rip) or putting pressure on the saw. Even after a cut is
started, you will get the most accurate cut if you
let gravity feed the saw. If you should end up
having started the cut slightly in the wrong place, instead of
trying to force the saw to your will, lay the
saw down almost flush with the
surface and gently broaden your starting cut
until you can saw in the correct place.
3.
Planing a straight edge
You can plane a much
better straight edge by hand than with a
power jointer or router. To do this, you need
the longest (sharp!) hand plane you can find. I use a No. 8 jointer
plane, which is about 24 inches long. You must have some
arrangement for holding the board to be planed without requiring any
attention from you. Your cuts will not be true
if you have to hold the board with your elbow and knee
while you plane. At the start of a cut, push down on the front of
the plane only. At the end of the cut, push down on the back of the
plane only (at the handle). Think
of your action as trying to plane a concave
edge, and you will end up with a straight
edge. Eyeball the edge when you are done—it should be
absolutely straight after only a little practice.
If it is important to
have the edge exactly at 90 degrees to the face, lay the
board on it’s face, spaced about 1/8” above the
bench. Now lay the plane on it’s side, and plane the edge. If you do
a lot of this, you should build a fixture for
it so that you don’t wear a groove in your
workbench.
4.
Gluing up boards
Spend a lot of time before you
apply glue arranging your boards so that matching edges end
up next to each other. Mark adjacent edges
(and front/back) so you can find the arrangement again. If you
choose and arrange your boards carefully, most people will not
realize that your nice wide board is glued up from smaller ones.
To glue two edges together with no gaps, the
edges both need to be absolutely straight, and at complimentary
angles to each other. The edges do not need to be at 90
degrees to their faces. To joint two boards to
match, lay the boards next to each other on the bench in the
preferred final orientation. Now pick them up, and fold
them as if there is a hinge joining them. Clamp them in your vise
this way; back to back or front to front. Now joint the edge. If
your planing results in a nice straight edge which is a
bit off of 90 degrees, you will still have a
flat panel when gluing is done since the errors in the
two boards will cancel each other.
If you are forced to close gaps between
boards with a lot of clamp pressure, something is wrong. If you have done your
edging right, you should be able to apply glue to the
edges, push and wring the edges together and get them to
stick to each other with no clamps, just the surface tension of the
glue. Try it some time, it is a lot of fun.
Don’t use an
excessive amount of glue. Some
books and articles will admonish you to “get
the right amount of squeeze out” when you
clamp. The right amount of squeeze out is none. You do
need to make sure glue coats the entire edge (both pieces!), so in
practice you get some squeeze out. The ideal would be to have glue
just come up to the edge and no farther. When you apply
glue, make sure it covers each edge completely, in as
even and thin a layer as you can.
I usually space my clamps between one and
two feet apart for edge gluing ¾” thick stock. It is nice
to have more clamps than you think you need in case a problem comes up when you
are clamping. Alternate the clamps top and
bottom to keep the surface flat. With one inch and
thicker stock, you can get away with a lot in terms of
clamp spacing and uneven pressure between
clamps if your edges mate nicely. When edge gluing
½” and smaller, you must be very careful to
get even clamping pressure. Tighten the clamps little by
little, so that they all reach final pressure together. As you
tighten, check the face for flatness, to make sure you are not
introducing a cup into the panel.
Take great care in making the
faces of your boards all lie in the same plane. This
can save you a tremendous amount of work later. If you tighten your
clamps little by little, it is much easier to adjust the edges. If
you adjust the edges with the clamps too tight, you will introduce a bend in
the board. If you have a hard time with this, or have a
panel which must end up with a really flush surface, invest in a
doweling jig, and put dowels in to align the edges.
5.
Planing end grain
A block plane is specially
designed to be able to plane end grain. If your plane is very
sharp, and you take a nice thin cut, end grain
is fairly easy to plane. Be careful at the far
end of the board, however, as it is
easy to tear a huge chunk off of the edge. You can either plane both
ends against the middle, or else clamp the board to be planed firmly
up next to a piece of scrap to support the
far edge. Sanded end grain looks nothing like planed end
grain.
6.
Avoiding cross grain construction
When two pieces of
wood are attached rigidly to each other, and the grain
on one piece is perpendicular to the grain on the other, a
split will inevitably develop with time. Wood
expands a lot more perpendicular to the grain
than parallel to the grain.
A lot of period chests are made with cross
grain construction, and have the splits to prove it. A lot of known world
workmanship also has cross grain construction, and will either split or come
apart at the cross grain joints in
time. A common chest design in the current
middle ages has grain running horizontally front and back, with
grain running vertically on the end pieces (which extend below the bottom of
the chest as legs).
There are
three reasons for building
chests with cross grain
construction—ignorance, “its period”, and
expediency. I feel that only the first reason is valid.
The second reason is not valid—there are many period examples of
chests with no cross grain construction, including
properly constructed cases and also frame and panel. The
third reason is quite questionable in
my mind. If you are not
interested in your work lasting, then you must have
quite different motives from my own.
7.
Sharpening
If you want to risk your tools,
you can try using a high speed motorized grinder. Several
things can improve the risk:
·
slow the grinder down to 1725 rpm
·
get “cool” type grinding wheels
·
back the blade you are
sharpening with a larger piece of
metal (a heat sink). Before grinding, dip the
assembly in water. The water wicks up between
the two pieces of metal ensuring good thermal contact.
A much better choice is a hand
powered grinder—not because of any hand tool mystique, but because
it is extremely difficult to overheat your tools with a hand grinder.
Either of the above methods should give you
a hollow ground edge.
Use either a small square or a sharpening
jig to check your edge accuracy
Before you can sharpen the edge
you rough shaped, you must polish the back of the blade. You need to
gradually move to finer and finer abrasives in the polishing process. I follow
any rough grinding with a fine Carborundum stone (“India”
stone), followed by a Washita stone. If the tool
is a particularly nice one I end up on a “Soft Arkansas” stone. There
are at least two finer grades than “Soft
Arkansas”, but I have
not found them to noticeably improve matters
in general woodworking.
The back should be very flat and shiny when
you are done. Only when the back is polished does it make sense to
fine sharpen the edge of the blade. You only need to get
the tip of the hollow ground edge sharp. Now you can proceed to sharpen the
hollow ground side.
When you sharpen a blade, hold
it very near the edge, and move the blade in small circles. You will have much
better control of the blade angle.
8.
Sanding
A lot of the
time, sanding makes some sense. Surfaces which have
grain pointing different directions (such as curves) can
be insanely difficult to work with edged tools. Flat surfaces are very efficient to smooth
with a plane after you have some practice in its use. If
you have never used a plane, get a small block
plane, read about how to use it and use it for a bit on
every project you make. Using a plane without any experience
and not using sandpaper at all will slow you down a
lot. Get some woodworking done while you gain planing experience
gradually.
Sanding
is most effective if you
start with a coarse enough
abrasive. Your abrasive must be almost as coarse as the irregularities in the
surface. Typically, start with 80 grit paper (60 grit
if you are trying to remove a bunch of
wood). 80 grit paper is good for
removing typical power tool marks, like a machine planed
surface. If you want your surface to stay flat, wrap the sand paper
around a flat block rather than holding the paper in your hand. Sand
all areas which need it with #80 before changing grit size.
The largest jump in grit size
you should make is about 1.5 times as fine. If you
started with #80, your next choice should be no finer than
#120, followed with no finer than #180, etc. If you take
larger steps, it will make your sanding take a lot longer. At each
grade you use, be sure to sand all of the areas you
sanded with the previous grit. Work in high
contrast lighting, like direct sunlight, so that
you can see the scratches in your work from the
previous grit. Take them all out before going to a finer
grade. If scratches show up after
you start on a new grit and don’t
sand out quickly, you should consider going
back to a bit coarser grit for a while.
For
everyday projects, you can stop at #150 or
#220. There is little point in
using any finer grits on items
you plan on taking camping with you. For
surfaces you want smoother that are made of harder woods,
it can make sense to go all the way up to #600.
9.
Finishing
I don’t know a lot
about finishing, so I use a couple of easy
methods, oil finish and varnish.
Oil finish brings out a lot of
inherent color in the wood, and is available in ‘natural’ and
various stains. A couple of good brands are Watco and Deft. Read the
directions! I do not recommend linseed oil or dried linseed oil, as they take a
lot longer to dry.
Oil finishes can be enhanced by
applying a wax after they are quite dry. You need a
wax intended for the purpose that is compatible
with an oil finish. Watco makes a wax specially made
to work with their oil. I haven’t done much of this, but
it can be very pretty.
Varnish
provides much more protection
to the wood than oil.
Varnish soaks into the wood and
hardens, making the wood surface much more tolerant
of abuse. Most varnishes also provide much more
protection against water than an oil finish. If your wood will spend a lot of
time in sunlight, get a polyurethane varnish for outdoor use.
The
difficulty in using varnish
lies in not getting little
hardened drips of varnish at the bottom edge of
your piece. Varnish also takes the patience to
apply several coats. I use Last and Last
brand primarily because we have some left over from when
we did our wood floors. Read the directions!
It is
very important to read the directions on
finishes. Especially Important is the fire danger which finish saturated rags
or paper towels represent. As the finish dries, a small amount of heat is
generated. If the heat is confined, like in a wadded up
towel in the trash can, the material can
spontaneously combust hours later. I throw my
finish rags in the wood stove. I prefer
a satin finish to a gloss finish. Try both, and see what you like.
Cutting
dovetails
Dovetail joints are really fine
things. They are both esthetically pleasing and amazingly strong at
the same time. Mortise and tenon joints are
strong, not much easier than dovetails, and when
you are done, no one can see all of your work! Dovetail joints have a bit of terminology
associated with them. One side of the joint is
called the tail, because the fan shape is
reminiscent of a spread dove’s tail. The other side of
the joint is called the pin (why I
have no idea). Be careful as some authors
reverse this.
1.
Stock preparation
Leave your stock long while you prepare
one edge. Taking all of
the pieces out of one board is a smart
idea, as they will match better. Make
one edge of your board absolutely straight with a long
plane. This edge will end up as the reference
edge from which all measurements and
alignments are made. Leave the other edge rough so that the
difference is obvious.
Using an accurate square, draw lines perpendicular to your
reference edge to mark out the lengths of wood
you will be using. Remember that your
saw cut has width, and keep the saw in the same place in
relation to your line. Either cut on one side of the line, or down the middle
of the line, but do the same thing the entire length of the board.
Do not cut your stock to final size. Allow
yourself some room. The pins and tails of your joints (on each end of the
board) should be perhaps 1/32” extra long, so that when
the joint is assembled a bit extra sticks
out. This allows you to end up with
a flush surface (by planing away the excess), rather than a sunken
one. You should also expect to do some finish planing on the other
edges, those not involved in a joint.
The edges
of your boards should be
cut square and even. Any wavering
in the edge, especially in the end grain, must be allowed for
when you mark your stock so that you don’t end
up with a recessed
tail. If the end grain is not square
to the edge you may have such misalignment
that it will be impossible to assemble all
four corners at once.
Check
your pieces after you cut them with a square
and straightedge. If the end grain is not square to the reference edge, or if
your cut wavers, it is usually a lot easier to plane the end smooth and square
now. You should also compare sizes on pieces which need to match
each other. I often plane two pieces at once in the vise so that they are
exactly the same size. If they are not the same size, your box will be
trapezoidal instead of rectangular.
Mark the orientation of your
boards if it is important (mainly for appearance). You will have a
hard time figuring it out later.
2.
Marking
Set your marking
gauge just a bit more than the thickness of the
boards you are using (1/32” or so). Lightly
score the boards to be
dovetailed together, along the edges to be
joined. I usually score
face, back, and edges for each board
in each joint. These marks indicate the
edges of the pins and tails. The marks also show where the inside edge of the
board forming the other half of the joint lies. If your marks do not
end up straight lines, your finished assembly will show gaps along this edge.
3.
Cutting tails
You must have very good lighting
to cut dovetails. You must have light down on your bench
for marking and measuring. You must also have light from the side (or below) so
that you can see while sawing. Get a lamp which you can place where you need it
and you will save lots of frustration and squinting.
There are a lot of
sequences which work in cutting dovetails. I like to cut
the tails first, but it also works to cut the pins first. Begin by deciding how many dovetails you are
going to put in an edge, where they will go, and how big
they should be. Some of the considerations follow:
If you space your dovetails
unevenly (as I almost always do), put them near the high stress
points. In a box, the stress is mostly along the top and bottom, especially the
top edge.
Evenly spaced
dovetails, especially with pins and tails the same size,
is what you get out of a dovetail template. Why try to imitate a
router? This is kind of a modern argument, one that
didn’t occur to people in the middle ages.
At the edges of your joint, there will
typically be either half of a tail or pin. Half of a pin is stronger than half
of a tail, and a better choice.
I usually mark the centers of
the tails first, once I have decided on a layout. In marking the
tails, please note that accuracy is not critical. The
pins will be sized to fit the tails by marking them from the finished tails.
Whatever angles, size and spacing your tails end up with, your pins will be cut
to match.
If your tails have identical
spacing on two or more corners, it is a lot easier to mark the locations on a
piece of scrap and transfer the marks from the scrap to both corners. This
greatly reduces mistakes and speeds up the work.
Use a pencil to mark the
tails. With ring-porous woods like oak,
it is easy for a knife mark to get lost in the
grain. Also it is
difficult to draw a straight line not quite in line
with the grain using a knife blade. The grain pulls the
knife off of the line you are trying to draw.
Draw the tails using
a bevel gauge. I set mine to an angle of about
1:6 (1 over and 6 up). People seem to use a variety of
angles, including 1:8 and 80 degrees. Draw the tails between the
scribed line and the end of the board. Now go along the edge and X
out all of the pieces which are to be removed (in pencil). Look
carefully at what you have
drawn. Did you really cross out the scrap, not
the good parts? Are you tails drawn right, or are they reversed? Look
carefully, this is easy to mess up!
Using a small square, extend
the lines you have drawn straight down the end grain
across the thickness of the board, marking each side of the tail.
Put the piece of wood in a
vise, edge up. Start sawing along the mark in
the end grain until you have a shallow groove. Now rotate
the saw so it is pointing straight up and down and make a shallow groove along
the face of the board. Now angle the saw more and more, joining the
two saw marks you have made along the diagonal.
Be careful not to cut beyond the scribed line
on the face of the board. By working
back and forth along these grooves, you can guarantee
that the cut
will be in the right place when it comes out
the far side of the
board. This is a good thing to practice a lot
on scraps of wood, either making square or
angled cutoffs. Remember not to force the saw.
Saw
carefully along the pencil
lines, on whichever side you
choose, not quite up to the scribe line. Once the cut is
deep enough that the saw is self guiding, bring the saw
horizontal and saw down
almost to the scribe line. Check both sides of
the board as you approach the
scribe line so that you don’t unknowingly saw past the
line on one side of the board.
Since you are going to use the tails to mark
the lines for cutting the pins, the
size of each tail is not critical. This is, however, an
excellent chance to practice your sawing to a line. Now you
need to remove the waste from between your saw cuts.
Before you start, once again
examine your X’s marking the waste pieces to be removed. Are you sure they are
in the right place? You can use either a fine turning saw or a chisel for
rough stock removal. I use a mortising chisel.
The type
of chisel you use
for rough stock removal is not
critical, as long as it is narrow enough so
it doesn’t score the inside edges
of the tails. Your chisel must also be tough enough to
deal with rough stock removal. Many bevel edge chisels
will chip if you use them for chopping.
Each time you start work in a
new spot, ask yourself if that spot is really waste
material. Every time you pick up the
board you are chiseling on, you must clean the
area underneath it. A small chunk of wood can make a nasty dent in the surface.
First remove most, but not all of the waste.
Leave a bit of waste, maybe 1/16” in front of the scribe
line. Chisel down onto a piece of scrap on your workbench so that
you don’t cut into your bench. Chop down, and then chip out the part you have
cut through (from the end grain). Proceed like this at least halfway
through the wood, and then turn
the board over and finish the cut from the
other side.
Now move your chisel
to the scribed line. For this cut you might want to
sharpen your mortise chisel or use a bevel chisel. Tap the chisel
gently with a mallet to set it in
the line, and then tap a bit harder
until you are about halfway
through. Do the same thing from the other
side and you are done removing the
waste.
Your chisel needs to be either exactly
perpendicular to the board, or at an angle which will give you more clearance
in the middle of the cut, not less clearance. When the joint is
assembled, you will not be able to tell if you have undercut the
middle part of the tail. Waste left in the middle results in
unsightly gaps after assembly.
Take the time now to trim up the
sawn edges of your tails with a chisel. The edges don’t
need to be perfectly smooth, but they should be pretty straight. A
fine saw or a knife can also be useful. If any of your tails ended up with wavering
edges, straighten them up now.
4.
Cutting pins
When you cut the
tails, you were cutting at an angle to the grain in the wood.
Cutting the pins is directly along the grain. This can be a
problem, especially if you are using one of the very
fine Japanese pull saws. To see why, you need
to understand the difference between rip saws and crosscut saws.
When you are cutting across the
grain, the smoothest cut will be had with a saw whose
teeth are shaped like tiny knives. This type of saw will cleanly
sever the wood
fibers. Crosscut saws have teeth
shaped like knives.
When you are cutting with the
grain, a different shaped tooth is needed.
. If your saw teeth are knife shaped (crosscut), the saw
is going to follow the wood fibers. To allow the saw to be
guided, a chisel shaped tooth works best. Saws with
chisel shaped teeth are called rip saws. When you cut the pins, you are cutting
in the same general direction as the grain, but probably not exactly the same.
Japanese back
saws have teeth which are extremely knife shaped. This
makes them very difficult to guide in cutting pins. (There
is a type of Japanese saw intended for ripping, but it is not very
common.) Small European style back saws have teeth which are sort of
a hybrid between rip and crosscut. European style back
saws work well either crosscutting or ripping. If you are unsure of
your saw, try cutting a
scrap of hardwood along a line just
slightly off of the grain direction
and see how well it works.
Finally you can start on the pins. First you
need to mark them on the piece of wood you are working on. The
marking is done using the mating piece of wood as a
template. There are a lot of ways of doing
the marking. I will describe the approach I use,
which works well for me.
Clamp the piece of
wood which is getting the pins cut into it in the vise, pin edge up.
Raise the wood a small amount (1/16”) above the
bench surface. Lay the mating piece of wood on
top, aligning the reference edges. Try to put the bottoms of the
tails (end grain) just over the inside edge of the pin board (did you check to
make sure you know which is inside and which is outside?). You
can judge the edge location by using a knife blade as a sort of
feeler gauge. Alignment is very critical.
Now place a large weight on top of the tail
piece of wood. It is critical that neither piece of wood moves
during the marking. Check your alignment again.
Using a very sharp pencil or a
sharp knife, mark the pins using the holes in the tail
piece as a template. You must be careful to put
the mark at the very edge of the tail
holes, but you must also be
careful not to push the tail board and move it. A
knife works well here as you are marking in end grain,
but you must be careful not to shave off the bottom corners of the
tails!
Another thing which you must be very careful
about is how you mark the pins out on the opposite end of
the board you are working on. There
is only one right orientation for the two ends. You want to end up
with a box, not a zigzag of boards. Pay close attention
to which face is inside vs. outside and make the inside face the
same for both ends of the board.
Once you have marked all of the
pins, slide the tail piece of wood away from the pin
piece. Immediately mark both edges to indicate that these two and no
others go together, and also indicate which face is
inside and which face is outside. I often make cut marks with a narrow chisel
inside the pins and tails. You can easily make a line, a cross, a star, and a
hatch mark (1, 2, 3, 4 cuts). Put the marks where they
won’t show in the finished work, but not in the waste. While
the two boards are in close
proximity, cross out the waste portions of the pin
board. It is much easier to mark the waste correctly if the tails
are sitting right next door.
Now put the tail
board out of the way, and raise the pin board
high enough in the vise to mark the face and to saw. Using
a square, extend the lines you drew on the end grain down one face
to the scribe line. A pencil works best here since you are drawing with the
grain.
Now saw the
pins. Your saw must not cut inside the lines. Cut so that the saw kerf is entirely in the
waste. If you come inside the lines into the pin, you will have a
gap. How close you come to the line depends on how good you are at marking and
sawing. The closer you can come to the line (i.e. the more practice you
have), the quicker and easier dovetailing will be for
you.
As with the tails, saw starting on the end
grain to make a shallow groove, then angle the saw around to make a
groove part way down the face. Work the cut
down to just a saw kerf above the scribe lines on
both sides of the board. Once you have all of the cuts
down to the scribe lines, you
remove the waste with a chisel just like when you cut the
tails. Be careful of the fact that the pins are wider
on one face than the other.
5.
Fitting
Fitting is difficult at
first. Your goal is to shave away at the
places on the pins where there is too
much thickness, until they
exactly fit the holes between the tails. You should take
your time, making fine shavings with a sharp chisel, and frequently checking
the mating pieces against each other. If you prefer a file or rasp, by all
means use it. Shave the tails as a last resort, as I find shaving
the tails is a good way to make a mistake. The
more dovetails along a corner, the more difficult the fitting.
The ideal fit that
you strive for is one which you can assemble and
disassemble without using a mallet (just barely). It is terribly easy
to damage your wood surface with a mallet. The fit I
usually end up with needs light mallet work to assemble and
disassemble. If you experience any resistance to
assembly, try coating one side of the joint with chalk on
the rubbing surfaces. Partially assemble the joint, and
the chalk will mark the high spots you need to work on. You can also look for
shiny spots on the pins (compressed areas) to indicate high spots.
Some books will recommend a
tighter ideal fit, on the assumption that the pins and
tails will slightly crush each other on assembly and fit each other better as a
result. I have used this approach with good success in soft woods like pine and
cedar. I would not recommend using a this approach in hard woods, as it is too
easy to split something. Cherry in particular is a bit brittle and you must be
careful not to have too tight a fit.
6.
Gluing
Before you glue, take
time to think about how you are going to finish your
boards. You probably want to fine sand the inside pieces before
assembly, and you may want to finish the insides of the boards
before assembly, depending on how you are planning on finishing your
wood. I usually do not finish before assembly, but I
am less picky than a lot of people.
Before you glue, clear your bench
top. Place within easy reach a square, all of the clamps
you own, cardboard to pad the clamp jaws, towels, a
mallet and a scrap block of soft wood to shield your mallet blows. It is
probably a good idea to get someone to help you the first time you glue up a
box. I usually use yellow (aliphatic resin) wood
glue. If you have a complex assembly or
have not put many joints together before, use
white glue. White glue is not as strong as yellow
glue, but it takes longer to set up.
If you are making a
box, you must glue up all of the corners at
once to make sure everything is aligned. Apply
glue to all of the hidden surfaces of one joint on at least
one piece of wood. Some books recommend applying glue to both
pieces, but I worry about the extra time taken
allowing the glue to start setting up before assembly is
done. This can be pretty messy, and you must be careful
not to get glue where it doesn’t belong. Work
efficiently, and try not to panic. Assemble each joint
before applying glue to the next one.
If you
should still be assembling your
corners when the glue starts to set, please
don’t panic. Glue which is just starting to set is really not a
problem if you deal with it in the right manner. Do not
use your mallet to persuade a joint which is
setting. Glue which is beginning to set
responds best to steady pressure, not impulsive pounding.
After all of your corners have
been glued and assembled, check your corners for squareness. Put
pipe clamps around the outside of the joints to snug up any remaining gaps in
the dovetails. Watch where you put the clamp jaws as your
pins and tails should stand just a bit
proud of the surface. Adjust the tension on the clamps
gradually to square up the box. Your box will
probably not be perfectly square; reach a compromise
between the wood and your pride. Let the glue set overnight.
The next day remove all of the
clamps. The protruding ends of the
pins and tails can best be made flush with a
block plane. Now is also a good time to work carefully with a plane
to make the edges of adjacent pieces of wood meet exactly. Set your plane really
fine and be careful not to tear up the opposite piece.
Break all edges of
your assembly with a block plane or fine sand paper. You
will never see the difference, and your work will be much more
comfortable to hold. If you use a plane, be careful to work both
ends against the middle. Now is a really bad time to tear out part
of an edge.
Miscellaneous
Comments
When you are making a
box, you must decide
how to attach the bottom at the
beginning. One method is to cut a groove the same size as the bottom
thickness on the four sides of the box, so that the bottom is raised from the
lower edge of the sides. If you are making conventional through
dovetails, the groove must stop before it reaches the edge of the
board or it will show on the outside. Cutting a stopped groove is
difficult with hand tools. A better solution is to cut the groove all the way
to the edge of each board and put a mitered dovetail over it. Look at a picture
of this joint in a book to see how
it is done. It is not too hard, but
takes a little practice. The grooves should allow the
bottom some room side to side for expansion and contraction. Be sure that the
grooves on each of the four sides all line up with each other when you fit the
dovetails together!
Assembling
a box with a grooved bottom
is only a little bit trickier than
a dovetailed frame with no bottom. Assemble two of the
corners, then slide in the bottom and assemble the last
two corners. Do not glue your bottom in place.
Gluing this joint would result in cross grain construction. Leave the
bottom floating so it can expand and contract without stressing your joints.
A very elegant
addition to a box is a shaped footing. This is
really very easy to do if you use the right sequence. Cut a groove for the
bottom a couple of inches above the edge of the boards. After the
groove is finished, draw a pretty curve on the couple
of inches of each board below the bottom and saw out your
footing.
You can make the footing a separate frame
(from the main box frame). This short frame needs to be larger than the box,
and has a groove cut around the top edge just large enough for the box to drop
into. The two end up getting glued together. If you make the groove around the
top edge of the footing tall enough, you don’t need to stop the groove you cut
in the box to hold the bottom. Run the bottom groove all the way to the edge of
the board, and let the footing cover it.
There is another way to attach
the bottom with a separate footing piece. Assemble and glue the four
sides of your box. Cut a bottom board the same size as the outside edge of the
box. Make a small four sided frame (dovetailed, of course), larger than the
outside edge of the first box. This will turn into a footing. Cut curves in the
edges to decorate. Before you assemble the footing frame, cut a groove along
the top edge deep enough for both the bottom and the main box to drop in. The
bottom will be supported by the frame, and the box will sit on top of the
bottom. Both the bottom and a piece of the box need to drop into the groove. Remember
not to put glue on the bottom or you will end up with cross grain
construction. The frame needs to fit the box fairly well. You may want to cut
the groove with two steps, so that the bottom sits in one, and the box sits
above the bottom in the other step. This will help in keeping glue away from
the bottom.
A very nice way of
assembling the legs of a small table with a
central pillar is to install the legs with
sliding dovetails. These are pretty tricky to do right.
Fitting is much easier if you cut your dovetails at a steeper angle than
normal.
Guidgen
Craftsmanship can be defined in
a lot of ways. A fairly common usage includes the
statement do your
best work in all tasks”. Something that is often
misunderstood in this statement is the difference between
doing your best and perfectionism.
Doing your best means that you must reach
a compromise between your absolute best work (which takes a very long
time), and work which is of good quality but still allows you to get something
done. Almost everyone errs on the side of trying too hard to do
perfect work, and thus getting very little done. Perfectionism includes
the work which commonly graces the covers of magazines like Fine Woodworking.
Work like this is something to aspire to, and be inspired
by. It takes a huge amount of experience to do work of
Fine Woodworking caliber.
It is very important to include
the amount of work you get done in any estimate of how close you are to
“working at your best”. If you only do one piece each year,
your abilities will not improve very
much. Twenty shoddy pieces each year
will also not improve your
abilities much. Neither case is “working at
your best”. You must strike a balance, and
realize that medium quality work actually represents your best
work in the long run.
Do not be a slave to your
ruler. Measuring things as a specific
number of inches is a fairly modern concept, and
can take over a project unnecessarily. What usually
matters more than inches is
proportion. Sometimes there is
important dimensionality, but what counts is that
something fits, not that it is so many inches. I often
measure in hand spans. If you want
accuracy, you can mark the dimension carefully
on a piece of scrap. For proportion, a pair of
dividers works well to pace off the work. Rulers are
useful things, but please keep an open mind and avoid being
compulsive about them.
Power tools are very oversold. Also
oversold is sand paper. Both are extremely useful in
their place, but in a home workshop their place is limited.
Hand tools are generally faster,
have fewer health hazards and are much more pleasant to work with than power
tools. In order to know the truth of what I am saying, you must be willing
to work with a hand tool long enough to gain some proficiency
with it. Only after some mistakes and slow work will you begin to
see the efficiencies inherent in a given hand tool.
Power tools can speed up
repetitive work. Very little of what is done at home is
repetitive enough to justify the time spent setting up
a power tool and cleaning up the amazing
mess afterward. Also not
justified is the noise and dust, and
the sheer amount of space occupied
by power tools. I own many, and speak from experience. I only use a few.
There is another aspect of hand
tools which is really nice. Hand
tools give you the option of spending
money to acquire them, or spending
time to make them. Most any hand tool can be made for almost
no monetary expense. If you don’t believe
me, come to Unser Hafen Blacksmithing Guild
some time. We’ll make you some tools.
Some tasks are repetitive enough
that power tools make sense. Rip sawing (reducing the width of a long
board) is really a lot of work and not terribly entertaining. Rip
sawing is very sensibly done with power tools in these days of no
apprentices. Surface planing of rough lumber is also sensibly done with power
equipment.
Surface smoothing for finishing
is not a good use for sand paper. Most
surfaces are much better attacked with
a hand plane and a
scraper. To make a coarsely smoothed surface very smooth takes
a lot of time with sand paper (power or hand sanding). A plane and a
scraper do the job quite quickly. As a surface gets more curved, or
smaller, planes and scrapers make less sense and sandpaper makes more.
Introductory
Woodworking
If you sweep the floor clean
before you start, and throughout your work, it is much easier to find pieces of
wood which accidentally chip out that were not supposed
to be removed. The piece can easily be
glued back with either yellow wood glue or cyanoacrylate glue, with
none the wiser.
1.
Marking accurately and squarely
Making wooden joints often
involves careful marking of your piece of wood. If your marks are
not in the right place, you have no hope of sawing or chiseling accurately. You
rarely need to mark a specific distance on a board—rather,
you may need to mark an identical distance
(however long) on two boards. The tool used
for this task is a marking gauge. It consists of
a sharp point attached to a stick. The stick
is in turn held by a block of wood
(fence). The mark is made by putting the fence against
the edge of the board to be marked and scoring
the surface of the board with the
sharp point. The distance between the
fence and the sharp point is adjusted by a clamp which
holds the stick to the fence.
Another type of mark you need to
make is a mark perpendicular to one edge of a piece of
wood. To do this, you need an accurate square (you also
need a nice straight edge on the wood, discussed
later). You can buy a good square, or make a cheap one accurate by
adjusting it. A good test for a square (and also for your
marking ability) is to draw a line
around the entire circumference of a board
perhaps three or four inches square. Does
your line meet the starting place exactly?
How you make a mark can also affect
accuracy. A pencil line, even a fine one, has a lot more
error in its width than most wooden joints will tolerate. There are
two ways around this error. One is to use a knife edge to scribe a
very fine line, and then work carefully to this line. The other way
is to use a pencil line, and then fit two pieces to each
other (and promptly mark them unambiguously
as belonging to each other). Either way works
well, although if you use a pencil, it should be a fine one.
2.
Cutting to a line
First, start with sharp tools.
You cannot cut accurately (hand or power) with dull blades. See the appendix.
Whether you are cutting with hand or power
tools, watch the wood and the mark, not the
blade. Making an accurate cut requires practice and attention. A saw cut needs
to start straight. You cannot force the saw direction without ruining your
accuracy. Cutting straight is easy when you start straight.
You can avoid cutting
past your stop line if you realize that it is not
necessary to cut all the way to it. You only need
to cut to within one saw kerf of the stop
line. When all sawing is done, clean up the tiny bit
remaining in the corner with a chisel.
Starting a cut with a
hand saw is sometimes a bit tricky. At
first, the saw will sometimes jump and shudder
everywhere except at
your mark. This is typically caused by either using too
coarse of a
saw for the hardness of the
wood, using the wrong type of saw
(crosscut vs. rip) or putting pressure on the saw. Even after a cut is
started, you will get the most accurate cut if you
let gravity feed the saw. If you should end up
having started the cut slightly in the wrong place, instead of
trying to force the saw to your will, lay the
saw down almost flush with the
surface and gently broaden your starting cut
until you can saw in the correct place.
3.
Planing a straight edge
You can plane a much
better straight edge by hand than with a
power jointer or router. To do this, you need
the longest (sharp!) hand plane you can find. I use a No. 8 jointer
plane, which is about 24 inches long. You must have some
arrangement for holding the board to be planed without requiring any
attention from you. Your cuts will not be true
if you have to hold the board with your elbow and knee
while you plane. At the start of a cut, push down on the front of
the plane only. At the end of the cut, push down on the back of the
plane only (at the handle). Think
of your action as trying to plane a concave
edge, and you will end up with a straight
edge. Eyeball the edge when you are done—it should be
absolutely straight after only a little practice.
If it is important to
have the edge exactly at 90 degrees to the face, lay the
board on it’s face, spaced about 1/8” above the
bench. Now lay the plane on it’s side, and plane the edge. If you do
a lot of this, you should build a fixture for
it so that you don’t wear a groove in your
workbench.
4.
Gluing up boards
Spend a lot of time before you
apply glue arranging your boards so that matching edges end
up next to each other. Mark adjacent edges
(and front/back) so you can find the arrangement again. If you
choose and arrange your boards carefully, most people will not
realize that your nice wide board is glued up from smaller ones.
To glue two edges together with no gaps, the
edges both need to be absolutely straight, and at complimentary
angles to each other. The edges do not need to be at 90
degrees to their faces. To joint two boards to
match, lay the boards next to each other on the bench in the
preferred final orientation. Now pick them up, and fold
them as if there is a hinge joining them. Clamp them in your vise
this way; back to back or front to front. Now joint the edge. If
your planing results in a nice straight edge which is a
bit off of 90 degrees, you will still have a
flat panel when gluing is done since the errors in the
two boards will cancel each other.
If you are forced to close gaps between
boards with a lot of clamp pressure, something is wrong. If you have done your
edging right, you should be able to apply glue to the
edges, push and wring the edges together and get them to
stick to each other with no clamps, just the surface tension of the
glue. Try it some time, it is a lot of fun.
Don’t use an
excessive amount of glue. Some
books and articles will admonish you to “get
the right amount of squeeze out” when you
clamp. The right amount of squeeze out is none. You do
need to make sure glue coats the entire edge (both pieces!), so in
practice you get some squeeze out. The ideal would be to have glue
just come up to the edge and no farther. When you apply
glue, make sure it covers each edge completely, in as
even and thin a layer as you can.
I usually space my clamps between one and
two feet apart for edge gluing ¾” thick stock. It is nice
to have more clamps than you think you need in case a problem comes up when you
are clamping. Alternate the clamps top and
bottom to keep the surface flat. With one inch and
thicker stock, you can get away with a lot in terms of
clamp spacing and uneven pressure between
clamps if your edges mate nicely. When edge gluing
½” and smaller, you must be very careful to
get even clamping pressure. Tighten the clamps little by
little, so that they all reach final pressure together. As you
tighten, check the face for flatness, to make sure you are not
introducing a cup into the panel.
Take great care in making the
faces of your boards all lie in the same plane. This
can save you a tremendous amount of work later. If you tighten your
clamps little by little, it is much easier to adjust the edges. If
you adjust the edges with the clamps too tight, you will introduce a bend in
the board. If you have a hard time with this, or have a
panel which must end up with a really flush surface, invest in a
doweling jig, and put dowels in to align the edges.
5.
Planing end grain
A block plane is specially
designed to be able to plane end grain. If your plane is very
sharp, and you take a nice thin cut, end grain
is fairly easy to plane. Be careful at the far
end of the board, however, as it is
easy to tear a huge chunk off of the edge. You can either plane both
ends against the middle, or else clamp the board to be planed firmly
up next to a piece of scrap to support the
far edge. Sanded end grain looks nothing like planed end
grain.
6.
Avoiding cross grain construction
When two pieces of
wood are attached rigidly to each other, and the grain
on one piece is perpendicular to the grain on the other, a
split will inevitably develop with time. Wood
expands a lot more perpendicular to the grain
than parallel to the grain.
A lot of period chests are made with cross
grain construction, and have the splits to prove it. A lot of known world
workmanship also has cross grain construction, and will either split or come
apart at the cross grain joints in
time. A common chest design in the current
middle ages has grain running horizontally front and back, with
grain running vertically on the end pieces (which extend below the bottom of
the chest as legs).
There are
three reasons for building
chests with cross grain
construction—ignorance, “its period”, and
expediency. I feel that only the first reason is valid.
The second reason is not valid—there are many period examples of
chests with no cross grain construction, including
properly constructed cases and also frame and panel. The
third reason is quite questionable in
my mind. If you are not
interested in your work lasting, then you must have
quite different motives from my own.
7.
Sharpening
If you want to risk your tools,
you can try using a high speed motorized grinder. Several
things can improve the risk:
·
slow the grinder down to 1725 rpm
·
get “cool” type grinding wheels
·
back the blade you are
sharpening with a larger piece of
metal (a heat sink). Before grinding, dip the
assembly in water. The water wicks up between
the two pieces of metal ensuring good thermal contact.
A much better choice is a hand
powered grinder—not because of any hand tool mystique, but because
it is extremely difficult to overheat your tools with a hand grinder.
Either of the above methods should give you
a hollow ground edge.
Use either a small square or a sharpening
jig to check your edge accuracy
Before you can sharpen the edge
you rough shaped, you must polish the back of the blade. You need to
gradually move to finer and finer abrasives in the polishing process. I follow
any rough grinding with a fine Carborundum stone (“India”
stone), followed by a Washita stone. If the tool
is a particularly nice one I end up on a “Soft Arkansas” stone. There
are at least two finer grades than “Soft
Arkansas”, but I have
not found them to noticeably improve matters
in general woodworking.
The back should be very flat and shiny when
you are done. Only when the back is polished does it make sense to
fine sharpen the edge of the blade. You only need to get
the tip of the hollow ground edge sharp. Now you can proceed to sharpen the
hollow ground side.
When you sharpen a blade, hold
it very near the edge, and move the blade in small circles. You will have much
better control of the blade angle.
8.
Sanding
A lot of the
time, sanding makes some sense. Surfaces which have
grain pointing different directions (such as curves) can
be insanely difficult to work with edged tools. Flat surfaces are very efficient to smooth
with a plane after you have some practice in its use. If
you have never used a plane, get a small block
plane, read about how to use it and use it for a bit on
every project you make. Using a plane without any experience
and not using sandpaper at all will slow you down a
lot. Get some woodworking done while you gain planing experience
gradually.
Sanding
is most effective if you
start with a coarse enough
abrasive. Your abrasive must be almost as coarse as the irregularities in the
surface. Typically, start with 80 grit paper (60 grit
if you are trying to remove a bunch of
wood). 80 grit paper is good for
removing typical power tool marks, like a machine planed
surface. If you want your surface to stay flat, wrap the sand paper
around a flat block rather than holding the paper in your hand. Sand
all areas which need it with #80 before changing grit size.
The largest jump in grit size
you should make is about 1.5 times as fine. If you
started with #80, your next choice should be no finer than
#120, followed with no finer than #180, etc. If you take
larger steps, it will make your sanding take a lot longer. At each
grade you use, be sure to sand all of the areas you
sanded with the previous grit. Work in high
contrast lighting, like direct sunlight, so that
you can see the scratches in your work from the
previous grit. Take them all out before going to a finer
grade. If scratches show up after
you start on a new grit and don’t
sand out quickly, you should consider going
back to a bit coarser grit for a while.
For
everyday projects, you can stop at #150 or
#220. There is little point in
using any finer grits on items
you plan on taking camping with you. For
surfaces you want smoother that are made of harder woods,
it can make sense to go all the way up to #600.
9.
Finishing
I don’t know a lot
about finishing, so I use a couple of easy
methods, oil finish and varnish.
Oil finish brings out a lot of
inherent color in the wood, and is available in ‘natural’ and
various stains. A couple of good brands are Watco and Deft. Read the
directions! I do not recommend linseed oil or dried linseed oil, as they take a
lot longer to dry.
Oil finishes can be enhanced by
applying a wax after they are quite dry. You need a
wax intended for the purpose that is compatible
with an oil finish. Watco makes a wax specially made
to work with their oil. I haven’t done much of this, but
it can be very pretty.
Varnish
provides much more protection
to the wood than oil.
Varnish soaks into the wood and
hardens, making the wood surface much more tolerant
of abuse. Most varnishes also provide much more
protection against water than an oil finish. If your wood will spend a lot of
time in sunlight, get a polyurethane varnish for outdoor use.
The
difficulty in using varnish
lies in not getting little
hardened drips of varnish at the bottom edge of
your piece. Varnish also takes the patience to
apply several coats. I use Last and Last
brand primarily because we have some left over from when
we did our wood floors. Read the directions!
It is
very important to read the directions on
finishes. Especially Important is the fire danger which finish saturated rags
or paper towels represent. As the finish dries, a small amount of heat is
generated. If the heat is confined, like in a wadded up
towel in the trash can, the material can
spontaneously combust hours later. I throw my
finish rags in the wood stove. I prefer
a satin finish to a gloss finish. Try both, and see what you like.
Cutting
dovetails
Dovetail joints are really fine
things. They are both esthetically pleasing and amazingly strong at
the same time. Mortise and tenon joints are
strong, not much easier than dovetails, and when
you are done, no one can see all of your work! Dovetail joints have a bit of terminology
associated with them. One side of the joint is
called the tail, because the fan shape is
reminiscent of a spread dove’s tail. The other side of
the joint is called the pin (why I
have no idea). Be careful as some authors
reverse this.
1.
Stock preparation
Leave your stock long while you prepare
one edge. Taking all of
the pieces out of one board is a smart
idea, as they will match better. Make
one edge of your board absolutely straight with a long
plane. This edge will end up as the reference
edge from which all measurements and
alignments are made. Leave the other edge rough so that the
difference is obvious.
Using an accurate square, draw lines perpendicular to your
reference edge to mark out the lengths of wood
you will be using. Remember that your
saw cut has width, and keep the saw in the same place in
relation to your line. Either cut on one side of the line, or down the middle
of the line, but do the same thing the entire length of the board.
Do not cut your stock to final size. Allow
yourself some room. The pins and tails of your joints (on each end of the
board) should be perhaps 1/32” extra long, so that when
the joint is assembled a bit extra sticks
out. This allows you to end up with
a flush surface (by planing away the excess), rather than a sunken
one. You should also expect to do some finish planing on the other
edges, those not involved in a joint.
The edges
of your boards should be
cut square and even. Any wavering
in the edge, especially in the end grain, must be allowed for
when you mark your stock so that you don’t end
up with a recessed
tail. If the end grain is not square
to the edge you may have such misalignment
that it will be impossible to assemble all
four corners at once.
Check
your pieces after you cut them with a square
and straightedge. If the end grain is not square to the reference edge, or if
your cut wavers, it is usually a lot easier to plane the end smooth and square
now. You should also compare sizes on pieces which need to match
each other. I often plane two pieces at once in the vise so that they are
exactly the same size. If they are not the same size, your box will be
trapezoidal instead of rectangular.
Mark the orientation of your
boards if it is important (mainly for appearance). You will have a
hard time figuring it out later.
2.
Marking
Set your marking
gauge just a bit more than the thickness of the
boards you are using (1/32” or so). Lightly
score the boards to be
dovetailed together, along the edges to be
joined. I usually score
face, back, and edges for each board
in each joint. These marks indicate the
edges of the pins and tails. The marks also show where the inside edge of the
board forming the other half of the joint lies. If your marks do not
end up straight lines, your finished assembly will show gaps along this edge.
3.
Cutting tails
You must have very good lighting
to cut dovetails. You must have light down on your bench
for marking and measuring. You must also have light from the side (or below) so
that you can see while sawing. Get a lamp which you can place where you need it
and you will save lots of frustration and squinting.
There are a lot of
sequences which work in cutting dovetails. I like to cut
the tails first, but it also works to cut the pins first. Begin by deciding how many dovetails you are
going to put in an edge, where they will go, and how big
they should be. Some of the considerations follow:
If you space your dovetails
unevenly (as I almost always do), put them near the high stress
points. In a box, the stress is mostly along the top and bottom, especially the
top edge.
Evenly spaced
dovetails, especially with pins and tails the same size,
is what you get out of a dovetail template. Why try to imitate a
router? This is kind of a modern argument, one that
didn’t occur to people in the middle ages.
At the edges of your joint, there will
typically be either half of a tail or pin. Half of a pin is stronger than half
of a tail, and a better choice.
I usually mark the centers of
the tails first, once I have decided on a layout. In marking the
tails, please note that accuracy is not critical. The
pins will be sized to fit the tails by marking them from the finished tails.
Whatever angles, size and spacing your tails end up with, your pins will be cut
to match.
If your tails have identical
spacing on two or more corners, it is a lot easier to mark the locations on a
piece of scrap and transfer the marks from the scrap to both corners. This
greatly reduces mistakes and speeds up the work.
Use a pencil to mark the
tails. With ring-porous woods like oak,
it is easy for a knife mark to get lost in the
grain. Also it is
difficult to draw a straight line not quite in line
with the grain using a knife blade. The grain pulls the
knife off of the line you are trying to draw.
Draw the tails using
a bevel gauge. I set mine to an angle of about
1:6 (1 over and 6 up). People seem to use a variety of
angles, including 1:8 and 80 degrees. Draw the tails between the
scribed line and the end of the board. Now go along the edge and X
out all of the pieces which are to be removed (in pencil). Look
carefully at what you have
drawn. Did you really cross out the scrap, not
the good parts? Are you tails drawn right, or are they reversed? Look
carefully, this is easy to mess up!
Using a small square, extend
the lines you have drawn straight down the end grain
across the thickness of the board, marking each side of the tail.
Put the piece of wood in a
vise, edge up. Start sawing along the mark in
the end grain until you have a shallow groove. Now rotate
the saw so it is pointing straight up and down and make a shallow groove along
the face of the board. Now angle the saw more and more, joining the
two saw marks you have made along the diagonal.
Be careful not to cut beyond the scribed line
on the face of the board. By working
back and forth along these grooves, you can guarantee
that the cut
will be in the right place when it comes out
the far side of the
board. This is a good thing to practice a lot
on scraps of wood, either making square or
angled cutoffs. Remember not to force the saw.
Saw
carefully along the pencil
lines, on whichever side you
choose, not quite up to the scribe line. Once the cut is
deep enough that the saw is self guiding, bring the saw
horizontal and saw down
almost to the scribe line. Check both sides of
the board as you approach the
scribe line so that you don’t unknowingly saw past the
line on one side of the board.
Since you are going to use the tails to mark
the lines for cutting the pins, the
size of each tail is not critical. This is, however, an
excellent chance to practice your sawing to a line. Now you
need to remove the waste from between your saw cuts.
Before you start, once again
examine your X’s marking the waste pieces to be removed. Are you sure they are
in the right place? You can use either a fine turning saw or a chisel for
rough stock removal. I use a mortising chisel.
The type
of chisel you use
for rough stock removal is not
critical, as long as it is narrow enough so
it doesn’t score the inside edges
of the tails. Your chisel must also be tough enough to
deal with rough stock removal. Many bevel edge chisels
will chip if you use them for chopping.
Each time you start work in a
new spot, ask yourself if that spot is really waste
material. Every time you pick up the
board you are chiseling on, you must clean the
area underneath it. A small chunk of wood can make a nasty dent in the surface.
First remove most, but not all of the waste.
Leave a bit of waste, maybe 1/16” in front of the scribe
line. Chisel down onto a piece of scrap on your workbench so that
you don’t cut into your bench. Chop down, and then chip out the part you have
cut through (from the end grain). Proceed like this at least halfway
through the wood, and then turn
the board over and finish the cut from the
other side.
Now move your chisel
to the scribed line. For this cut you might want to
sharpen your mortise chisel or use a bevel chisel. Tap the chisel
gently with a mallet to set it in
the line, and then tap a bit harder
until you are about halfway
through. Do the same thing from the other
side and you are done removing the
waste.
Your chisel needs to be either exactly
perpendicular to the board, or at an angle which will give you more clearance
in the middle of the cut, not less clearance. When the joint is
assembled, you will not be able to tell if you have undercut the
middle part of the tail. Waste left in the middle results in
unsightly gaps after assembly.
Take the time now to trim up the
sawn edges of your tails with a chisel. The edges don’t
need to be perfectly smooth, but they should be pretty straight. A
fine saw or a knife can also be useful. If any of your tails ended up with wavering
edges, straighten them up now.
4.
Cutting pins
When you cut the
tails, you were cutting at an angle to the grain in the wood.
Cutting the pins is directly along the grain. This can be a
problem, especially if you are using one of the very
fine Japanese pull saws. To see why, you need
to understand the difference between rip saws and crosscut saws.
When you are cutting across the
grain, the smoothest cut will be had with a saw whose
teeth are shaped like tiny knives. This type of saw will cleanly
sever the wood
fibers. Crosscut saws have teeth
shaped like knives.
When you are cutting with the
grain, a different shaped tooth is needed.
. If your saw teeth are knife shaped (crosscut), the saw
is going to follow the wood fibers. To allow the saw to be
guided, a chisel shaped tooth works best. Saws with
chisel shaped teeth are called rip saws. When you cut the pins, you are cutting
in the same general direction as the grain, but probably not exactly the same.
Japanese back
saws have teeth which are extremely knife shaped. This
makes them very difficult to guide in cutting pins. (There
is a type of Japanese saw intended for ripping, but it is not very
common.) Small European style back saws have teeth which are sort of
a hybrid between rip and crosscut. European style back
saws work well either crosscutting or ripping. If you are unsure of
your saw, try cutting a
scrap of hardwood along a line just
slightly off of the grain direction
and see how well it works.
Finally you can start on the pins. First you
need to mark them on the piece of wood you are working on. The
marking is done using the mating piece of wood as a
template. There are a lot of ways of doing
the marking. I will describe the approach I use,
which works well for me.
Clamp the piece of
wood which is getting the pins cut into it in the vise, pin edge up.
Raise the wood a small amount (1/16”) above the
bench surface. Lay the mating piece of wood on
top, aligning the reference edges. Try to put the bottoms of the
tails (end grain) just over the inside edge of the pin board (did you check to
make sure you know which is inside and which is outside?). You
can judge the edge location by using a knife blade as a sort of
feeler gauge. Alignment is very critical.
Now place a large weight on top of the tail
piece of wood. It is critical that neither piece of wood moves
during the marking. Check your alignment again.
Using a very sharp pencil or a
sharp knife, mark the pins using the holes in the tail
piece as a template. You must be careful to put
the mark at the very edge of the tail
holes, but you must also be
careful not to push the tail board and move it. A
knife works well here as you are marking in end grain,
but you must be careful not to shave off the bottom corners of the
tails!
Another thing which you must be very careful
about is how you mark the pins out on the opposite end of
the board you are working on. There
is only one right orientation for the two ends. You want to end up
with a box, not a zigzag of boards. Pay close attention
to which face is inside vs. outside and make the inside face the
same for both ends of the board.
Once you have marked all of the
pins, slide the tail piece of wood away from the pin
piece. Immediately mark both edges to indicate that these two and no
others go together, and also indicate which face is
inside and which face is outside. I often make cut marks with a narrow chisel
inside the pins and tails. You can easily make a line, a cross, a star, and a
hatch mark (1, 2, 3, 4 cuts). Put the marks where they
won’t show in the finished work, but not in the waste. While
the two boards are in close
proximity, cross out the waste portions of the pin
board. It is much easier to mark the waste correctly if the tails
are sitting right next door.
Now put the tail
board out of the way, and raise the pin board
high enough in the vise to mark the face and to saw. Using
a square, extend the lines you drew on the end grain down one face
to the scribe line. A pencil works best here since you are drawing with the
grain.
Now saw the
pins. Your saw must not cut inside the lines. Cut so that the saw kerf is entirely in the
waste. If you come inside the lines into the pin, you will have a
gap. How close you come to the line depends on how good you are at marking and
sawing. The closer you can come to the line (i.e. the more practice you
have), the quicker and easier dovetailing will be for
you.
As with the tails, saw starting on the end
grain to make a shallow groove, then angle the saw around to make a
groove part way down the face. Work the cut
down to just a saw kerf above the scribe lines on
both sides of the board. Once you have all of the cuts
down to the scribe lines, you
remove the waste with a chisel just like when you cut the
tails. Be careful of the fact that the pins are wider
on one face than the other.
5.
Fitting
Fitting is difficult at
first. Your goal is to shave away at the
places on the pins where there is too
much thickness, until they
exactly fit the holes between the tails. You should take
your time, making fine shavings with a sharp chisel, and frequently checking
the mating pieces against each other. If you prefer a file or rasp, by all
means use it. Shave the tails as a last resort, as I find shaving
the tails is a good way to make a mistake. The
more dovetails along a corner, the more difficult the fitting.
The ideal fit that
you strive for is one which you can assemble and
disassemble without using a mallet (just barely). It is terribly easy
to damage your wood surface with a mallet. The fit I
usually end up with needs light mallet work to assemble and
disassemble. If you experience any resistance to
assembly, try coating one side of the joint with chalk on
the rubbing surfaces. Partially assemble the joint, and
the chalk will mark the high spots you need to work on. You can also look for
shiny spots on the pins (compressed areas) to indicate high spots.
Some books will recommend a
tighter ideal fit, on the assumption that the pins and
tails will slightly crush each other on assembly and fit each other better as a
result. I have used this approach with good success in soft woods like pine and
cedar. I would not recommend using a this approach in hard woods, as it is too
easy to split something. Cherry in particular is a bit brittle and you must be
careful not to have too tight a fit.
6.
Gluing
Before you glue, take
time to think about how you are going to finish your
boards. You probably want to fine sand the inside pieces before
assembly, and you may want to finish the insides of the boards
before assembly, depending on how you are planning on finishing your
wood. I usually do not finish before assembly, but I
am less picky than a lot of people.
Before you glue, clear your bench
top. Place within easy reach a square, all of the clamps
you own, cardboard to pad the clamp jaws, towels, a
mallet and a scrap block of soft wood to shield your mallet blows. It is
probably a good idea to get someone to help you the first time you glue up a
box. I usually use yellow (aliphatic resin) wood
glue. If you have a complex assembly or
have not put many joints together before, use
white glue. White glue is not as strong as yellow
glue, but it takes longer to set up.
If you are making a
box, you must glue up all of the corners at
once to make sure everything is aligned. Apply
glue to all of the hidden surfaces of one joint on at least
one piece of wood. Some books recommend applying glue to both
pieces, but I worry about the extra time taken
allowing the glue to start setting up before assembly is
done. This can be pretty messy, and you must be careful
not to get glue where it doesn’t belong. Work
efficiently, and try not to panic. Assemble each joint
before applying glue to the next one.
If you
should still be assembling your
corners when the glue starts to set, please
don’t panic. Glue which is just starting to set is really not a
problem if you deal with it in the right manner. Do not
use your mallet to persuade a joint which is
setting. Glue which is beginning to set
responds best to steady pressure, not impulsive pounding.
After all of your corners have
been glued and assembled, check your corners for squareness. Put
pipe clamps around the outside of the joints to snug up any remaining gaps in
the dovetails. Watch where you put the clamp jaws as your
pins and tails should stand just a bit
proud of the surface. Adjust the tension on the clamps
gradually to square up the box. Your box will
probably not be perfectly square; reach a compromise
between the wood and your pride. Let the glue set overnight.
The next day remove all of the
clamps. The protruding ends of the
pins and tails can best be made flush with a
block plane. Now is also a good time to work carefully with a plane
to make the edges of adjacent pieces of wood meet exactly. Set your plane really
fine and be careful not to tear up the opposite piece.
Break all edges of
your assembly with a block plane or fine sand paper. You
will never see the difference, and your work will be much more
comfortable to hold. If you use a plane, be careful to work both
ends against the middle. Now is a really bad time to tear out part
of an edge.
Miscellaneous
Comments
When you are making a
box, you must decide
how to attach the bottom at the
beginning. One method is to cut a groove the same size as the bottom
thickness on the four sides of the box, so that the bottom is raised from the
lower edge of the sides. If you are making conventional through
dovetails, the groove must stop before it reaches the edge of the
board or it will show on the outside. Cutting a stopped groove is
difficult with hand tools. A better solution is to cut the groove all the way
to the edge of each board and put a mitered dovetail over it. Look at a picture
of this joint in a book to see how
it is done. It is not too hard, but
takes a little practice. The grooves should allow the
bottom some room side to side for expansion and contraction. Be sure that the
grooves on each of the four sides all line up with each other when you fit the
dovetails together!
Assembling
a box with a grooved bottom
is only a little bit trickier than
a dovetailed frame with no bottom. Assemble two of the
corners, then slide in the bottom and assemble the last
two corners. Do not glue your bottom in place.
Gluing this joint would result in cross grain construction. Leave the
bottom floating so it can expand and contract without stressing your joints.
A very elegant
addition to a box is a shaped footing. This is
really very easy to do if you use the right sequence. Cut a groove for the
bottom a couple of inches above the edge of the boards. After the
groove is finished, draw a pretty curve on the couple
of inches of each board below the bottom and saw out your
footing.
You can make the footing a separate frame
(from the main box frame). This short frame needs to be larger than the box,
and has a groove cut around the top edge just large enough for the box to drop
into. The two end up getting glued together. If you make the groove around the
top edge of the footing tall enough, you don’t need to stop the groove you cut
in the box to hold the bottom. Run the bottom groove all the way to the edge of
the board, and let the footing cover it.
There is another way to attach
the bottom with a separate footing piece. Assemble and glue the four
sides of your box. Cut a bottom board the same size as the outside edge of the
box. Make a small four sided frame (dovetailed, of course), larger than the
outside edge of the first box. This will turn into a footing. Cut curves in the
edges to decorate. Before you assemble the footing frame, cut a groove along
the top edge deep enough for both the bottom and the main box to drop in. The
bottom will be supported by the frame, and the box will sit on top of the
bottom. Both the bottom and a piece of the box need to drop into the groove. Remember
not to put glue on the bottom or you will end up with cross grain
construction. The frame needs to fit the box fairly well. You may want to cut
the groove with two steps, so that the bottom sits in one, and the box sits
above the bottom in the other step. This will help in keeping glue away from
the bottom.
A very nice way of
assembling the legs of a small table with a
central pillar is to install the legs with
sliding dovetails. These are pretty tricky to do right.
Fitting is much easier if you cut your dovetails at a steeper angle than
normal.