On Sun, 28 Nov 2004 15:46:34 -0000, "Sam Berlyn"
That's because you've not made one before. I have made them, which is
why I hate making them. Mitres are a pain. They rely on a finicky
measurement you have to get perfectly right before you assemble it,
and they're a _real_
pain to clamp up while they're gluing.
Don't do mitres - they're horrible!
Assuming you're going to do them anyway, then a lot depends on which
way round they're going. How big is your box ? A "long tube", or a
"short tray" ? The difference is that the first is long mitres on
short timber, usually "long grain" surfaces. The second is short
mitres on long bits of wood and probably "end grain" surfaces.
I'd suggest you begin by making a picture frame. This is a classic
case where mitres are appropriate and commonplace. Obviously these are
the "end grain" sort. Buy your picture frame moulding (Hobby World)
and cut a rectangle of glass, or even have it cut to size at the
glazier (or even buy a glazed frame from Ikea / Poundsaver and throw
away the frame - often the cheapest way to get one-offs of glass).
Picture frames are nice and easy because you have the glass or backing
board to clamp the frame onto. If you don't, cut a backing board from
hardboard - it's easier to do this than it is to clamp the mitre up
Saw your frame as accurately as you can. This means your favourite
mitre saw and an accurate mitre box (wood is better than plastic).
Don't buy a "mitre saw". Unless you get a good one (e.g. Nobex) then
the saw blades are rubbish and they cut badly. Do your best to keep
the lengths matching too - it's better to make pairs that match
exactly, rather than pairs that are near the length you intended.
Now choose your glue. You want something with good initial "tack", not
something that takes ages. Titebond is better than plain PVA or Resin
Finally you need a clamping tool. One of the best is easily home made.
Make four "corners"; a 3/4 circle of MDF or ply, with a square
internal corner. File a groove into the outer edge. Now take a loop
of string the right size and a stick like a pencil. Place them round
the frame, loop the string round the grooves, then use the stick as a
"Spanish windlass" to twist the string tight. Use a square to judge
the squareness of each corner - this is where the flat workbench top
covered with plastic sheet (big carrier bag taped down) and the
backing board as an internal scaffolding come in handy.
With a little experience of mitres and the vagaries (mainly their
tendency to fall to pieces when you try to glue and clamp them),
you'll begin to understand why I dislike them.
When your frame is finished and the glue dried, take a look at it.
Because you assembled it wet, all four corners should be glued, but
any inaccuracy will be distributed around them. There will be a little
bit of gaping somewhere. The better you saw it, the less this will
be. If you make the frame the other way; using a magic clamp to
assemble each joint one-by-one, then you'll have three perfect joints
and one that doesn't even meet ! On the whole the "all together"
clmaping works better.
For a "tube" box, your clamping is easier (less tendency to squash
inwards) but it's harder to saw it accurately. It still needs a plug
in the base to give the clamps something to press down onto.
To saw long mitre joints, it's a good time to use a table saw with
either a tilting blade or a sled (a sliding wedge that carries the
timber at an angle). This is still awkward though, especially with
small pieces. If you cut them by hand, then look at a mitre box
called a "board mitre" (pics on the web). It's also a good idea to
plane the mitres after sawing them, using a "shooting board" or
"donkey's ear" to hold the plane at the right angle. Robert Wearing's
book "Woodworking Aids and Devices" also describes a router gadget to
hold timber for machining to the right angle.
For making mitred boxes, especially those awkward compound mitred
boxes, then a good tool for clamping them is parcel-wrapping cling
film (saran wrap), as sold by stationers rather than kitchen shops, on
a roller handle.
If you have the machinery to cut it (which means a table saw), then I
prefer to cut a splined mitre. This begins as a plain mitre, but then
has a groove cut into the joint edges and a key of thin wood inserted.
Because this holds it in place, it's much easier to clamp up.
On the whole though, I'd suggest a rebated half-lap rather than a long
I was reading James Ayres' "British Domestic Interiors" this weekend,
and he has some very scathing comments to make on mitres, and their
inappropriateness for good joinery.