On 5 Aug 2004 17:54:45 -0700, (Joe McGuckin) wrote:

I'd like to build a wooden case to keep them in.

My instrument cases all follow much the same design. Two cases, nested
inside the each other. The inner case has all the complex pockets
etc., and is generally held together with half-laps or mortice &
tenons. Wrapped around this is an outer box that's a "hard shell".

For the outer carcase I'd use a tropical, like African mahogany. It
has the advantage of stability. My favoured wood source for this is
old 1950s wardrobe doors, because they're big wide single panels that
are already well dried and extremely stable. I can buy modern timber,
but not in the same widths without paying a lot for it.

Inside I use lime (basswood), because of its moisture properties. I
may use this for the outer carcase too, if I'm going for traditional
Japanese work (I can't source Paulownia).

Finger joints are the best joinery. Dovetails are for those who either
_want_ to cut them, or know they can cut this many and do them all
accurately. Much of the strength actually comes from the two-layer
internal construction and staggering the joint lines.

I wouldn't seal the case and make it waterproof. If I need that, then
I buy in a ready-made plastic case. A small mating rebate around the
lid edges is worth the trouble though.

Tops and bottoms can either be nailed on, or set slightly loose in an
internal groove. They're not a structural part, they're an ablative
buffer in case of serious impact. The strength is supplied by the
internal lime framework. Have the panels spaced slightly away from the
inner frame.

To get internal "spring" on a lid clamp, I like to make a tiny wooden
replica of a "sprung" dancefloor. Lime works well for this - Fretsaw
the closure frame inside the lid so that the pressure pad is supported
by a 2" long cantilevered long-grain beam, fastened only at the ends.
Unlike felt padding, this won't compress with age. For something
complicated like a theodolite, make the lid part of the internal frame
and hinge it to the lower inside part, so that it closes separately
and before the main lid.

Label the internal nests so that it's clear where things go, how they
go in, and which way you need to point their hinged brackets etc. to
fit. Take a photograph or diagram of it correctly loaded and glue it
inside the lid if you need to. Remember, it's not always you who will
be loading it.

Don't use felt for padding. It has obvious problems with moisture, but
it also gives off sulphur and that can be a problem for brass or
disaster for silver. Use closed-cell polyethylene foam instead - tool
box liners.

Design in space for dehumidifiers, ideally a removable sack the size
of a sock. The little teabag sachets are too small to be of any use.
Provide an obvious designated place for it, and a little brass strip
or sprung wire clamp to hold it there.

Shellac is a good finish. Give it a week of warmth and there's no
outgassing problems.

Study Victorian military campaign furniture for the best ideas about
hinge, locks, handles and corner guards. Finding this sort of quality
brassware isn't too hard these days, although some of it gets
expensive.


A cheaper option is to go to a big mil-surplus dealer. Top quality
fibreglass cases come in every size and for minimal money.

I wouldn't use a Haliburton product because they're evil *******s.

--
Smert' spamionam