Band clamps, spring wire pinch "clamps" and tape
are all great ideas. BTW, they make spring wire
pinch "clamps" that don't require the special "pliers".
As is often the case, I failed to provide critical info.
I tend to evolve pieces, making part one, dry fitting or glueing
it up, then figure out, based on what I've got, what to do next.
And being an impatient person, I often put a finish on what I
have so far in order to see what will go with it.
Unlike the more organized segment of the population, the
ones who make a cut list and actually remember to take it
with them to the lumber supplier, I often just rummage
through what I've got looking for something that's thick
enough, long enough and wide enough to work - AND might
go with what I've got. In this case, it was some walnut,
resawn a year or so ago from some tree branches. What
I had was maybe 3/8" thick and perhaps 18" long. Not
of a size that lends itself to proper stock prep - with a
joiner and planer. A drum sander got two faces smooth
and parallel but the parts weren't flat. I did join one
edge using a #6, with a Hock iron and chip breaker
just to gloat a little, and ripped a parallel edge.
Now if you've tried to make a picture frame out of
bowed, slightyl cupped or twisted parts you're
familiar with the phrase "an exercise in futility".
But, if you've already made the box this "frame" is
going on, you have more glue surfaces than just at the
mitered corners to help you compensate for less than
perfectly prepared stock. If you add a rabbet the glue
surface increases even more.
So I'm using the top of the existing box to act as an
inside jig. It holds the vertical alignment and, once
the mitered corners are tight and fixed in place,
with clamps, slight twists, bows or cupping can be
pulled in and straightened out. Once the glue's
set the parts will stay put. But, with all the necessary
clamps in place. getting to squeeze out is tough if
Band clamps cover the outside of the mitered corners
so you can't see them and pull in twists or cupping.
They'll let you clamp in the sides but there's still
the covered corners.
Spring pinch clamps let you see the outside corners
of the mitered corners but can open up as you pull
the sides into the case. If the spring pinch clamps
are strong enough to hold they're apt to split the
Still looks like a pin nailer is probably the best
solution for this particular situation. Unless
someone's got a better idea . . .