Go Bars

[Ron Nossaman]

>Ron,
>
>If anyone can have success with this technique, I'm sure it is you,
>however, I worry about any glued wood joint that has not been clamped. 
>Of course, as  you imply, proper fitting is crucial (we also use the
>Spurlock/Bolduc method, Terry) but we also wedge the board up  
>>>>slightly<<< which temporarily induces some extra crown during the
>shimming process.  This additional radius makes it rather difficult to
>encourage the shim to stay put without some clamping.
-------------------------------
>
>Stan Kroeker

Hi Stan,
Long ago, but not that far away, I got frustrated by trying to keep supply
house shims in the joint and there must be a way to do it that was klutz
resistant enough that I didn't have to fight it. I played around with some
scrap wood and made/modified scrapers until I determined that a dry 14°
shim tapped into a crack shaped to the same angle (or very slightly less)
as the shim will wedge in good enough that it's very difficult to pull it
out. With glue, tapped in with a small hammer and backing block, it's a
death grip after a couple of seconds, and you'd better have the shim where
you want it because it isn't going to move without destroying it. Sorry, I
misspoke the angle as 7° earlier. That's where I set the saw to cut them,
but the total angle is twice that. The only things different about this
method is that you need to cut low angle shims, make a scraper to
accommodate them, and scrape the crack by hand. I haven't used a router and
straightedge simply because I don't find absolutely straight cracks in
soundboards and I can easily follow the crack freehand with the scraper. 

Nothing wrong with go-bars though, I use them every time I install a
soundboard, to clamp the panel to the cutoff bar. For shims, instead of
using the ceiling, how about clamping a 2X4 on edge across the top of the
rim and ripping some scrap to roughly the cross section of a Popsicle
stick, cutting them to length as you need them, and using them between the
2X4 and the shim. Quick, simple, and disposable. I used to do this before I
started using lower angle shims. Gotta go to work now, but if anyone's
interested, I think I have a couple of ways to rough-calculate go bar
pressures from given dimensions, and I'll put something together and post it.

Ron N