Tillering heat treating and backing

[DC]

I'm making a Maple backed Cascara RD. At the moment the limbs are 1 3/4" wide tapering to about an inch at the tips. They are 5/8" thick tapering to  something less than 1/2" at the tips. It's been heat treated to lock in the reflex. I think I've read that I should tiller the bow somewhat before I glue the backing on but in order to prep the back I have obviously violated a bunch of rings. Cascara seems to be a bit tension weak so it would probably break trying to tiller it. If I glue the back on now the bow will be way more than the 40ish# I'm after and I would probably scrape off most of the heat treat. I can't heat it after I glue the back on. It's my first Cascara bow so I'm kind of guessing at limb thickness. I'm stuck in this vicious circle and the only thing I can think to do is not worry about the heat treat. Is there an other way out of this?

[Pat B]

What glue do you use. Some of the epoxies can take a bit of heat without being harmed.

[DC]

West Systems. I did some looking. The Tg of 105/205 is 142°f but it will take 200°f and return to a hard, just as strong as before state. It will have varying degrees of flex between those temps. This is handy to know for little adjustments like string alignment. Thanks for making me look that up

I don't know if it would stand up to a heat treatment though.

[leonwood]

You can use a thin temporary backing and glue that on with hide glue. This will easily come off when you finish tillering the belly slat and do the final heat treat. You can cut a quarter sawn white or red oak as temporary backing. Really cheap and easily done.

[DC]

Good idea. I guess you can just wash off the old hide glue so it doesn't contaminate the epoxy.

[Pat B]

Just remember that your car can reach 142deg on a hot day in the sun or your bow leaning against a tree in full sun. I've seen glass bows that were left in a hot car braced. Not pretty.
 I guess if you keep the bow clamped to the form until it is completely cooled you might be OK.