Belly versus Back thickness (Tri Lam)

[Wolftrail]

(Wood Bows)
If the belly and back lams are the same thickness,  would you remove material from the belly or back to achieve proper tiller.
Is it safe to say that the back should always be thinner than the belly lam.?  And what difference does it make.?   :confused:

[Pat B]

With boo backing you are limited to it's original thickness, generally about 1/8" at the fades at the crown, sometimes tapering to 1/16" at the tips. For hickory backings or other hardwoods backings I start with 1/8" but sometimes do some scraping on the back if needed. Backings can be tapered or parallel.
 Most of the tillering on an all wood tri-lam would be on the belly. Ideally most of the tillering is figured out before glue-up with adjustments made by scraping the belly.

[Wolftrail]

So you are saying all thickness's been equal always remove material from the belly.

[Bowjunkie]

Whether bamboo or hardwood backing, I generally make the backing the thinnest piece, usually less than 1/8" at the handle, if possible. Some smaller diameter boo makes that tough. And I have backed woods such as cherry with hickory and then reduced it to barely 1/16" so it wouldn't overpower the cherry on the belly.

The center lam and belly lam are pretty close to the same thickness in my trilams, though I tweak those depending on need. The center is tapered and the belly parallel... so naturally, the belly lam becomes a little thicker than the other two the farther on out the limb we view it. This allows for adjustments to be made in tillering and weight reduction on the belly..... though there shouldn't be much of either of those necessary if we did an adequate job of everything previously.

Some gentle tillering can be done on the back of a bow that's backed with quartersawn hickory or maple for instance, but I almost always do it on the belly.

[Wolftrail]

"The center lam and belly lam are pretty close to the same thickness in my trilams, though I tweak those depending on need. The center is tapered and the belly parallel"

Thanx