Trilam

[billy dryden]

Any one build a trilam with a hickory back and belly? thinking about trying one with a walnut core. would like to make one in the 52# to 60# range.

[monterey]

C'mon Roy!

[Bowjunkie]

You'd do better to provide some info on the type of bow you want to make and then ask more specific questions.

[billy dryden]

Thinking about a 64 or 62" reflex deflex. Is it posible to run the belly over the fades of the riser more like glass bow?

[Bowjunkie]

Well, the short answer is yes, it's possible, but consider that with a glass bow, the lams(wood and glass) need to be adequately thin, usually less than .050" or so, to affect the degree of arc/bend in the fades of many of their designs... especially longbows with shorter risers.

In a trilam, the belly lam needs to be of adequate thickness to make weight, resist compression forces, and allow for wood removal during tillering... and some of that tillering can need done in the area of the dips. That needed thickness may either dictate whether or not it can be pulled down into those curves, or force design changes/specs so it's possible. I'm not saying it can't be done, just that it would seem to unnecessarily complicate the build, and there are things that need to be considered and coordinated.

[Roy from Pa]

Yes a hickory tri lam is possible but I wouldn't run the belly over the fades.

[billy dryden]

what kind of width and thickness would you use to make a high 50's to 60 pound bow? and what kind of lam thickness on each lam?  Roy you seem to be the expert on this type of bow. Any other tips on building a trilam?

[Roy from Pa]

No expert but make the fades 1 1/2 wide and taper the limbs to 1/2 wide at the tips. 5/8th thickness should be plenty. The hickory backing should be straight grain 1/4 sawn about 1/8th thick. I make the my belly lam 1/4 thick and 1/4 thick for the core lam and then taper it to about 1/8th at the tips. The boo is 1/8th thick tapered to 1/16th at the tips.

[billy dryden]

sounds good. that will give me a starting point for getting material together. One other question can i cut a shelf to center on one of these or should i stop short of center?

[Roy from Pa]

I wouldn't cut very much out if any. I make a rest out of leather.

[LittleBen]

I cut all mine basically to center. If you build your riser like a glass bow (i.e. Deep from back to belly) you can do basically whatever you want..

Remember, lots of takedown bows have no glass in the riser and are cut to center.

[monterey]

A little of on a tangent, but if one were set on running the belly up the riser ramps, would it be practical to comprise the belly "lam" of three thinner lams?

Guess that would make it a pentalam?

[billy dryden]

i kinda had the same idea about a few thinner lams. but don't know if it would work.

[Bowjunkie]

Monterey, yes, that could be done, divide that 1/4" belly lam into three .080" parallel lams. Although it would increase the likelihood that the outermost lam was worked through into the glue line while tillering and/or seeking target weight. We'd be getting close enough to the realm of glass bow making that stack height should be closely regulated to predict the resulting draw weight and eliminate some of hurdles. I also don't know how such a thin belly lam would do with compression.