Author Topic: Question on belly lam  (Read 1305 times)

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Offline ccase39

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Question on belly lam
« on: January 18, 2019, 03:49:53 pm »
Hey guys, I have been on and off of this forum for several years now. I have made a dozen or so board bows over that period of time. In the past I did most of my work with Ipe and Osage backed with bamboo. I have also done several tri lams but never a belly lam.
This may be a dumb question but how do you tiller with a belly lam? I was thinking ipe or Osage core, bamboo back and am up for suggestions on what to use on the belly. Do you tiller first, sand flat, then add belly wood? Do I glue it all up first using a thicker belly and tiller from there? If so can you fade the belly into the core? I love the look of belly laminated wood bows but build alongs for these are hard to come by. I have gotten great help from you guys in the past so I figured I would ask.
Thanks!
Also if you have a link to a good build along that would be great.
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Offline Bayou Ben

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Re: Question on belly lam
« Reply #1 on: January 18, 2019, 04:46:14 pm »
You have done several tri-Lams but never a belly lam?  I’m confused.

Ipe and Osage are the best belly lams available as far as I’m concerned.  I wouldn’t use them as the core unless I had unlimited supply of Osage and ipe.

I like to taper all 3 equally; about .002”/inch each or .006”/inch total. If you don’t have the means to taper them accurately, then leave your core a little thinner and your belly a little thicker.  You can tiller all of your taper in on your belly lam.

TBB4 has a section on laminated bows with all the information you could ask for as far as tri lams are concerned.

Let us know if you need help on starting dimensions. 

Offline ccase39

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Re: Question on belly lam
« Reply #2 on: January 18, 2019, 07:36:42 pm »
It’s been a while so my terminology is off. The ones I made in the past were basically bamboo backed board bows with a very thin laminate in the middle. The ipe would be the thicker piece of the three when it was all said and done. This time I want to build one with the bamboo back, a center piece of ipe and thin belly wood. I will go back and make a couple like I used to for practice but I’m getting my ducks in a row.
Reading
The Traditional Boyers Bible Vol 1
The Bent Stick

Working on bow #7

Offline Dances with squirrels

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Re: Question on belly lam
« Reply #3 on: January 19, 2019, 05:20:29 am »
Yeah, I'm not sure what you're talking about either. Maybe this will help... maybe not.

When I make a bamboo backed trilam, I make the center lam and the belly lam approximately the same thickness at the bow's center. The bamboo backing is tapered. The middle lam is tapered, and the belly lam is parallel. The degree of taper of the middle lam is determined depending on how I want the limbs to work.

The belly lam is left parallel to allow a little more wood in thickness for some tillering or weight adjustment without rasping or sanding down into the glue line, but... BIG BUT here... the key to realizing some of the real benefits with these bows is to get your lam thicknesses and tapering accurate enough and close enough to final dimensions prior to glue up, that minimal weight and tiller adjustments need done later. Not unlike with glass and wood laminated bows, precision and record keeping are helpful.

The way I do it, the backing, middle lam, and belly lam are glued up in one shot. When it comes off the press/jig/caul, the handle piece is shaped to match the profile and then it's glued on.

The belly lam should be a wood that is great in compression resistance. If you want to play with different woods like cherry, walnut, sassafras, yew or whatever for the center lam, that's fine, but it's hard to beat osage or ipe for the belly. Although, boo/yew/yew or boo/yew/osage are great combos too. Lots of options.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline ccase39

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Re: Question on belly lam
« Reply #4 on: January 19, 2019, 05:43:29 am »
Cool I get the idea now. Any measurements for the thickness on each of these lams that will get me close? Is there a walkthrough that you recommend. I’m shooting fo 50# @ 28
Reading
The Traditional Boyers Bible Vol 1
The Bent Stick

Working on bow #7

Offline Badger

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Re: Question on belly lam
« Reply #5 on: January 19, 2019, 06:34:44 am »
The first few bows I made I had no idea what I was doing and I used 3 each 2"X 1/8" strips bought from the local Rocklers to make recurves. They came out around 45# plus a little at 64" long.