Tri-Lam Belly Replacement

[EvilDogBeast]

Did a little searching and wasn't able to find anything conclusive.  I laid up a tri-lam the other day with an Ash back, Cherry core, Sapele belly, and a Wenge riser.  Long story short, the Sapele developed a chrysal in one limb and cracked through stopping at the core.  I went ahead and sanded the entire belly off, then laid up a new belly made of Maple.

Has anyone had (or know of) success with this process?  Not that it would discourage me from trying one way or another (my first board bow cracked across the back mid-limb, it now has a 3-ply fiberglass layup under an epoxy hardened serving string repair).  Any information or opinions would be appreciated!

[rainman]

Grind off the Sapele, get a lam of Ipe or Osage, and glue back up.  I don't believe the Sapele is strong enough for a belly lam.  You could also use Bamboo.

[mwosborn]

Don't know why you would not be able to make it work.  How thick is the ash and cherry?  Is the cherry tapered?  How thick is the maple you plan on using?

[EvilDogBeast]

The whole thing was way too thick to start with.  Ash is 1/8", cherry is 3/16", and the sapele was 1/4" to allow for tillering.  Nothing was tapered at the start, but the cherry is now (did it after I sanded off the sapele).  The new maple lams are about 1/8" to bring the draw down closer to 40-ish pounds.

[Dan Landis]

I've done both a back and belly, not on the same bow.  The back was hickory, replaced with another hickory, that one cracked also.  Plan to replace with bamboo the next time.  The belly that I replaced was bamboo backed, tapered  hackberry core, with an osage belly.  The osage got too thin because my core lam was too thick.  I ground the osage off and also reduced the core lam, then glued on a new osage belly slat on both limbs and retillered.  It made a real nice shooting bow, just under 50 @ 28"  Hope this helps.

[mwosborn]

Those numbers seem good depending upon width and length.  With only 1/8" thick belly, you won't have much wiggle room during tillering.  Pictures when it is done!

[Pat B]

Use a compression strong belly wood like osage or ipe like rainman suggested.

[Roy from Pa]

I've replaced the belly lam a few times. It's a project but can be done. Osage is the best belly wood.

[EvilDogBeast]

Thank you everyone for the input!  It settles my mind a bit to know that this is possible.  The next one I do will definitely have ipe or something similar for the belly lam.  I'm going to see this one out with the materials at hand just to see if I can do it, too hard-headed to do otherwise.  Sorry for not mentioning it in the beginning, but it is 68" overall, 66" nock-to-nock, pyramid style starting @ 2" straight taper down to 1/2".  I would have liked to leave the maple a little thicker, but I wasn't sure I'd be able to bend it up the fades of the riser without cracking it if it was much thicker.

[EvilDogBeast]

Got it all cleaned up, it's an ugly duckling for sure but I love it all the same.  Only thing is, it seems to have taken an absurd amount of set after re-tiller.  Started out with 2" of reflex and I'm all the way down to 1.5" of string follow, 30# @ 28".  Oh well, guess the wife will enjoy shooting her new longbow!  

Pictures to follow once its all cleaned up.

[mwosborn]

They will get better.

[KenH]

It just dawned on me that I don't know what glue you tri-lam builders use for lay-ups -- Smooth-On??  Or a glue like Titebond??

[Pat B]

I've used TBIII, Urac and Weldwood Plastic Resin.

[EvilDogBeast]

I used TBIII on this one.  Works well but is a little messy since it won't cure wrapped in plastic.

[Roy from Pa]

Unibond800

[Dan Landis]

I use smooth on.

[KenH]

Thanx guys -- that pretty well covers the spectrum!

[Bob W.]

I Used Unibond 800. Now I  am  using Pro Glue. James Parker told me about it at the Classic and so far I have glued up  a BBO trilamb and Bamboo backed Yew and am very pleased with it!