Reducing draw weight of new blank

[lcamp319]

I am attempting to finish a laminated longbow blank.  Grip and overlays went well. I have not touched the back, belly or sides of limbs.  Tiller seems good for what I know.  Problem is draw is 43#@28”, I ordered 35#.  Talked to company where I got blank.  They said is not uncommon problem and that I can “trap the limbs” and bring down to desired weight of 35#.  Eight pounds seems like a lot?
Can I slowly, slightly and evenly sand the edges to bring weight down without schmuking it up?  Maybe a 1/32” off each side?
If it means anything, limb edges are square to sides and about 1 5/16” wide at fade outs.
Any recommendations appreciated.

[C. Johnson]

To "trap" the limbs means to make them into a trapazoidal shape. You'll want the back of the bow to be the narrower side.

What I do is file each side of the limb at about a 20 degree angle. Do an even number on each side. String the bow and check tiller. Rinse, lather, repeat.

You can sand the glass if necessary to bring down the weight a little more.  The trick here is to go slow and check your progress frequently.

I think you'll be able to get close to your target weight.

Good luck!

[BMorv]

I'm not sure the blank has glass, but the technique is still the same. Is it all wood or glass?  You shouldn't have a problem getting down that much if it's all wood.

[kennym]

For a glass longbow, unless made really narrow to start, 8# is doable, carefully!

Check tiller and limb alignment often!

If you have a 1.5" wide at fades bow and take 1/16 off each side, you will lose about 3-4#,  you can trap as described by Craig above to lose another 3 or so and final rounding of limb edges should get you close to 8# off. 

If you haven't done any tillering work, you might ask the company to exchange the bow for the weight you ordered.  8# off order weight is a bit much IMO

[Forwardhandle]

I'm glad you posted this thread I have bought every book on glass bow making I can find and in any of them very little is said on tiller technique or how to crown the glass how much how far etc , crowning I have often wonder how far you can go with out raising fibers ? Side tiller narrowing the width is pretty strait forward but crowning technique is not well explained it can be a little nerve racking never haven tried it . So I'm guessing the point is don't miss your weight by to far...lol

[kennym]

I refuse to sand the face of the glass, I know people do it, but it looks too easy to really screw up a limb or bow.........

[lcamp319]

Thanks for all the advice.  Things turned out well. I trapped/filed the edges of bows back at a guessed 20 degrees.  First time, filed glass down to edge of wood.  No weight change.  Second time, filed edges at same angle until maybe 1/32” of wood exposed. Very little weight change.  Third time, filed edges at same angle until 1/16” of wood exposed.  Bingo!! Dropped to 35# and is exactly where I wanted.  Would not have had the nads to try without all the advice.  Thanks.  Will make a perfect bow for newbys and form training.

[jsweka]

I refuse to sand the face of the glass, I know people do it, but it looks too easy to really screw up a limb or bow.........

My thoughts exactly!
We put the glass on a bow to keep the wood from blowing up.  Just seems stupid to then cut into the glass.

I've dropped bows 10+ lbs by narrowing the limbs and/or trapping and it obviously worked well in your case.