Lamanation stack distribution question.

[Tim Y]

  I’m planing a bow build, using Kenny M’s formula, for a .345” total stack thickness,
There are two tapered lams in the stack, one is .060”thick @ .001”taper (belly) and other is .135”thick @ .002” taper (back).
   So…why such a difference in thickness of these tapered lams? Why not split the thicknesses more evenly. Like one .1” and the other .095” and use .0015” tapper on each instead of the .001” and .002” tapered lams. The total thickness and tapper are the same and it seems that the ’’thin” tip end of the limb would be more functional and elegant.
   I have no intention of reinventing the wheel, but when I grind these tapered lams one set seems needlessly thin at the tip end.
By the way the stack looks like this:

 -.040 Bear Paw clear glass
 -.035 Parallel maple lam
 -.135 @.002 tapered boo
 -.060 @.001 tapered boo
 -.035 Parallel maple lam
 -.040 Bear Paw clear glass
45# goal with Kenny's modified form.
   Another question. Keeping the total stack thickness the same, .345”, how would changing the thickness of the two parallel lams affect performance?
   Thank You,
   -Tim Yanasak

[Bvas]

Grinding both sets at .0015 would be perfectly fine.  I would bet that most guys don't have sleds for this.  Most probably only have a .001 and a .002 sled.

You can adjust the thickness of the lams, and probably not effect performance much if at all as long as the total stack remains the same.  A lot of guys make one set of parallels and one set of tapers slightly thicker.  These will be run on the back of the riser.  This leaves the thinner lams for the belly side to make it easier to bend them into the ramps.

Hope that made sense

[kennym]

Hey Tim,

First, .365 will get you about 55@28 

Then, I make the .001 taper thinner so it bends up the ramps easier, but if you are doing a lam  thru riser design like the build on my site, toy can split thicknesses evenly.


I can't tell that changing thickness makes a difference, once glued up it is a composite structure. 

[Tim Y]

Thanks for the response guys.
    I see now that the thiner lams were designed to bend more easily up the riser ramps on the belly side of the bow.

-KennyM, thanks for spotting my misprint ".365" I meant ".345" for the total lam stack thickness(I changed it in the original post.
   And yes I like the idea of the lam through riser design, as you did it on your site.
-Bvas, I am like most guys, I have use tapered lams that I purchased (from KennyM) to build a .001 and a .002 tapper sled. But tomorrow I will try to build a .0015 sled. we'll see how that works out.
  Thanks again,
  -Tim Y

[Tim Y]

   Ok, I spent the early morning in the shop. I began to make a new .0015 taper sled, but that turn into more work then it was worth. I went back to the .001 and .002 taper sleds and ground sets of [email protected]" taper and [email protected]" taper. This was my first go at using the tapering sleds and it went well. I was surprised how close to specs they came out. Advice to any other first-timers, go slow, a little at a time.
   I also cut some parallel veneers out of quilted maple that I was given. I ground them to .035 thickness and that turned out well too.
  Thanks for all the help.
  -Tim Y

[kennym]

Building  sleds from scratch is a job.5 !! LOL I can get you a set of lams or a sled in .005, .0015, .0025 or about any you want tho! 

Good looking lams there! Should be sweet when done!