Hill style lams

[scottm]

If your tapering lams for a Hill style bow with a flat riser,im understanding that you leave the butt ends flat for the length of the riser to mate well with the flat surface.If im going to grind my tapers then flatten 8" on each end of my lams, is this going to effect how i calculate my stack?In other words should i measure my stack at the taper,or measure as normal before i grind the flat spots?Thanks I hope this makes sense,Scott

[kennym]

I would use the butt thickness you have before paralleling the end.The rest of the lam in the working limb will still be the same.

 Or put reverse taper in the proper amount on your form to make up for it.

[scottm]

Thanks Kenny!

[jsweka]

Take Kenny's advice and go with the butt thickness when calculating the stack.  That way it will always be the same whether you have your tapers on the back of the riser or on the belly.

The last bow I made was the first time I put all laminations on the back of the riser(only the belly glass came up the fades).  I was worried about this too, but I just did a little sanding by hand with a sanding block once I spliced the two tapers together at the butts and checked to see if the riser laid flat and it did.  If you think about it, in 8" there's only going to be 0.016" difference in thickness using 0.002 tapers.  Once you put it in the form the fadeouts will move that much and take up any space.

[bigbob2]

Strange as it might seem I grind to the centerline of each lam and lay up that way.so my tapers start from the center. Might not be the 'done' thing but it works very well and the force draw curves are excellent.

[canopyboy]

Originally posted by jsweka:
If you think about it, in 8" there's only going to be 0.016" difference in thickness using 0.002 tapers.

The Hill bows I have measured have a total taper of 4 to 6 thou.  5 thousandths (average) over 8" is .040, or a little over 1/32 of an inch.  Seems like a lot, I thought I'd see how it clamped up dry before I started flattening.  

But....if you make a form for 1" of stringfollow on a 72" bow with a parabolic arc, you end up at about .049 at the 8" mark.  Just food for thought.

[jsweka]

True. True. Definitely depends on the taper rate you use.

[scottm]

Thanks for all the great info!