Can someone explain this to me?

I know that when you put limbs on a shorter riser it changes the draw weight of the limbs-- have been through this with Bob Lee TDs. I am looking at a pair of Morrison limbs for my Shawnee A  riser, and the owner says that Bob's limbs are the same weight on all lengths of his risers. How does this work?

[Orion]

Simple, the current owner is wrong.  Assuming the same set of limbs on different riser lengths, the poundage will decrease with the longer riser (longer bow) and increase with the shorter riser (shorter bow). May only be a pound or two per 2-inch increment, but  there will be a difference.

[lpcjon2]

You may get a more detailed answer if you post it in the bowyers bench.

 http://tradgang.com/noncgi/ultimatebb.php?ubb=forum;f=125

[wingnut]

Actually the current owner is correct.  Bob builds his risers to make the limbs weight the same on each of the riser lengths.

We do the same thing with our 13,15 and 17" risers.

Miker

Yes, but how do you do that?

[mooseman76]

Maybe something to do with the limb pad angle???

[tenbrook]

Originally posted by mooseman76:
Maybe something to do with the limb pad angle???

BINGO!  

[Orion]

You could change the limb bed angle a bit from riser to riser,  but they still wouldn't yield the same weight with widely divergent limb lengths, say 56 inches to 66 inches. For example, changing the limb bed angle from an A riser to a B riser might make a set of 56-inch limbs equal on both risers, but those same angles wouldn't work for a set of 66-nch limbs because the limb geometry is different than a set of 56-inch limbs.

Now I suppose it's possible to change the limb butt angle/limb wedge on each set of limbs such that the angle at which they leave the riser is just a tad different for each set of limbs to accommodate for their different lengths.  This would be the only way of accomplishing it that I can think of.  Don't know if Bob does this or not.  Most bowyers do not.

I no longer own a Shawnee, but when I did own them, when I put the limbs on the A riser that I normally shot on a B riser, they dropped nearly 2# in weight.  

Maybe Bob will chime in.

[ron w]

On some of the Metal risers I have had it was marked it the limb pocket +8 +7 or whatever it was. That was added to the limb weight. My Zipper seems to be what the limbs say....40# is 40# plus the adjustment to max poundage,usually 3-5#.

[Orion]

We're not talking ILF limbs here.  Of course, there's adjustability with those.  The limbs are bolted tight on a Shawnee.