Limb Lam Thickness -vs- Draw Weight

Started by huntwithastick, July 10, 2010, 01:05:00 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

huntwithastick

Can anyone give me a good estimate on how much increase/decrease in draw weight can be expected by increasing/decreasing the thickness of the limb?

Thanks.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery - Winston Churchill

"Tough Times Don't Last, Tough People Do"

Apex Predator

It greatly depends on design.  The more curvy designs require less lam stack.  The same can be said for shorter designs.  On my 66-68" straight and slight R/D longbows, it usually is 2.5# per .010 lam thickness.
I didn't claw my way to the top of the food chain to eat vegetables!

huntwithastick

I guess my question was for one specific design - say D/R design!  Thanks for quick input on the straight and R/D designs!
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery - Winston Churchill

"Tough Times Don't Last, Tough People Do"

Apex Predator

Do you have photo of your form.  Riser length?  A lot of variables!  Go to Binghams or Three Rivers Archery websites.  They each have a limb thickness chart for the designs they offer.
I didn't claw my way to the top of the food chain to eat vegetables!

Swissbow

I got an excel table from Jason for a moderate R/D-design. It has worked very good so far. You can get it in the download section on my website.
 
www.swissbow.com

----------
Andy

Jason Scott

Are you copying an existing bow? I have a cube root formula that I can send that will get very close to a new weight for any style bow you want to copy. All you have to do is precisely measure the bow you want to copy, enter its stack, weight and your target weight and it will give you the new stack height. You have to rebuild to exact except for the new stack.

Jason Scott

Using the formula you can deduce how much stack changes differ in weight.

swamp ghost


Jason Scott

I have it in Excel. I will have to email it to you.

Jason Scott

I don't know how to attach a file using the TG email feature. Your email is not listed. Respond to my email and I will have yours.

Trick

Jason,

I would appreciate it if you could send me the formula also.

Thank you,
Patrick

huntwithastick

I started out w/the Bingham pronounced design.  I like short risers though, so shortened my riser to 14".  The three times I've tried to order from Binghams and tell them my dimensions I've come in significantly off target on weight.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery - Winston Churchill

"Tough Times Don't Last, Tough People Do"

Jason Scott

I'm guessing you came in lighter than you wanted. Maybe you could just order a stack that is 15 pounds heavier than your target weight according to their normal design and just not tell them about your shorter riser. After your layup with the 14" riser the 15 extra pounds will go away with the 4" loss in riser length. Not sure what their standard riser length is though, assume its 18". Basically just order 3 to 4 pounds heavier for every inch shorter your riser is than theirs.

huntwithastick

Whoooohooo! Eureka! I had a set of partially finished limbs that I got around to finishing and they came in at 55lbs.  So, now I have my baseline and can adjust from there!  Thanks for all the input guys - I do appreciate it.
Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery - Winston Churchill

"Tough Times Don't Last, Tough People Do"

Contact Us | Trad Gang.com © | User Agreement

Copyright 2003 thru 2025 ~ Trad Gang.com ©