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Main Boards => The Bowyer's Bench => Topic started by: wolfcoach on January 09, 2019, 07:33:26 PM

Title: Bimgham Takedown Recurve
Post by: wolfcoach on January 09, 2019, 07:33:26 PM
I have a 60" takedown recurve that I built several years ago and have been thinking about building a new riser for it.  My question is can I shorten the riser by 4 inches, keeping the angle of the limb mounts the same without changing the draw weight? 
Title: Re: Bimgham Takedown Recurve
Post by: Roy from Pa on January 09, 2019, 08:16:14 PM
It will increase the draw weight.
Title: Re: Bimgham Takedown Recurve
Post by: Bvas on January 09, 2019, 08:28:13 PM
It will increase the draw weight.
Yep
Title: Re: Bimgham Takedown Recurve
Post by: wolfcoach on January 09, 2019, 08:43:30 PM
I thought that it would but wasn't sure if i kept the limb angle the same.  Thanks
Title: Re: Bimgham Takedown Recurve
Post by: TradBowyer on January 09, 2019, 08:56:48 PM
wolfcoach,
it will change because you are shortening the overall length of the bow by 4". if you want to do that and keep the same draw weight, you have to change the angle of your riser 'pads' to compensate for the decrease in length. Changing the angle of the pads increases or decreases your pre-load on the limbs. a steeper angle will push the limbtips forward of the handle and increase your pre load which will increase your poundage. A lesser angle pulls your limb tips back toward the riser and will decrease your preload which will lower your poundage
Title: Re: Bimgham Takedown Recurve
Post by: Crooked Stic on January 09, 2019, 09:26:00 PM
It will increase it but not as much as shortening the limbs by 2 in on each end. 4 in. may get you 6-8 heavier. if you are making a new riser you can change the angle of the pads.
Title: Re: Bimgham Takedown Recurve
Post by: Brian from GA on January 12, 2019, 04:44:30 PM
You're changing the angle of the string to the nock during full draw.  With a shorter bow and all else the same, the bow will become less effective because you increase that angle.  Think about it like this, the limbs do more work when you pull them into an arc.  However, when you get past a certain point, you start drawing the limbs back to you as opposed to in towards the handle.  This is called stacking.  You get less arrow velocity for the amount of energy you put in.  Every bow does it, but a good design minimizes it. You could mitigate it on the shortened bow by decreasing the set back angle in the limb pocket and adjusting your brace height a bit.  I've never done it, but it's theory straight from TBB.  Good luck!

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Title: Re: Bimgham Takedown Recurve
Post by: Crooked Stic on January 14, 2019, 12:27:23 PM
Original ?? will weight increase Yes.