Limb trapping

[talkingcabbage]

Hey all.  I'm working on a 3 piece takedown recurve using Bingham's design.  My limbs came in like, 40lbs over what I wanted (shooting for 45 - 50lbs.)  I've been sanding on the glass forever, and got it down to about 60-70lbs, but I'm getting nervous and don't want to sand too much.

I'm thinking about trapping the limbs to reduce the weight more, but I'm not sure how much it'll drop.  What are the pros and cons of doing this?  Is it a good idea?  How much should I trap?  Does anyone have pics of trapped limbs so I can get an idea of what to do?

Thanks in advance to all for your help!

Joe

[Greg Szalewski]

I don't know where you are at now without pix, but can you narrow the limbs? I did that on the last one I made. The Bingham design for the limb width is much wider than what I ended up with. On a recurve trapping the limbs is probobly only going to get you a couple lbs.

[Jason Scott]

My experience is that you will only loose 2 -3 pounds by trapping recurve limbs. Five and your lucky. That is a huge reduction, I can't imagine trying to reduce any bow by more than %10 by sanding or trapping unless the width is reduced too. Then you run the risk of flipping the tips if you go too narrow. My third d/r bow came in somewhere around 100# if you can believe it. I had no idea at that time how much to increase and decrease stack for a weight change. I ended up making it so narrow and trapped that I couldn't string it.

[talkingcabbage]

Dang.  Well, i don't understand why it came in so heavy.  I followed the Bingham's charts to a T.  Does anyone know how much I can sand the glass before it gets too risky?  Also, should I be sanding more on the back, belly, or evenly on both?  As of now, I've been sanding them pretty evenly on back and belly.
The last Binghams design I did came in really heavy too, but a little sanding and it came down.  This one is REALLY heavy.  I'll try to get some pics up tonight so ya'll can see.

Just so you know, I've got it pulling about 60lbs at about 17".  So I've got a ways to go.  :(  

How much can I narrow the limbs and still be safe?  That's actually one thing that I thought of, but didn't know if it would work without flipping the tips or totally wrecking the limbs.

[JRY309]

Trapping the limbs will reduce weight alittle,but you have way too much weight you want to take off.I mean you are probalbly off around 30-40#,thats alot.

[Bob Tebeau]

That must be a big mistake on the way they ground your lams, you should call them for a refund. To get where you want you’ll have to take  3/8 to a ½ inch off those limbs and that may cause some new problems. I have ordered  a lot of kits from them  at the most they could be 5 to 8 lbs over sometimes.

[talkingcabbage]

I ordered these from someone else, not from Binghams.  I'm just using their design.  I've done this before and got my lams from the same person, and never had this much of a problem.  I'm thinking I may just have to end up with a 60# bow.

How much can I sand the glass before I should get worried?

[Jason Scott]

I go by the rule of staying off the face of the glass as much as possible except for preping the glass for finish. I stay away from the back glass. The only time I sand the belly face of the glass is to make fine adjustments to the tiller but we are talking about a pound or so. Just enough to get the limbs hitting home at the same time. I mostly round the corners off instead of sharp edges, that will take 5# or so most of the time. Usually never need to take more than 5 - 10 pounds off anymore. You may start to see the scrim in the glass if you take as much as .01 off the face of the glass and that can't be good.