Reducing weight on a lam recurve?

[LC]

I was just wondering how the most of you folks reduce weight on glass laminated recurves. I've been making my own for about ten years and just lately been making a few again. I had the weight down pretty good with the old Bow tuff glass but the last few I've been using the scrim glass. It's .003 thicker so I've been deducting for that but still coming in heavy. I've always in the past flat sanded the glass but thought I'd read some sand the limb edges to reduce weight also. Any opinions?

[Chuck Hoopes]

Ive been sanding the edges of my production glass lam bows for years.  Ive used this method to reduce wt. on at least 6 bows.  Simple, and works fine.  The one I have been shooting for the last yr. is a Howett Hunter, that is 55# reduced from 70# by edge sanding.  Took all of a 1/2hr.

[LC]

Well that sounds good Chuck. Cause thats about what I'm needing. How much are you having to take off the sides to reduce 15lbs? Like I said I've always flat sanded and hated to go much over 5lbs off that way.

[LC]

[Chuck Hoopes]

Can't give you an exact answer, as I took it off at two diff. times.  Also, diff. bow designs, limb widths etc. will effect the results that you get.  In general, my experience with ,-- a standard width glass bow of say 1 1/2" at the fades -removing a TOTAL of 3/16" from each limb, will reduce wt. 6-8 lbs. -- after this initial 3/16" removal, the effect of removing more will more quickly remove lbs.-- so if 3/16 only gets you half way to what you want, removing the same amount again is going to be way TOO MUCH.  After the first 3/16 go very slow, like 1/16 at a time and check for poundage.  Remove wood from the fades tapering in a straight line all most all the way to the nocks and than easy off some so as not to destroy the integrity of the nocks.  After any wood removal,  PULL THE BOW AT LEAST 20 TIMES-- , so it can settle in, and you can check the tiller.   If I had that Hunter w/ me, I'd measure the width for you.  I can tell you this--it's pretty darn narrow.-- and a great shooter.  I use only FF strings padded wn dental floss-- never a prob.  Good luck-- you can do it-- just go slow.

[Holm-Made]

The only problem with removing wood from the sides of the finished recurve is you have to do it evenly so one side doesn't become stronger then the other creating a twisted limb.  As said above go slow I guess.  Flat sanding is safer but takes a lot longer and your limited on how much weight you can take.  Have fun.  Chad

[snag]

I have watched an experienced bowbuilder sand the edges to bring down the weight by 5#. I don't know about 15#! Like Holm-Made said that could be a touchy situation.

[LC]

Well thanks for all the input! Well to honest this bow is so heavy that I'm not out anything if I can't get the weight down so I'm gona do something even if its wrong and chaulk it up to experience. I'll let you all know how it turns out.

[snag]

What do you guys think of sanding on the belly of the limbs to reduce that much weight. It seems like that would be a better way to go about it...? Of course you would have to be checking tiller as you go a long...and go slow.

[dave_570]

glass bows are for the most part pyramid bows. Sanding the belly and back i think is not a good idea because of the already thin thickness....with these type of bows the limb weight is not so much determined by thickness as it is by length and width.

[LC]

Well actually working on it today. Years ago 65# was just about perfect but for the last several years 50# works for me and I don't know how deader the local whitetail deer could be since the drop in bow weight. Anyhow figuring I had nothing to loose I took a dry earse marker and marked both limb edges up to about 7" from the limb tip. My limb tips are pretty narrow anyhow so I wanted to stay off them. The bow tillered perfect right after shaping the limbs so the first sanding only dropped the weight about a 1# so another run of the marker and so forth. I dropped it to 57# and then checked tiller. It was leaning a little so sanding just for that to true it up the weight came to 55#. I've dropped enough bows in the past to feel confident flat sanding now will bring me to my 50# top limit. Back to the shop.

[LC]

Well flat sanding both sides of both limbs brought me to my 50# top limit weight. Somewhere through flat sanding both limbs were equal stength in tiller so sanding one limb both sides to weaken it brought me in at 48#. PERFECT! Now if it holds up time will tell. Hope to stick some carp in a couple weeks if it proves it's worth for a season of bowfishing it's off to the woods this fall.

[Holm-Made]

Good job.  
Dave,
How much you can take off from flat sanding would be determined by how thick the glass is to start with.  If it is .050 glass you could flat sand it down to .040 and not be concerned as many recurves are built with .040 glass to start with.  Taking off .010 thickness off the belly and back would significantly reduce the poundage as it is a total of .020 of fiberglass, around 10 pounds worth of draw weight I would estimate.  Chad

[Texas_Plainsman]

Just found this post.  This is some good information.  Thanks for the posting.