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Main Boards => The Bowyer's Bench => Topic started by: Si on December 21, 2012, 11:23:00 AM

Title: Sanding glass to lower weight
Post by: Si on December 21, 2012, 11:23:00 AM
I have made all types of bows and repaired many bows but never needed to lower bow weight by sanding back or belly glass. Experienced input would be appreciated. Thanks
Title: Re: Sanding glass to lower weight
Post by: grizz on December 21, 2012, 12:46:00 PM
Here goes my nickels worth. If the limb width will permit, I will take some off of the sides, My experience has been that you tend to dampen the limbs recovery by thinning the glass, losing some performance.
Title: Re: Sanding glass to lower weight
Post by: Tom Leemans on December 21, 2012, 02:47:00 PM
I'd either narrow or trap a little more before thinking about sanding the glass.
Title: Re: Sanding glass to lower weight
Post by: macbow on December 21, 2012, 07:23:00 PM
On longbows I tend to go for trapping and reducing  sides as needed.
On recurves I am more Leary of reducing sides.
If the glass is thick enough sanding the surfaces equally is probably the best.
Formula on just wood is 8 to 1 thickness . Removing .001 on the faces is the same as removing .008 on the width.
Title: Re: Sanding glass to lower weight
Post by: jsweka on December 21, 2012, 09:08:00 PM
I agree with the above - reduce the width to reduce the weight.
Title: Re: Sanding glass to lower weight
Post by: kennym on December 21, 2012, 09:22:00 PM
I like to reduce width and trap em also, I'd say as a last resort, use a sanding block and count strokes on each limb.
Title: Re: Sanding glass to lower weight
Post by: Roy from Pa on December 21, 2012, 09:48:00 PM
I don't make glass bows. But that glass isn't all that thick. I would reduce weight by sanding an equal amount off the sides of the limbs, SLOWLY, or trapping the back of the limbs. The only glass bow I ever attempted was a kit from Binghams. The guy teaching me liked a straight limb taper, which I do also. So instead of following Binghams limb profile layout, we did a straight taper. My bow came in 10 pounds light. After the loss of weight, I studied the limb profile they suggested. The way we did my limbs was 1/4 inch narrower than what they suggested. There was my weight loss. So therefore, yes you could reduce the weight of the bow by reducing the width of the limbs. But that also could depend on how narrow your limbs are to start with:) You even more confused now?
Title: Re: Sanding glass to lower weight
Post by: Swissbow on December 22, 2012, 05:39:00 AM
I agree with Kenny. Go slowly and try to sand the glass as even as possible. Check tiller and draw weight regularly, because the weight might drop very quick.

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Andy