optimal glass thickness

[arachnid]

Hi guys.

I`ve built several hybrid ongbows with 0.8mm thick Bearpaw powerglass with no issues.
I`m about to order s`more glass and I wonder what`s the optimal glass thickness. Bearpaw has the powerglass in  0.030 inches, 0.040 inches, 0.050 inches thickness`. Which should I get?

[monterey]

I think a good approach is to consider glass thickness based on it's percentage of the total stack.  What that ideal percentage is, I'll leave for the experts to say.  

[kennym]

I did a survey many years ago, and on longbows it was in the 20-25% range.  I have no real testing on it tho, but that seems to work.

[C. Johnson]

Well, for my bows, I use .030" for light draw weights, less than 30 pounds.  I use .040" for anything up to about 45-50 pounds, and .050" for anything heavier.

I'm certainly no expert, but having more glass makes me feel more comfortable with the integrity, stability, and longevity of the bow.

[beachbowhunter]

Anybody have a rule of thumb for glass ratio on recurves?  I'm about to build my first set of recurve limbs and have no idea what weight they will come in. I'd rather be light then too heavy. I only have 0.040" glass. Was wondering if I should grind them down for something in the 45# range.

[arachnid]

Originally posted by kennym:
I did a survey many years ago, and on longbows it was in the 20-25% range.  I have no real testing on it tho, but that seems to work.

Well, since I don`t have easy excess to glass (I need to ship from Germany to Israel) I`d like to have "one size" to match all my bows.

[kennym]

If I could only do one size fits all, it would be .040 I guess....  

Or order .050 and grind to what I wanted....

[arachnid]

OK, that`s what I was thinking.
Thanks you guys.

[TradBowyer]

yes as stated above. For recurves, I always used 040 glass unless over 60# then I went 050. Like Kenny said, 040 is the best all around. Heavier glass is more durable but you lose speed because its heavier. I always saw increases in speed when dropping from 050 to 040.

[fujimo]

very interesting TradBowyer, did you ever notice if there was more set with the lighter glass on heavier bows?

[arachnid]

Originally posted by TradBowyer:
yes as stated above. For recurves, I always used 040 glass unless over 60# then I went 050. Like Kenny said, 040 is the best all around. Heavier glass is more durable but you lose speed because its heavier. I always saw increases in speed when dropping from 050 to 040.

I used 0.03 glass for all of my longbows and there at the 45-55# range. It seems to work fine.
Question is, when I switch to 0.04 glass, how much drop in cast will I get? I'm willing to sacrifice a few FPS for afded durability.

[Mark R]

It somewhat depends on the design,but I think .040 would be best, maybe even better cast,your stack with .030 glass maybe thicker core wise than with .040 glass, both stacks being equal, and the glass has more performance qualities than the core,IMO.