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Main Boards => The Bowyer's Bench => Topic started by: kennym on March 14, 2020, 12:51:13 PM

Title: I need some input
Post by: kennym on March 14, 2020, 12:51:13 PM: Seems I and some others have had some bows come in heavy with Bearpaw clear glass. Has any bodies results changed?

I’ve been telling folks to add 5 if using but now I’m coming in 10 heavy , more than once !!
Title: Re: I need some input
Post by: monterey on March 14, 2020, 04:35:51 PM: I thought it was that they could come in light??

My only comparison would be two identical bows about 1 1/2 years ago. One gordons colored glass and one BP clear. Identical stack thicknesses and the BP was about 4# lighter with both bows in the 40's.

Hope to hear more about this.
Title: Re: I need some input
Post by: kennym on March 14, 2020, 05:21:13 PM: Yes, I was coming in light, but now heavy, maybe its something I did , but trying to figure it out.
Title: Re: I need some input
Post by: monterey on March 14, 2020, 05:24:13 PM: Was the glass off a new ring?
Title: Re: I need some input
Post by: kennym on March 14, 2020, 05:50:20 PM: Yep, two different ones came in heavy...
Title: Re: I need some input
Post by: Flem on March 14, 2020, 06:15:43 PM: As a dealer, can you contact them directly and find out if they changed their manufacturing process?
It would be interesting to know if and what they might have done.
Title: Re: I need some input
Post by: kennym on March 14, 2020, 06:36:51 PM: I have an email to my supplier but prob won't get an answer til next week, especially if he needs to talk to the factory.
Title: Re: I need some input
Post by: Flem on March 14, 2020, 09:01:00 PM: I was just now looking at the Bearpaw website. The glass to resin ratio has not changed, unless they have not updated the info. But it does say that they changed the thickness from 1.2mm to 1.29mm.
Title: Re: I need some input
Post by: kennym on March 14, 2020, 09:10:17 PM: Still checks at .040 on the dot
Title: Re: I need some input
Post by: Robertfishes on March 14, 2020, 11:25:12 PM: Kenny, maybe you can do a flex test using the same hanging weight each batch? keep a log book just like your build book and maybe you can get closer??
Title: Re: I need some input
Post by: Flem on March 14, 2020, 11:28:22 PM: Thats interesting. Sound like their QC need a revamp. 1.2mm=.047 and 1.29mm=.050.
Either one is way off from what you have in hand Kenny
Title: Re: I need some input
Post by: kennym on March 15, 2020, 12:02:51 AM: I’ve done some redneck flex testing against Gordon’s Robert, but I don’t have any of the older BP on hand .

Flem , that is the thicker roll which checks at .050” but I don’t use much of it on my bows ...
Title: Re: I need some input
Post by: Shredd on March 15, 2020, 12:40:29 AM: Just a wild shot but you could try weighing 2 pcs of glass... Glass is heavier than resin... Could show if one has more or less glass in it...
Title: Re: I need some input
Post by: bigbob2 on March 15, 2020, 05:10:03 AM: All mine with BP mostly came in light,
Title: Re: I need some input
Post by: kennym on March 15, 2020, 08:48:35 AM: Good idea Shredd, I will do that.

Bob mine were too until they weren't .

I'd seen some stuff about the bows coming in heavy but hadn't had anything but light til now.

I'm checking all my math and going back to notes from known bow weights I've built now.
Title: Re: I need some input
Post by: kennym on March 15, 2020, 09:22:38 AM: The redneck flex test, 12” out from bench, clamped flat on bench with a board, both clamps same weight, both glass same dimensions, bp is the closer one and somewhat stiffer.

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Title: Re: I need some input
Post by: Shredd on March 15, 2020, 03:25:36 PM: Two other things could change stiffness... The glass could have been under more tension when they produced it or the resin could be different... There could be a list of other things also such as cure time and cure temperature whether the machine operator was out on a binge the night before...
Title: Re: I need some input
Post by: kennym on March 15, 2020, 03:34:58 PM: Right on Rich, I have a spine checker made to check against Gordons as that is what I made my stack charts from.

Sure nuff, the .040 is roughly 5 lb stiffer than Gordons where it used to be about 5 lb lighter.

The .050 checked exactly same as Gordons , and the Gordons is all real consistent between clear and color glass.
Title: Re: I need some input
Post by: Flem on March 15, 2020, 05:01:12 PM: Did you ever weigh some samples Kenny? Like Rich pointed out, glass is heavier than epoxy, like twice as heavy.
Title: Re: I need some input
Post by: kennym on March 15, 2020, 05:12:02 PM: I didn't yet, I was so much interested in spine I forgot, but that may go right along with the spine issue.
Title: Re: I need some input
Post by: Holm-Made on March 15, 2020, 05:30:35 PM: My bows have been coming out 6-8# heavy. I thought it was because I was putting stabil core under each veneer. (Still keeping the same total stack height). Maybe it is the new rolls of glass? You got me thinking.
Title: Re: I need some input
Post by: Crooked Stic on March 15, 2020, 05:54:00 PM: as long as you reduce the core the same as the stabil core taking its place it should not raise weight. I would think that BP has a big enough customer base that they should at least try to get con sistancy from roll to roll
Title: Re: I need some input
Post by: kennym on March 15, 2020, 07:00:16 PM: When I started using bp I found I had to add 5 lb to stack to match Gordon stack , the last roll that I used a little from I was coming in heavy so I have been trying to figure out what was going on.

I built a tester today and checked several Gordon to get a kind of standard , then checked a pc of bp from the roll I’d been getting heavy on. It was some heavier , about like .003 thicker Gordon’s by my estimation. So that would be like adding .006 worth of glass ...

I also checked a pc of edge grain maple .040 lam just to see how it compared to glass.

My final theory is: between the stiffer bp and the 5 lb I’d been adding for the earlier bp is where I was getting the 10 lb over on bows .
Title: Re: I need some input
Post by: kennym on March 15, 2020, 07:01:36 PM: The bp .040 came in about 1/3 of the way up to the .050 Gordon’s , the bp .050 and Gordon’s .050 were identical .
Title: Re: I need some input
Post by: Crooked Stic on March 16, 2020, 07:36:04 AM: I am SO confused. :scared: I really hate the guessing games sometimes.
Title: Re: I need some input
Post by: Mad Max on March 16, 2020, 07:56:20 AM: So the edge grain maple added weight also ??????????
Title: Re: I need some input
Post by: kennym on March 16, 2020, 08:49:41 AM: Sure but was just checking its stiffness compared to the glass. Prob shouldn't have even mentioned it. LOL

Edited to show that... :)
Title: Re: I need some input
Post by: Mad Max on March 16, 2020, 09:47:43 AM: :thumbsup: