Author Topic: Sizing?  (Read 962 times)

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Offline gfugal

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Re: Sizing?
« Reply #15 on: March 20, 2017, 05:38:23 pm »
I can't speak for Pat but I did a little research on epoxies. I've used two-ton epoxy (30 min epoxy) and it works real well. It should hold at full strength up to 200 and it doesn't require a hot box, but its a little more expensive although readily available. There's other options like T-88 which may be cheaper. Anything made for boats like G-flex should also be good. But again I havenn't used them. Things like Weldwood, Unibond, Smooth On, Resincole are all similar and with good gap filling properties. I made a post about glues that generated good discusion that you can check out. Here's the link http://www.primitivearcher.com/smf/index.php/topic,59138.msg820090.html#msg820090.
Greg,
No risk, no gain. Expand the mold and try new things.

Online PatM

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Re: Sizing?
« Reply #16 on: March 20, 2017, 06:19:19 pm »
pat what epoxy do you use and where do you get it?thxs
I use System Three Gel Magic, G2 or T88 and West G-Flex and  610.

Do you have a Lee Valley store near you?

Offline bushboy

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Re: Sizing?
« Reply #17 on: March 20, 2017, 11:39:01 pm »
Yes,there's one in winnipeg thank's!
Some like motorboats,I like kayaks,some like guns,I like bows,but not the wheelie type.

Offline Hamish

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Re: Sizing?
« Reply #18 on: March 21, 2017, 05:21:34 pm »
Not all epoxies are created equal. You want one that cures to a glass hard glueline. Any of the known bowmkers epoxies are good as they have a proven track record of resistance to the strains subjected to a bow. Any thing else you are starting to take risks.
I have had a bamboo backed stave start to delaminate, immediately upon floor tillering. It was epoxy from a well known brand favoured by boatbuilders, which I had used many times before for tabletop edge gluing, ie a staic application.
You can also get into trouble at the handle lamination, fades if the epoxy is not good enough, the exposed end of the lamination will start to lift and delaminate. Proper bowmakers epoxies are strong enough to prevent this happening.

Online PatM

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Re: Sizing?
« Reply #19 on: March 21, 2017, 05:55:32 pm »
All of the ones  I listed are either recommended for bows or meet the criteria necessary and hold up
to the stresses.

What were you using?

Offline Hamish

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Re: Sizing?
« Reply #20 on: March 21, 2017, 09:51:44 pm »
Hi Pat,  I had problems with West Systems for delamination,can't remember the code, but it wasn't G Flex that's for sure. My stuff was a good glue for static joints in furniture. It was about 10years ago so they might not still be using the formulation, I had trouble with.
I also found it wasn't good for areas near the fades/handle riser- even not visibly bending, it still must undergo enough stress to start breaking down at the exposed joint.
I avoid any commonly available hardware store type of 24hr "strong" epoxy. I had the same problem with handles risers lifting at the dips, and I have even had Z spliced billets  start to come apart. Had to break the rest of the joint with a heatgun, soak and scrub of the residue with acetone, then re glue with a proven epoxy.

You can definitely get away with a more rubbery glue joint in a full length lamination as there isn't any exposed areas except at the tips which don't bend much.
The best test I have found is to mix up a small amont of epoxy on a thick bit of plastic like an icecream lid. When its cured flex the plastic around. If its rubbery and bends with the plastic base, it could cause problems in area for handle risers etc. If the glue snaps crisply and leaves a glass like fracture it should be strong enough for any application. Resorcinol and urea formaldehyde have the same characteristic glass like glue line, bullet proof results.

Offline vinemaplebows

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Re: Sizing?
« Reply #21 on: March 22, 2017, 11:04:15 pm »
I can't speak for Pat but I did a little research on epoxies. I've used two-ton epoxy (30 min epoxy) and it works real well. It should hold at full strength up to 200 and it doesn't require a hot box, but its a little more expensive although readily available. There's other options like T-88 which may be cheaper. Anything made for boats like G-flex should also be good. But again I havenn't used them. Things like Weldwood, Unibond, Smooth On, Resincole are all similar and with good gap filling properties. I made a post about glues that generated good discusion that you can check out. Here's the link http://www.primitivearcher.com/smf/index.php/topic,59138.msg820090.html#msg820090.

What brand? I use Devcon for splicing, but tb3 for limbs.
Debating is an intellectual exchange of differing views...with no winners.

Offline gfugal

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Re: Sizing?
« Reply #22 on: March 23, 2017, 05:51:07 am »
Yes i believe the Two-Ton epoxy is devcon. T-88, Gel magic, and G2 are System Three, and G-flex and 610 are West. Titebond is its own brand.

Hamish i'm not so sure why flexability is bad in a glue. If the glue was glass like then i would imagine it wouldn't handle the bending of a bow. Two-Ton is really bendable i could almost flex it in on its self, however it is hard to the touch, not rubbery. When it did eventually break it broke cleanly. I used it for a handle and didn't have problems. Has other poeple had problems with Two-Ton? I think that if your not careful with the fades and have the handle bend it would snap of the handle with any glue.

If you can get the fits good enough titebond should work for pretty much anything. I believe it has a stronger bond strength then even two-ton. But if it isn't a near perfect fit you'll have risk of failure. Titebond doesn't shrink much (not like hide glue) but it is liquid based and dries rather than cures (thats why you can't wrapp it with a nonbreathable wrap like plastic, air needs to get in there inorder for it to evaporate and dry). If it dries to harden that means its evaporating and thus loosing some volume. So yes it shrinks very slightly but does not sretch or pull things together like hide glue will. Titebond can fill some small gapes but due to its more liquid like state vs gel like epoxies and its drying nature it is not truely "gap filling". Their own specifications state this. But agian, like i was saying if you can get the fit good enough with very small if any gaps it doesn't need to be gap filling and should hold together better than prety much anything.
Greg,
No risk, no gain. Expand the mold and try new things.

Offline BowEd

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Re: Sizing?
« Reply #23 on: March 23, 2017, 06:38:41 am »
Guess I feel fortunate here watching 2 fellas here that make bows.Both use smooth on.I do it their way which is according to the directions and hav'nt had any failures.
« Last Edit: March 23, 2017, 07:41:17 am by Beadman »
Beadman
You got to stand for something or you'll fall for anything.
Ed

Offline willie

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Re: Sizing?
« Reply #24 on: March 23, 2017, 09:05:02 am »
I added a post, with some possibly pertinent thoughts, to the other thread that greg referred to earlier.

http://www.primitivearcher.com/smf/index.php/topic,59138.0.html