Primitive Archer
Main Discussion Area => Bows => Topic started by: bushboy on March 19, 2017, 05:25:22 pm
-
Howdy!after many failures through the years I'm about ready to try some lam bow again.i have titebond 3 and seem to always stave my glue joints mostly because I hate gaps in my glue ups with a passion!was wonder if sizing might help?for etc putting a thin layer on both pieces and allow to dry prior to glue up?thx's bush!
-
Just use epoxy and eliminate the variables.
-
Yes pat,but I hate the smell of that stuff and Uber messy!question not answered though.
-
Yes. Sizing both pieces helps, but I still greatly prefer Smooth On for most applications... properly prepared of course. Starved glue joints and failures are virtually non-existent then.
-
Another benefit that I exploited today on two different bows is the ability to heat and correct alignment on epoxy glued bows... multiple times if necessary. These were bamboo backed trilams of considerable d/r. I won't quit until they're as good as I can make em.
-
Bushboy, What type were you using? Many of them don't seem to smell much, at least to me.
You'll get varying opinions on whether TB likes to bond to a cured layer. It creeps though so I have no use for it.
-
Good points pat and dances thanks!
-
Sizing will not help bad glue joints with TB glues. It is a good idea to do it, but you also need well fitted joints
-
I used unibond just yesterday to glue some bamboo to some ipe, it has very little smell, and is quite tolerable. I bought it by the gallon this time around, I love the stuff.
-
Sizing with TB3 is not recommended. All you would be doing is sticking glue onto glue, not glue to wood. =Weaker joint. Sizing is really only useful on end grain which can suck glue into the fibres and leave a glue starved joint. Not the type of joint that you use when gluing laminations, its all long grain to long grain. Sizing is also useful with a glue like hide glue which can be reactivated with heat or moisture.
With TB3 prep the surfaces, brush the glue on. By the time you are ready to put the pieces together you can check see if you need to brush on more, recoat if necessary then clamp.
-
Try Weldwood Plastic Resin. It is mixed with water and has good gap filing properties. I found it to be similar to Urac. You can get it at ACE Hardware or other places that carry Weldwood products...and it's pretty cheap.
-
Prepare your lams properly, do dry runs to see if there are any gaps. No need to 'size' with TB3, Titebond don't recommend it so don't do it! Simple!
Clamping should be firm but not overly tight.
I've made a few hundred laminated elbs with TB3 in the past and never had one single issue with it. If you follow what the manufacture says for surface prep you will have no problems too.
Good luck :)
Depending on what sort of bow you are making and tools you have I would highly recommend getting the lams as good as you can then find yourself a local cabinet makers shop and ask them to run the lams through their drum sander. It will only take a few minutes and the mating surfaces will be perfect. Making lam bows is like making a house of cards....the foundations are vitally important....if your lams are badly prepared it may all come crashing down!
-
Are you using rubber strips for clamping?
-
dc.yes.
-
pat what epoxy do you use and where do you get it?thxs
-
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.
-
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?
-
Yes,there's one in winnipeg thank's!
-
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.
-
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?
-
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.
-
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.
-
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.
-
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.
-
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