Primitive Archer
Main Discussion Area => Bows => Topic started by: Knoll on February 04, 2015, 11:20:22 pm
-
Here's the clamping setup.
(http://i884.photobucket.com/albums/ac48/knolltop314/100_2838_1.jpg)
Here's the result.
(http://i884.photobucket.com/albums/ac48/knolltop314/100_2843.jpg)
(http://i884.photobucket.com/albums/ac48/knolltop314/100_2839_1.jpg)
Done a bit of woodworking and these are the worst gluelines I've ever seen! Bow length is 66" and used 20 clamps, including 2 at riser area. So there was about 3" between clamps.
Glue was TB2. Used this in past gluing risers and glue-on recurve tips. Never had anything like this happen.
Limbs are approx 1 3/4" wide. Wooden blocks placed on backing beneath each clamp ... blocks were 'bout 1 1/4" square.
Thought clamps were tight.
Only section of limbs with decent bond was 6-8" length at tips.
Wanna make another effort, but first . . . . . . . Any ideas re likely culprit/culprits?
-
Get some old bike tire inner tubes, clamp and wrap, then clamp to shape
-
Yup tubes are the way to go, just don't wrap them too tight
-
As long-time cyclist, have tubes galore!
-
Clamps also work. Especially as many as you used. Was the glue visibly getting squeezed out along a thin line? I'm guessing that the materials didn't match up, somehow.
-
Also if u wanna use clamps I rip a piece of wood a little narrower than the backing, and cover it with painters tape for a pressure strip
-
I use clamps, too, about 30 of 'em and a 4 foot 1/8" thick aluminum bar for the center. Before glue up, I hold the backer and belly lam together and put it up to my shop light to check for gaps. Have to make sure both surfaces are perfectly flat. I'll either run it through my belt sander again or hand sand with 60 grit down the center of both lams to make certain there are no crowns anywhere.
-
Yeah clamps work, thats what the tubes are i use two clamps per bow
-
.... Before glue up, I hold the backer and belly lam together and put it up to my shop light to check for gaps. Have to make sure both surfaces are perfectly flat. ......
I didn't, but will in future!
-
Would it help to keep the backing strip not quite as wide as what you are gluing it to? Looks like it is just as wide or wider to me.
-
Would it help to keep the backing strip not quite as wide as what you are gluing it to? Looks like it is just as wide or wider to me.
Sure does
-
The moisture in the glue caused the wood to cup. I switched to inner tube wraps with maybe some additional clamping in fade areas if needed.
-
The moisture in the glue caused the wood to cup. I switched to inner tube wraps with maybe some additional clamping in fade areas if needed.
Exactly this, the same thing has happened to me and it ended up being warped lams. Inner tubes are good because the put pressure along the entire back.
-
The backing strip is too thin to clamp directly to it. As mentioned, the moisture from the glue and uneven clamping pressure will cause it to deform. Use a clamping board on top of your backing strip, and use inner tubes to provide even pressure... plus they're WAY cheaper than 30 clamps. I get flat inner tubes from bike shops for free. They throw them away by the hundreds.
-
maybe the glued surfaces where not flat?, but rounded and high in the middle? I cant see what is wrong with clamps, never had a problem with them ( except expense ).....cant see how this could occur if the 2 surfaces to be glued are exactlty flat
-
Thanks fellas. The resources avail on this forum are top notch!
Rasped/sanded the backer away. Process of doing that showed there was bit of a ridge running full length.
Also could see that bond was better at clamp locations, and visibly less good immediately next door. And 20 clamps exhausts my inventory. :(
Second try is now curing.
Made sure core back was flat. Made sure new backing was flat. Laid length of tin on top of backing. Clamped handle area using large surface area clamping blocks with 3 clamps. Used bicycle tubes to tightly wrap from tips to riser.
(http://i884.photobucket.com/albums/ac48/knolltop314/100_2850_1.jpg)
Now the hard part . . . . waiting!
Thanks, again.
-
I use tubes as well, work great and the glue does stick to the rubber. I have used a long caul, cheap wood like pine 1 x 2. full width and full length. I did my very first bow like that and had no issues what so ever with glue lines and it was 5 lams of maple and oak one lam was tapered.
-
The moisture in the glue caused the wood to cup. I switched to inner tube wraps with maybe some additional clamping in fade areas if needed.
Beat me. I switched to always using shims under each clamp OR innertubes.
Some woods, and hickory can be one, tho I didn't see what the backing was on yours. Anyway, the glue side gets wet, the woood swells and "cups" side to side, and the edges lift.
I have a hickory- backed BL recurve sitting in my garage for4 years still, because it shoots so nicely, but the glue lines are so ugly I don't dare give it to anybody.
-
Reflex glue-up seems to have been success. Though was bit disappointed that limbs retained just 1 1/2" of reflex.
Anyway, decided to go for broke. ::)
Found small piece of hickory laying in the shop. Cut it into rectangular 6 x 1 blocks. Glued them onto the tips. After glue cures will rasp/sand them into static glued-on recurve tips.
(http://i884.photobucket.com/albums/ac48/knolltop314/100_2854.jpg)
-
Looking good - way to persevere! Keep us updated.
-
Looking good, for sure. I had an odd thing happen with the elm backed erc I made. Initially it only held half of the reflex I glued in, too. I'd kept it pretty thick at the fades, and as I tillered it at the handle fades, it gained reflex. I haven't made enough Perry reflexed bows to tell if that's common to all of 'em or if it's just from the elasticity of erc. It wound up springing back all the way back to 3 inches. Maybe you'll have some of that spring back with the wood you're using.
-
Pre tiller the belly so its basically floor tillered then glue it up and it will work better
-
I'd also like to add tip overlays ... something else not yet attempted. Have hunk of rosewood. While the "recurve" blocks are now shaped to width profile of limbs, top surface of them are still flat. Is now the time to add overlays? Anything to be aware of re gluing rosewood to hickory?
-
Not sure how well the first set of overlays are going to hold up.
-
Looking good, for sure. I had an odd thing happen with the elm backed erc I made. Initially it only held half of the reflex I glued in, too. I'd kept it pretty thick at the fades, and as I tillered it at the handle fades, it gained reflex. I haven't made enough Perry reflexed bows to tell if that's common to all of 'em or if it's just from the elasticity of erc. It wound up springing back all the way back to 3 inches. Maybe you'll have some of that spring back with the wood you're using.
That's very normal for bows glued up with forced reflex in thicker dimensions.
-
If not sure then it's understandable not to be helpful on 2nd . . . .
-
If not sure then it's understandable not to be helpful on 2nd . . . .
Yes..
-
Also if u wanna use clamps I rip a piece of wood a little narrower than the backing, and cover it with painters tape for a pressure strip
+1
Just get the cheapest, lowest density junk pine eg. soft stuff for bamboo backing as they will bend to the shape of the boo.
Or use inner tubes.
-
Also do two wraps per limb. One going from handle to tip, then tip back to handle. Making sure that the second wrap is opposite to the first - so the twisting forces even themselves out. If you just wrap one way then you can end up with twisted limbs.
-
Not sure how well the first set of overlays are going to hold up.
Why is that pat?
-
Understand logic re wrapping tubes from both directions.
Question . . . with the wood kinda sealed up by rubber tubing, is a PVA adhesive gonna take long time to cure?
-
Much of the drying is the moisture from the glue going into the wood rather than out through the glueline.
-
Not sure how well the first set of overlays are going to hold up.
Why is that pat?
Their length will make it necessary to move the outer limb bend inboard of the point where the overlay meets the limb.
As long as that is addressed then it isn't a problem. It just seems like a risky choice.
-
As long as thickness taper is addressed it's not a problem I've made lots of overlays this way to create a flipped tip
-
Yes, that's what I said.
Since just getting the main part of the bow glued together is a bit of an issue so far lengthy overlays seemed like an additional potential problem.
-
It seems like you were disappointed in the amount of held reflex and reacted by adding the glue on tip overlay recurves to try to make up for it. Since it seems thicker than finished dimensions, it will gain reflex back as you approach your finished tiller. You really don't need more than 1 1/2" to get a good performance boost. With a thicker limb at glue up, you already compressed enough wood on the back.
My favorite way of gluing these up is using narrow blocks of wood that poke out an inch or so on each side, and using rubber bands looped over the ends, and drawn under the limb and twisted over the other side of the block to hook it, then back under the the limb to loop over the far end. Make the blocks narrow, and put them close together. You can add additional rubber bands if you need to. I still use clamps at the handle, but still with the blocks. This will keep the edges from curling.
I never take a chance with glue. I buy fresh glue that hasn't frozen. With the glue you said you used, you have to have everything in place and move fast!
Have fun.
Dan Perry
-
Thanks all. Have lotsa options when begin the next one.
Mr Perry, we don't see many posts by you. So thanks much for chiming in on this one. While I was a surprised glue line didn't hold more reflex, I'd been planning to do the glue-on tip blocks anyway. Curious to see what combined impact would be in finished product.
Pin nocks are now cut and back/belly edges in process of being rounded.
Fun will soon begin!