Primitive Archer
Main Discussion Area => Bows => Topic started by: arachnid on October 13, 2016, 08:10:10 am
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Hi.
I`m working on a white oak backed ipe takedown and I`ve made the mistake of not using
an inner tube when I glued it up. I used only spring clamps- bad idea. Seems like all the pressure
was on the center and non on the sides.
(https://scontent.fhfa2-1.fna.fbcdn.net/v/t1.0-9/14702275_1119758141447242_5400292068170105170_n.jpg?oh=27303cdc8c8f0bd73916cf1ebd54197f&oe=589A5B60)
and this is the glue line I got (I used Elmer`s carpenters glue) :-\ :-\ :-\:
(https://scontent.fhfa2-1.fna.fbcdn.net/v/t1.0-9/14729202_1119758148113908_2451756478090073329_n.jpg?oh=193a86adfe04b8978d56847a116f580b&oe=58ABCC8C)
There are small gaps all along the limb, from both sides.
Is there anything that can be done to fix it?
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Fill the gaps with super glue. I had the same thing happen years ago and that fixed the one I was working on.
Second option is to remove the back, clean up both glue surfaces and re-glue it. The TB glue will release at 150 degs. Start at one end, heat an area and use a chisel or screwdriver and get between the layers separating them then work down the to the handle, heating as you go and start on the other end doing the same
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What type of super glue did you use Pat? Liqued or gel?
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That sucks. For the next time, you can use spring clamps, just place 2 clamps at each location, one on either side of the bow, with both pressing on a spot closer to the edge than in the center. I also make the lower lamination a little wider than the upper, and when the clamps press, you can see the ooze out all along the. edge. The puddles at the edges that sit on the wider lower lamination fill in those gaps and then you sand back to the line after glue has dried. Good luck. Russ
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Super glue and PVA glues don't like each other
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I don't like clamps for that type of stuff and I think inner tubes are a pain. I've had the best results wrapping it or tying with cheap cotton twine. Its soft enough to not bite into the wood and provides really precise pressure. Not worth it to use that cheap glue, spend a few bucks and get Titebond. Better luck...
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Marc, I did this with the super glue a couple of times years ago with no problem. Once I found out about delaminating with heat that is the way I went.
Arcahnid, I use cheap super glue. I've tried different brands and most work just fine. Gorilla super glue is crap as far as I am concerned. I've bought it a few times and in every occasion the glue solidified before I used it up, in a few of those cases before I removed it from the original package. Lock-tite seems to work well though.
I have found that bicycle inner tubes work best for me for backing glue ups. I get the tubes from bicycle shops for free, cut the valve section out and cut the tube in half lengthwise with a band or two wrapped around each limb. Once wrapped you can put it in the form and clamp it in place. I usually add spring or screw clamps at the fades and at the tips for extra support. I don't think you can wrap the tubes too tight to cause a dry glue line.
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A bit of first hand knowledge. Don't try and rub the glue into the line with bare fingers. Bamboo slivers hurt, and they really smart when they get super glued into your finger!
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The unknown is the part that will get you. It may look like the edges needs filled. But how do you know there isn't a void across the back? Id scrap it and start over. But what do I know :)
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Inner tube wrap and smooth on will fix your worries next time.TT3 takes smooth exact fitting surfaces for a good bond.It sets up rather quickly too.Smooth on takes roughened up surfaces of at least 36 grit paper[what I use].It gives you more time to adjust things.Like 2 hours but I would get it wrapped or clamped properly in 1 hour if I were you.Then onto your form.A bit more expensive than elmers but you'll get a proper long term bond then though too.
One other thing about smooth on is if you warm the wood and smooth on before sizing I think it's a better bond.
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OOOh.... one thing if you use the innertube wrap method on 2" wide bows I'd lay a 5/16" rope down the center of the limbs and wrap around that too. Putting good pressure on the center of those wide limbs then too. instead of mostly on the edges.
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Thanks for all tge great tips. But, unfortunately, I can't get titebond nor smooth-on (I actually ordered smooth on from Bearpaw Germany through an archery club here, but It'll take some time 'till the shipment will be underway). So, Elmer's is what I have (and it's a good glue. Never failed me. It's just my mistake of not puting enough pressure).
I think I'll try to delaminate it. Just neet to be careful, last time I did it I ripped the backing to pieces.
Does anyone know this method for dissolving glue? It's said that using a towel soaked in viniger should dissolve the glue.
http://www.doityourself.com/stry/building-a-temporary-support-while-your-wood-glue-dries
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I agree with pearl and beadman, smooth on is cheap in the long run as it doesn't take much for a glue up, has plenty of work time even out here when it's110 or up. Like patb said use a heat gun and a stout putty knife and take it apart clean it up and get a redo. I also like to prebend recurves before glue up
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Contact the Elmer's tech support and ask them about degrading the glue with heat. That's how I found out about TB glue.
Another option for glue is Weldwood Plastic Resin. It is a powder that is activated with water. It is cheap and the first time I heard of it was from a PA member from Italy(Alby for those that remember him). Plastic Resin is very similar to Urac or Unibond. It is also a urea type glue.
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Marc, I did this with the super glue a couple of times years ago with no problem. Once I found out about delaminating with heat that is the way I went.
What superglue does Pat is that it works on PVA glues by softening them. The glue up might hold together after but it is weaker
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have you checked with any local suppliers that sell glue for boat building or marine use ...epoxies or urea types?
some sort of way to spread the load under the clamps is helpful, and if you use string, try to find nylon string in a diameter that gives a little stretch.
have you seen yumi construction methods that use string (maybe non stretch is better here) and narrow wedges?
I see that you have just bought some new clamps though, maybe if you do one limb at a time?
many good tips on this thread.
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A while ago I started researching about building FG lam bows (yah yah, I knows... But I want to try it...). I contacted the company that distributes Smooth on here in Israel, but they stopped working with it. Instead they offered me a 2 part epoxy called 'Biresin CR80' manufactured by a german company called Sika. I asked on Tradgang but no one knew it. Does anyone heard of it? Can it be used for bow building? I've tried to read the technical sheet but I'm no technician, I didn't understand. I'll be glad to use it if it's suitable, I can get it pretty easily.
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You can get West epoxy in a marine store in Tel Aviv.
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I have used a product(not for bows) called Sikaflex. Incredible stuff. If their epoxy is anywhere near the quality of this stuff I would use it in a minute. I am also of the opinion that any epoxy made by a reputable manufacturer will work for bows. I use West Systems 105/205 which is made for laminating fiberglass and it works great.
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I just checked that marin store`s wed site. They seem to have West System 105&205 epoxy. I need to give them a call to check out th price and delivary. If it`s good for making bows (wood bows and FG laminated bows) and I can get it in a good price, it might make this glue up failure worth it.
I always thought only smooth on is good for bows because it stays flexible after curing.
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West 105/205 is a 5:1 mix. West offers a set of pumps that dispenses the right amount but the minimum(1 pump of each) is about an ounce. This is about right for laminating a bow but for gluing a handle on or patches you want less. I went down to the veterinarian's office and got two small hypodermic syringes, just the ones for dispensing oral medicines. I routinely mix 1/2 cc of hardener and 2 1/2 cc of resin for these small jobs and have never had a problem with it not curing. I leave the syringes in a block so they are ready to use.
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I just checked that marin store`s wed site. They seem to have West System 105&205 epoxy. I need to give them a call to check out th price and delivary. If it`s good for making bows (wood bows and FG laminated bows) and I can get it in a good price, it might make this glue up failure worth it.
I always thought only smooth on is good for bows because it stays flexible after curing.
Not at all. Glue can be relatively brittle and still handle being an internal glue line. Too flexible and you get creep.
Remember that pretty much anything is flexible when it is as thin as a good glue line.
Check and see if the have G flex or 610. They are thicker and won't be as prone to running out of the joint. You can buy thickening agents for the 105 stuff.
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I just checked that marin store`s wed site. They seem to have West System 105&205 epoxy. I need to give them a call to check out th price and delivary. If it`s good for making bows (wood bows and FG laminated bows) and I can get it in a good price, it might make this glue up failure worth it.
I always thought only smooth on is good for bows because it stays flexible after curing.
Not at all. Glue can be relatively brittle and still handle being an internal glue line. Too flexible and you get creep.
Remember that pretty much anything is flexible when it is as thin as a good glue line.
Check and see if the have G flex or 610. They are thicker and won't be as prone to running out of the joint. You can buy thickening agents for the 105 stuff.
Wait a minute, I`m comfused... Is West System epoxy good for bows or not? Is it too thin?
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It's fine but generally pure bonding epoxy is thicker. Thinner stuff can make it easier to starve the joint. G Flex is thicker and 610 is even thicker still.
The 105 just requires a bit of care or additives which West provides in various forms.
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I use an additive called Cab-O-Sil. The people that sell West stuff will have it. No matter what you use you should cover the back of the bow with masking tape. I also wrap it with plastic wrap before I put the inner tube wrap on. Epoxy will glue the tube to your bow. It comes off but then you can't re-use the tube strips. Oh, I cut my tube strips 1/2" wide and make 2 or 3 passes. I've done 3 boo backed yew bows and numerous patches. I've been about 95% happy with the joints. The 5% was my screw-ups :-[
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All you needed to do with your original glue-up was use a pressure strip to even out the pressure.
Just about any of these glues will work. People have their own favourites.
The best advice I can offer is no matter what glue you use get the data sheet with it when you buy. Follow the preparation steps to the letter.
Thin lams really need a form.
With the gle-up you have done. Use heat to release both sides. Clean them both back up with a drum sander. Make a 1/16th thick lam to take up the reduction in thickness you'll have after cleaning them up. Make a basic form. figure out your glue and how best to use it. Then use a pressure strip regardless of if you use clamps or inner tubes for clamping.
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I read somewhere that water based(like PVA) glues can cause thin pieces(like backing) to cup. If the edges curled up on yours maybe that was the issue. Clamps won't help in this case because they don't all reach the edge. Rubber tubes hold the edges down, sometimes at the expense of the middle, so we use the pressure strip down the middle. If you put the backing on the other way, so the edges curl down, you still need the pressure strip. Epoxy doesn't cause cupping :D
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The water in the PVA gets absorbed and allows the wood to swell unevenly.