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CA glue for a broken pegbox?


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I've got a Robert Glier (Wurlitzer) violin that has a pegbox broken right through the A peg hole. The break is nice and clean with no missing pieces. I'm thinking about just gluing it with Satellite City "Hot Stuff" Medium CA glue to avoid all labor and troubles that come with making cauls and clamping. I'm thinking all I have to do is apply glue and perhaps activator to one side of the joint, hold it together until it sets, and I've got a near -invisible glue line with no clamping. My pre-made spiral bushings are strong and should prevent any splitting pressure from the A peg. This brand of CA glue is popular among luthiers, but when I tested it yesterday on unprepared surfaces, I didn't get quite the results I expected. I'll probably go back and repeat the test on freshly exposed surfaces, but while I'm waiting on that, I figure maybe it's best to ask for input from others as to what their experience has been with "Hot Stuff" Super T glue.

When I put the spiral bushing in, it should reinforce the glue joint across the break, making the whole assembly stronger than new, and as reversible as practical.

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11 minutes ago, Michael Richwine said:

When I put the spiral bushing in, it should reinforce the glue joint across the break, making the whole assembly stronger than new, and as reversible as practical.

I don't consider any wood glue joint made with cyanoacrylate adhesive to be easily reversible.

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I have no experience with this particular glue.  But it seems to me that the strength of this repair will mostly come from the bushing, not the glue in the crack, and the function of the glue in the crack is mainly to hold the crack together while the bushing is installed.  So I wouldn’t categorically rule out the use of Hot Stuff glue here.

But, as David says, it’s not easily reversible.  So I think Hot Stuff would be OK on cheap instruments but not on expensive ones.  I’m not sure if I consider a Glier cheap or expensive in this context.

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1 hour ago, David Burgess said:

I don't consider any wood glue joint made with cyanoacrylate adhesive to be easily reversible.

The debonder for CA glue is nitroalkane, which is said to be safe for most finished surfaces. Haven't tested it myself; that's why I'm asking for input from others with more experience. I seriously don't know how much different that would be than trying to undo a repair done with hide glue, or why/ when I would want to undo one. A spiral bushing can at least be reamed out and replaced without removing any additional wood, beyond what's required for the initial repair..

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1 hour ago, Brad Dorsey said:

I have no experience with this particular glue.  But it seems to me that the strength of this repair will mostly come from the bushing, not the glue in the crack, and the function of the glue in the crack is mainly to hold the crack together while the bushing is installed.  So I wouldn’t categorically rule out the use of Hot Stuff glue here.

But, as David says, it’s not easily reversible.  So I think Hot Stuff would be OK on cheap instruments but not on expensive ones.  I’m not sure if I consider a Glier cheap or expensive in this context.

Agree that the strength comes in large part from the bushing, but as an old woodworker I like to see all elements contribute. I'm running another test, and doing some more reading.

Looking at auction records, Glier's fiddles don't bring a lot of money. 

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11 minutes ago, Michael Richwine said:

The debonder for CA glue is nitroalkane

I have no experience with that stuff, but one observation is that "debonding" is very different than being able to thoroughly clean the glue from the wood to prepare it for another repair.

On a very inexpensive instrument the repair you describe might be the right way to go to save labor, but I wouldn't otherwise. 

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If I'm interpreting your thinking correctly, you don't want to use hide glue because its hard to clamp without the 2 pieces sliding out of line? Is that right?

One way round this is to install a temporary bushing into one half of the broken peg hole. You have to do some tweaking to get the fit right, but once it's glued in place you can fit the other piece on top, and the bushing locks the 2 pieces in place when the joint is closed without sliding. You just need to make  2 clamping cauls that won't take you more than a few minutes on the bandsaw. When the glue is dry, drill/ream out the temporary bush (if you drill carefully you can remove hardly any original wood). Then do your spiral bushing as usual. 

Maybe I haven't explained this very well, but if you sit with the two broken pieces and an old peg or bushing in your hands, I'm sure you'll see how it would work...

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1 minute ago, Bodacious Cowboy said:

If I'm interpreting your thinking correctly, you don't want to use hide glue because its hard to clamp without the 2 pieces sliding out of line? Is that right?

One way round this is to install a temporary bushing into one half of the broken peg hole. You have to do some tweaking to get the fit right, but once it's in place you can fit the other piece on top, and the bushing locks the 2 pieces in place when the joint is closed without sliding. You just need to make  2 clamping cauls that won't take you more than a few minutes on the bandsaw. When the glue is dry, drill/ream out the temporary bush (if you drill carefully you can remove hardly any original wood). Then do your spiral bushing as usual. 

Maybe I haven't explained this very well, but if you sit with the two broken pieces and an old peg or bushing in your hands, I'm sure you'll see how it would work...

I get it. An old peg (waxed) for alignment and maybe some neoprene foam to line the cauls might save a lot of time. Even with hide glue, and knowing how it contracts, I still like to use a fair amount of clamping pressure to keep the glue line thin.

This is why I ask questions here. So I can think things through before, and not after... When I was in a shop, there were always people with opinions and experience nearby. Working alone, you don't always think of everything.

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28 minutes ago, Mark Norfleet said:

I have no experience with that stuff, but one observation is that "debonding" is very different than being able to thoroughly clean the glue from the wood to prepare it for another repair.

100% agree.  Removing CA glue remnants from cracks is an awful experience. 

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I can't find it right now, but somewhere I have a photo of a repair I did of an A crack on a cheap violin. I clamped it with a large spring clamp (orange pads, new!) which did sneak up in there nicely, but wasn't strong enough. Then I put a regular c-clamp on the spring clamp, which closed it up fine. It worked perfectly and didn't dent anything. I think I'd only use that nice soft new orange padding (Jorgensen spring clamp), not cardboard or something hard--that would be asking for dents. There wasn't a problem of sliding around with that particular crack.

I'm with the group that says use hide glue, but with my clamping method you shouldn't be crying too much.

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I'll give that a try, dry clamping and all. I've gotten along with just hide glue for a very long time, so might as well stick with what I know. Just got lazy thinking CA glue might save me some time and energy, but a little thought and imagination, or a few questions are worth while. Thanks, all!

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On 5/28/2022 at 10:03 PM, Jerry Lynn said:

100% agree.  Removing CA glue remnants from cracks is an awful experience. 

You have to try submerging in pure acetone :-) That works.

After reading the OP, I would suggest just using high gram strength hide glue in full strength (no extra water) . That should grab in a minute or so. I'd hold it for two minutes and put it aside to dry in a position that will not create undue stress on the crack.

I've used liters of CA but I would not use it here unless it was some junk violin and wanted to do quick&dirty job to make it playable in 15 minutes.

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I haven't used CA glue much at all, and none on violins. That's why I asked for opinions. I will report that on the test joints I made with fresh planed surfaces, the glue failed through the glue line, which is something I don't find acceptable.

I picked up a couple of Pony spring clamps this morning and will try Michael D's suggestion tomorrow AM. Failing that, will make cauls and do the conventional approach.

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2 hours ago, Michael Richwine said:

I picked up a couple of Pony spring clamps this morning and will try Michael D's suggestion tomorrow AM. Failing that, will make cauls and do the conventional approach.

Another clamping option for that area is to use a chinrest clamp.  I’ve used a conventional one that spans both sides, but it occurs to me that an inexpensive titanium Hill style single clamp could be quite useful with a simple caul for the back of the scroll.

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Oh, oh. I should have said the large Pony clamps, not the 1 inch common ones. And the head I did it on was still intact--I'm not getting if yours is broken entirely off? But it still might work and you'll find out right away. Anyway, IMO there's no such thing as having too many spring clamps.

I use the debonder to get super glue off my clothes. It turns it into sort of a sloppy putty that you can scrape off, but I don't think it would work in a crack.

Cowboy's idea of a peg for locating is great!

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Fwiw, I would not consider this repair a repair where I would expect or want reversibility, unless of course it fails.

Problem is with these repairs that it's somewhat not up to you if they work or not, all it takes is a moment of frustration with someone fighting the tuning peg to re-blow out the hole, bushed or not, I would suggest hide, not for reversibility as much as if it ever comes back you will be able to try again easy, with CA, thats generally not the case....And that lightning fast set time is generally a good thing, until it's not, CA is a one shot deal and if for any reason there is a little wobble of something not going right with the mating , you're kinda screwed.

If you have not used CA much , I would suggest breaking several piece of small wood to do some practice mating , including some where the piece is still hanging on, split, not cracked in half. this helps give you an idea of what it takes to work it in and your open time, which is pretty nil.

The other factor is clean up and protecting the varnish

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On 5/30/2022 at 9:24 AM, jezzupe said:

Fwiw, I would not consider this repair a repair where I would expect or want reversibility, unless of course it fails.

Problem is with these repairs that it's somewhat not up to you if they work or not, all it takes is a moment of frustration with someone fighting the tuning peg to re-blow out the hole, bushed or not, I would suggest hide, not for reversibility as much as if it ever comes back you will be able to try again easy, with CA, thats generally not the case....And that lightning fast set time is generally a good thing, until it's not, CA is a one shot deal and if for any reason there is a little wobble of something not going right with the mating , you're kinda screwed.

If you have not used CA much , I would suggest breaking several piece of small wood to do some practice mating , including some where the piece is still hanging on, split, not cracked in half. this helps give you an idea of what it takes to work it in and your open time, which is pretty nil.

The other factor is clean up and protecting the varnish

I've long since learned the value of testing and at least minimal research. I did make some test joins, and I didn't like the results. I also like the easy cleanup and reversibility of hide glue when you get down to the nitty gritty.  That, plus Michael D's and Cowboy's clamping suggestions tipped the balance pretty overwhelmingly. The CA glue goes for making quick fixtures and other, non-critical applications. I had been wondering for some time. Now I know better. I've always got hide glue handy, so as long as I keep it fresh, I'll probably stick with it for a few more decades if I last that long.

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