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 Post subject: Why epoxy for CF?
PostPosted: Fri Jul 15, 2011 5:01 pm 
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Brazilian Rosewood
Brazilian Rosewood

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Just wondering,
Why is epoxy the adhesive of choice for CF rods in necks? What is wrong with regular glue or even CA? If the rods are seated in the bottom of their slot and flush with the FB surface, wouldn't wicking in thin CA be sufficient to hold them in place?
Thanks


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 Post subject: Re: Why epoxy for CF?
PostPosted: Fri Jul 15, 2011 5:12 pm 
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Koa
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It's not just a matter of holding them in place.
For the rods to work effectively they have to be fully bonded to the surrounding wood so that they act as one.
You could not guarantee that the thin CA wicked in will reach everywhere and it is no good at gap filling

Use good slowset epoxy not the 5 minute stuff


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 Post subject: Re: Why epoxy for CF?
PostPosted: Fri Jul 15, 2011 6:33 pm 
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Trouble with regular glue is that it doesn't stick. I've tried white and yellow, and it just pops right off. Been meaning to do a test with hide for a long time, but so far haven't remembered any time I had the glue pot warmed up [headinwall] Probably even worse, I'm guessing.

CA would probably stick, and work, provided it's a tight fit. But I have heard it has less shear strength than most glues, so maybe not ideal. I'm with you though, I'd much rather avoid epoxy (and CA) if possible.


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 Post subject: Re: Why epoxy for CF?
PostPosted: Fri Jul 15, 2011 7:28 pm 
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Cocobolo
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DennisK wrote:
[...] Been meaning to do a test with hide for a long time, but so far haven't remembered any time I had the glue pot warmed up [headinwall] Probably even worse, I'm guessing.

Not too long ago I have done a quick test with HHG and fish glue on a CF rod. I accidentally dropped the CF rod on to the floor and the dried hide glue and fish glue on it had splintered right off.


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 Post subject: Re: Why epoxy for CF?
PostPosted: Fri Jul 15, 2011 9:17 pm 
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Koa
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Must remember to sand off the shiny finish on some CF rods, Dragon Plate for example.
I don't know, but CF fibers are probably bonded with epoxy, so it makes sense to use epoxy as an installation glue.
I have flooded it with CA, and regular epoxy, but I happen to like JB Weld, a thick, aluminum-filled epoxy we get in Texas.
Mario says the best bond, with no creep, and gap filling is polyurethane glue, I think he uses Pro-bond.

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 Post subject: Re: Why epoxy for CF?
PostPosted: Sat Jul 16, 2011 1:16 am 
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Brazilian Rosewood
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David Newton wrote:
I don't know, but CF fibers are probably bonded with epoxy, so it makes sense to use epoxy as an installation glue.


Cured epoxy is inert and the addition of new, wet epoxy won't break down a cured epoxy surface...so techincally, there isn't a reason to use epoxy on that count. You'll only ever have a mechanical bond in this situation. However....epoxy is very aggressive and will bond as well or better than anything else. Just make sure you've sanded a good tooth into the rod...and clean it well with acetone or mek before you glue it.

JB would probably work fine but the fillers are not necessary and it would be better to use a more suitable glue.

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 Post subject: Re: Why epoxy for CF?
PostPosted: Sat Jul 16, 2011 6:18 am 
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Koa
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I am way too allergic to epoxy. Has anyone used other resins, such as used for fiberglass and Bondo?


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 Post subject: Re: Why epoxy for CF?
PostPosted: Sat Jul 16, 2011 7:34 am 
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Brazilian Rosewood
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FWIW Stew Mac Site says:

Gluing
You can use Cyanoacrylates (superglue), epoxies, or wood glues.

http://www.stewmac.com/shop/Truss_rods/ ... ns#details

I've used CF rods only twice before and I didn't even glue them in at all. After learning things here on the forum I probably will in the future but I do wonder how necessary it really is with a proper fit and closed in with the fret board.


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 Post subject: Re: Why epoxy for CF?
PostPosted: Sat Jul 16, 2011 8:03 am 
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Brazilian Rosewood
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I've always used med CA. The bars are a very snug fit in the channel. I seal the groove with shellac, cover it with CA and push the rod in and clamp. I've done it on over 40 guitars and have not had any issues except some leaking of CA into the pores before I started sealing the channel. Thin CA will definitely leak through the pores.

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 Post subject: Re: Why epoxy for CF?
PostPosted: Sat Jul 16, 2011 9:25 am 
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Koa
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If no glue is used, shimming the ends of the rod very tightly in the slot would be important, along with a tight top and bottom fit.
But any glue would be better than none.
If you don't live with epoxy, and who can blame you, find something that works for you.

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