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Gorilla glue fast cure experience?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=20398		 Page 1 of 1
Author:  Andy Birko [ Thu Jan 08, 2009 5:48 pm ]
Post subject:  Gorilla glue fast cure experience?
Anyone ever use the Gorilla glue fast cure formula?

I'm attracted to it because there's a couple of joints in the bandura that I absolutely don't ever want to come apart ever ever ever. I've used regular gorilla glue in the past but it usually leaves a glue line. The fast cure formula is clear and claims to cure white which would be perfect.

Anyone know if there is a strength sacrifice with this stuff?
Author:  Michael Dale Payne [ Thu Jan 08, 2009 5:52 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
I have used the original poly formula and dont like it because of the bubbling and expansion. I would expect a hot cure (fast cure to do the same and maybe more.
Author:  Dave Fifield [ Thu Jan 08, 2009 6:24 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
It did very poorly for joint strength in the Fine Woodworking Magazine tests, if I recall correctly.
Personally, I hate the stuff....nasty sticky messy foaming smelly etc....
What's wrong with LMI's Instrument Maker's Glue? It takes quite a bit of heat to make it move in my experience.

Dave F.
Author:  gozierdt [ Thu Jan 08, 2009 7:20 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
It didn't do well in the Fine Woodworking test, is poisonous to dogs and pets, stains
skin black, terrible stuff in my opinion. It's been sold by several manufacturers as
"gap-filling" because it foams, but several tests have shown very poor gap-filling
capabilities. I'd use epoxy every time over it.
Author:  Andy Birko [ Thu Jan 08, 2009 7:25 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
Maybe nothing's wrong with it. It could be a mental thing. These joints are in a peg block (where the tuning pins go) and in one other spot where in a perfect world there would be no joint at all. Similar to but not exactly a built up heel on a guitar in that you never want the joint to come apart.

Something in my brain makes me think that poly glue is Permanent. Perhaps I'm not approaching it right.

No matter, I couldn't wait so I opened the bottle for a test run and glued a couple test pieces together. I'll post my results tomorrow.
Author:  sbjguitars [ Thu Jan 08, 2009 9:39 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
Gorilla glue is the worst stuff I have ever had to deal with. I do not trust it's strength. It is messy, and difficult to deal with. With my repair work I have seen so many home repairs with this crap that destroys any chance of a smooth repair. I also spent some time apprenticing with a second generation Classical cabinet maker where we made custom furniture and also restored antiques. People always tryed to repair their funiture with "The Toughest Glue on Earth". I'm sorry if I offend with this statement but this stuff is useless. [headinwall]
Author:  Andy Birko [ Fri Jan 09, 2009 7:58 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
O.k. so I just performed two tests on two test blocks. if you check out here: http://www.asktooltalk.com/questions/fa ... hesive.php

I performed the shear and the cleavage test on two chunks of hard maple plywood, the type I use for pin blocks in my bandura. I.e. the material I'm gluing. The joint failed on the glue line in the shear test (bad) and the plywood glue failed in the cleavage test.

Mind you, I only use this glue for exactly 4 joints in a bandura (see the pics and read the comments):

1) my rims are a 3-ply laminate of roughly three 1/8" thick strips. I use PU glue because of the long open time and the permanent factor.

2) The neck is glued to the rim

3) The neck and rim are glued to a secondary "rim", what I call the poly frame that allows me to make a curve on the back of the instrument. I've also attached is a pic of the cross section I'm talking about.

4) The pin block (there are 60 strings) is glued to the inside of the rim.

These are all joints that should never ever ever ever come apart. If they do, you've got really big problems. All other joints are glued with either HHG or titebond.

Perhaps the PU glue is overkill but for some reason I get some mental reassurance that these joints will never come apart if I use PU glue.

I think that for the laminate there's no problem sticking with the PU glue (if I continue laminating, I'm going to try steam bending a solid 3/8" piece two instruments from now and if that works I'm going to stick with it) but I'm definitely open to suggestions for the other joints. The key is that it's got to work the first time. I've build 3 banduras with PU glue in those joints and so far they've held up (oldest is almost 10 years old :oops: (the :oops: is because it's taken me almost 10 years to build so few instruments but I've got several good excuses).

Thoughts?

edit: p.s. I'm going to put off these glue joints and start working on the top and back until some consensus is built. At this point I'm at minimum thinking that the gorilla glue fast cure is not the way to go because of the shear test failure.
Author:  Andy Birko [ Fri Jan 09, 2009 8:30 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
One more pic that got dropped from the last post for some reason: here's the completed neck/rim/poly frame from the last instrument I completed. The other pics are from the bandura I'm working on right now.
Author:  Rod True [ Fri Jan 09, 2009 9:23 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
Image

That one on the left looks like pure glue failure to me. You can easily see the grain lines on the plywood on both pieces.

But test piece on the right sure tells a different story.
Author:  Andy Birko [ Sat Jan 10, 2009 12:37 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
Rod True wrote:

That one on the left looks like pure glue failure to me. You can easily see the grain lines on the plywood on both pieces.

But test piece on the right sure tells a different story.


Yes, definitely. The one on the left was the shear test (popped it in a vice and squeezed)

I remember from a long time ago that too much water can weaken the joint a lot so I put together a few more test pieces, one completely dry and the other with a very little wiping of water from a damp paper towel. On the test pieces I posted, I sprayed water on the wood with a little spray bottle. While I was at it, I made a couple of test blocks with titebond. I'll break them tomorrow some time.
Author:  Andy Birko [ Sat Jan 10, 2009 1:07 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
Todd Stock wrote:
That said, I can't see any reason for using the stuff on a guitar if you have any other adhesives available...it is neither as strong in minor gaps nor as easy to handle as epoxies, and is generally more expensive.


After thinking about this some, this seems a bit harsh. Wouldn't a good PU glue (I've now read that apparently pro-bond is pretty good) be a good choice for laminating necks? I'd be worried about starving the joint with epoxy. Using AR would be o.k. but might not be if the neck needs to be steamed off. Seems like PU, plastic resin, or UF would be a good choice for laminations in general.
Author:  Andy Birko [ Sun Jan 11, 2009 4:30 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
The latest test results are in:

GG - no water added - could not get shear to fail, plywood failed first
GG - Dampened with a moist paper towel - also could not get shear to fail

Titebond - couldn't get shear or cleavage to fail.

I suspect I used too much water on the first try so may end up using the stuff, I just won't add any water...unless someone has a better idea.
Author:  jmanter [ Sun Jan 11, 2009 8:42 pm ]
Post subject:  Re: Gorilla glue fast cure experience?
why not try smith's all-wood epoxy?
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