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| Question about HHG http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=47112 |
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| Author: | George L [ Thu Jan 21, 2016 12:30 pm ] |
| Post subject: | Question about HHG |
Friends, Over time I've been working HHG into most of my building processes. On the guitar currently underway I used HHG to affix the top plate to the linings. I worked quickly and had everything in place and clamped within :60 seconds. I've worked enough with HHG to tell when I've "beat the clock" and I think the glue up went okay. That was two days ago. Last night I decided to do a little test before moving on to the back plate. I took a thinned putty knife, wetted the blade with some warm water and tried slipping it between the lining and the top plate. I was surprised at how quickly and easily the two pieces came apart. In fact, the entire plate came off in a jiffy, with very little effort required. I've done this same experiment with Titebond and it was much more difficult in comparison. So, I understand that the ease of repair that HHG provides is the benefit, but I'm wondering just how easy this repairability is supposed to be. Should I be able to pop the top plate free in a couple of minutes by simply slipping a wetted blade between the parts? Or has my test revealed a flaw in my usage? This seems almost too good to be true, although I have found removing bridges, steaming neck joints, etc., to be quite easily accomplished when using HHG, so maybe I'm good to go? Curious, |
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| Author: | Glen H [ Thu Jan 21, 2016 12:53 pm ] |
| Post subject: | Re: Question about HHG |
Did you maybe apply too much clamping pressure, starving the joint? |
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| Author: | Hesh [ Thu Jan 21, 2016 1:23 pm ] |
| Post subject: | Re: Question about HHG |
Hey George. I would suspect that the glue was gelling a bit before all the clamps were in place. Typically HHG will not separate when it comes to top and back plates all that easily. Mind you it will separate but if it only took a few minutes and came off very clean I would suspect the glue joint. Mario P. has an excellent YouTube video that he did showing how he uses HHG to install tops and backs. He messes with the viscosity IIRC and also preheats parts and works quickly. The really brilliant thing about Mario's approach is that he takes a natural attribute of the HHG and uses it to his advantage. More specifically he knows that the HHG will start to gel quickly so he lets the "bead" gel on the outside kind of like a NyQuil gel cap with liquid on the inside. When he smashes the plate on with the clamps the outside of the bead having gelled helps keep the glue inside the bead still hot and liquid. Brilliant! Maybe check for Mario's video on YouTube and see if hie approach helps you out? |
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| Author: | George L [ Thu Jan 21, 2016 2:03 pm ] |
| Post subject: | Re: Question about HHG |
Thanks for the replies. Glen - I'm confident the clamping pressure was not too great. Hesh - This is good to know. Yeah, it came apart very easily, which is what gave me pause. I've seen Mario's video and have tried to adopt his approach. Obviously have a bit further to go in that regard!  Hey, Grumpy, we miss you! ![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up")
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| Author: | DennisK [ Thu Jan 21, 2016 5:42 pm ] |
| Post subject: | Re: Question about HHG |
Hesh wrote: Hey George. I would suspect that the glue was gelling a bit before all the clamps were in place. Yep, I use hide glue for almost everything, but had a lot of problems when trying to close the box with it. If you can get it clamped in 60 seconds, then it's probably possible to get a good joint by increasing the room temperature and possibly improving your warming procedure. But it's a lot easier just to use fish glue or Old Brown Glue. |
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| Author: | DanSavage [ Thu Jan 21, 2016 8:47 pm ] |
| Post subject: | Re: Question about HHG |
DennisK wrote: ...Old Brown Glue. +1 OBG. |
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| Author: | George L [ Thu Jan 21, 2016 9:53 pm ] |
| Post subject: | Re: Question about HHG |
Appreciate the replies.
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| Author: | doncaparker [ Fri Jan 22, 2016 12:07 am ] |
| Post subject: | Re: Question about HHG |
When I have closed the box using hot hide glue, I have done what others have suggested, like heating the parts and moving fast, but I also use a lot of glue. Excessive glue, in fact. This allows it to keep its heat longer. If you just spread a thin layer, it gels faster than if you use too much. Having the plate on the bottom and the rim on top makes this work easier than the other way around. |
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| Author: | profchris [ Fri Jan 22, 2016 4:41 am ] |
| Post subject: | Re: Question about HHG |
After you have your clamps in place you can gently heat the top to hand warm, which will liquify any glue that has gelled, then snug up the clamps if you need to. |
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| Author: | Woodie G [ Fri Jan 22, 2016 8:22 am ] |
| Post subject: | Re: Question about HHG |
We warm the rim both before and after with an industrial heat gun. When we have two workers in the shop, one will continue to gently warm the rim while the other handles the glue-up. I've been able to help with five closeouts so far, and all have gone smoothly and with just a few tiny pearls of hide glue as squeeze-out between kerfing and plate. |
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| Author: | WaddyThomson [ Fri Jan 22, 2016 11:52 am ] |
| Post subject: | Re: Question about HHG |
I have a friend, also a guitar builder, who puts the glue on the rims, doesn't rush himself, puts on the back, makes sure of the alignment, then irons the back rim and places the clamps as he goes around the perimeter. He has over 200 guitars out there, and said he's never had a back come loose. Personally I have never tried it. I have used OBG, and my experience was terrible. I never glued a back with it, but my experience told me it never really dries to the hard glassy crispness that HHG does. It may have been the batch, but I left some in a plastic container, and let it dry for over a week. It was still so rubbery, it stretched and could be bent without ever breaking. I'd never use it in a guitar. Like gluing with chewing gum. "Once burned, twice shy!" |
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| Author: | George L [ Fri Jan 22, 2016 12:25 pm ] |
| Post subject: | Re: Question about HHG |
Good tips. Thanks all! |
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