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technique for "perfect" joints between backs and sides? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=22338	Page 1 of 1

Author:	Corky Long [ Mon May 11, 2009 11:10 am ]
Post subject:	technique for "perfect" joints between backs and sides?
I'm building number 5 (OOO sized Koa steel string) and am using HHG for this one. I've read about how joints glued with HHG need to be tighter than Titebond, for example - the glue apparently doesn't fill gaps very well. So, this is an opportunity to address a part of building that I haven't done very well, previously - fitting the back to the sides with jigsaw puzzle - like precision. I've struggled, while cutting the braces to length and cutting the kerfing on the sides to accomodate the end of the brace. I've experimented with a couple of techniques - 1) keeping the sides in my mold - which has the advantage of keeping the sides in the exact shape of the desired end product, but the disadvantage of access to the joint - so I can see where to take some wood off, etc. - or 2) taking the sides out of the mold so that I have access, but disadvantage is the sides (side assembly actually, with neck block and tail block and kerfing all in place) lose their shape enough to make a difference. Who's got a technique that works well? What am I doing wrong? Thanks!!

Author:	TonyKarol [ Mon May 11, 2009 11:30 am ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
Using a sanding bowl to contour the sides/linings will pretty much eliminate gaps ...., plus it keeps things consistant as you build a given , and as you build more guitars.

Author:	Chris Paulick [ Mon May 11, 2009 1:18 pm ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
When cutting the lining for the brace ends what I did was to have the brace ends at a consistant dept first. I do this by sanding the brace ends with my OS sander at first before gluing them but there are other ways too but just get them all the same. Then I position the top/back on the ribs after they have been sanded in the radius dish and I go around and trace the edge of the brace ends on the linings and then just take a Dremel with a bit set to the correct dept and notch the linings. If you do it correctly then the Top/back will snap in place and locate itself when gluing it on. Well at least the the top will as the back with ladder braces can move side to side. This is how I did my back the first time I used a gobar deck. I've since made some changes. Like using some clamps to hold the back in place instead of tape. http://www.youtube.com/watch?v=nw8li-D7sU8

Author:	Chris Paulick [ Mon May 11, 2009 1:40 pm ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
And here's part 2 http://www.youtube.com/watch?v=OrBwl2x36nk

Author:	David Newton [ Mon May 11, 2009 4:23 pm ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
First things first.... "perfect" what's that? If you don't use a dish, you could slide the sides up and clear of the mould for access, but still clamp them to the mould with some sort of braces. I make my moulds less deep than the body.

Author:	jordan aceto [ Mon May 11, 2009 5:58 pm ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
I think it is mostly just practice, whatever your method. I like to keep the sides in the mold, 'cause that's what the mold is for, doing it that way means lots of flipping the whole thing over to see how things are fitting, if the top is already glued on then you just have to "use the force". I run the braces right through the sides, where they will later be covered by the binding, that makes them a little bit easier/faster to fit.

Author:	Chris aka Sniggly [ Mon May 11, 2009 6:29 pm ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
I run the braces thru like Jordan does. It takes one of the aggravating issues out of fitting. I wish I had a picture of it...but I use a depth gauge block I made out of some spare Mahogany to check the height of the brace ends. That way I can get them all consistent right out of the gate and not have to play the game of 'take a little..check...take a little...check'. Just make a block and cut out a notch that is 50 thou or 80 thou deep (whatever depth you like)...keeping in mind the width of your widest brace ...and boom...Bob's yer uncle... ..I said boom.... Good luck my man. Chris

Author:	Corky Long [ Tue May 12, 2009 8:50 am ]
Post subject:	Re: technique for "perfect" joints between backs and sides?
Thanks, all - very helpful. Running the braces through the sides - that never occurred to me. Very interesting. I also like the 80 thou template for making the braces uniform height. Thanks!

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