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Plate joining
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=47574		 Page 1 of 2
Author:  bcombs510 [ Tue Apr 05, 2016 1:24 pm ]
Post subject:  Plate joining
Hello,

I use something similar to this for plate joining. The only difference is I have 3 cams per side and two cross clamps that run perpendicular to the caul that covers the center seam. http://ultimate-guitar-building.com/gui ... nting-jig/

Then on Facebook today I see this: https://thedutchluthier.wordpress.com/2 ... -the-shop/

Now, I'm not at all calling into question this method. I'm just curious how a single rope clamp in the middle and two binder clips are working? My guess is the preparation of the joint has to be perfect, and probably is, but am I worrying about nothing with my 6 cam clamp, 3 caul monstrosity? :)

Thanks!
Brad
Author:  Clinchriver [ Tue Apr 05, 2016 1:28 pm ]
Post subject:  Re: Plate joining
I use 4 aluminum bar clamps, I wonder if he's using a slightly "sprung" joint?
Author:  SteveSmith [ Tue Apr 05, 2016 1:28 pm ]
Post subject:  Re: Plate joining
As you said, perfect joints are the key. I wouldn't be surprised if he joins them with a few thou gap in the center.
Author:  bcombs510 [ Tue Apr 05, 2016 1:36 pm ]
Post subject:  Re: Plate joining
Here is my jig.

Image

Between your two replies I think I get the idea. You intentionally leave a few thousandths gap in the center and the rope clamp pulls it together so the gap is closed and the ends land perfectly. Correct?


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Author:  bcombs510 [ Tue Apr 05, 2016 2:19 pm ]
Post subject:  Re: Plate joining
I found this write up on spring joints. I wonder how many folks use this? The method the author describes for using the jointer to put the gap in seems straight forward enough.

http://www.finewoodworking.com/item/267 ... est-friend

Learn something new every day!
Author:  kencierp [ Tue Apr 05, 2016 2:23 pm ]
Post subject:  Re: Plate joining
Here's our plate joining set up we have two -- simple and fast! I don't use a spring joint, bet there are arguments for and against.

http://kennethmichaelguitars.com/Jointi ... alves.html
Author:  SteveSmith [ Tue Apr 05, 2016 2:32 pm ]
Post subject:  Re: Plate joining
I always try to get the plates joined perfect but if there is a very small gap in the middle (just a few thou), I'm ok with that as that comes together quite easily when I glue them. I would not call that a spring joint though. Not ok at all with any gaps on the ends.
Author:  James Orr [ Tue Apr 05, 2016 3:38 pm ]
Post subject:  Re: Plate joining
I'm not one to invest in many jigs as opposed to making them, but when I saw Robbie O'Brien's ad for LMI's plate joining jig, yes please. I couldn't be happier with it.
Author:  jfmckenna [ Tue Apr 05, 2016 3:47 pm ]
Post subject:  Re: Plate joining
I have used a spring joint in the past but gave up on it as I read further into it and have a better understanding of joining plates. But yeah, he may be using a spring joint in which case that clamping system would work fine.

I have a set up similar to Ken's, easy peasy and takes up no room in the shop.

Image
Author:  DennisK [ Tue Apr 05, 2016 4:23 pm ]
Post subject:  Re: Plate joining
I'm on the side of "get it perfect and you don't need pressure". Rosewoods are so hard that you can't squeeze out any gaps at all with clamping pressure. So you either need to be able to cut a perfect joint, stick to softer back woods like mahogany and use clamping pressure to squeeze gaps shut, or use clamping pressure on the soundboard and inlay a backstrip on the back to cover up a bad joint (this is what I did on my first few).

With a perfect joint, you can stretch a few strips of tape across the show face, plus a long strip up the middle to keep glue off of it.
Attachment:
TopJoining.jpg

Then flip it over and lift if up like a tent.
Attachment:
SoundboardTent.jpg

Squeeze glue in the gap, drop it down, press with your thumbs on either side of the joint to eliminate any "step", stretch 3 strips of tape across the back side, and it's good to go. At least with hot hide glue, it's safe to handle after a couple minutes, so you can set it somewhere else and do the next one :) You can even can peel the long tape off and reuse it, as long as you're careful not to disturb the joint in the process of peeling. It'll dry faster without it, too.
Author:  Hesh [ Tue Apr 05, 2016 5:00 pm ]
Post subject:  Re: Plate joining
I'm with Dennis and use the tape method. I squirreled away a big stash of the Stew-Mac "brown" tape that I like to use for joining plates.

As such Dennis and I don't need no stinkin jig....:)
Author:  SteveSmith [ Tue Apr 05, 2016 5:08 pm ]
Post subject:  Re: Plate joining
I've used the tape method but I'm with James now and I use the LMI jig. I like that I can move it out of the way and it does work quite nicely. It's a convenience for me because the results I got with tape were just fine.
Author:  Clay S. [ Tue Apr 05, 2016 5:54 pm ]
Post subject:  Re: Plate joining
I've used the tape method for years with no failed joints. I do add a spring clamp on either end and use that to hang the plates from a coat hanger in a closet. I will do several at a time and hang them all to dry so air can circulate on both sides of the joint. I don't do sprung joints. I feel the thinness of the plates needs a properly made joint.
Author:  Rod True [ Tue Apr 05, 2016 6:25 pm ]
Post subject:  Re: Plate joining
I made my own spanish tourniquet jig similar to the LMI one. I also like that I can get it out of the way when done...
Author:  Ken McKay [ Tue Apr 05, 2016 7:01 pm ]
Post subject:  Plate joining
I use nails. No really.

On a plywood backer i place the book match.
Along one edge I hammer in a straight edge board.
Along the other edge I place another straight edge board

Hammer nails outside of the free straight edge just skimming the edge.

With a hammer bend the nails in pushing the joint tight

I usually use about 4 or 5 nails




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Author:  bftobin [ Wed Apr 06, 2016 6:48 am ]
Post subject:  Re: Plate joining
Back in the early 70's, Bill Lewis said he saw luthiers in Spain using a single wedge system like the one above and said it appeared to work very well.
but he used a three wedge system himself. Pat Foster uses the three wedge system, and it works well for him.
Another example of how many methods will work.
Brent
Author:  jfmckenna [ Wed Apr 06, 2016 7:26 am ]
Post subject:  Re: Plate joining
I started off with the wedge method in my image above and then started using the tape method and now am back to the wedges. I find the tape more cumbersome and have in fact had the joint slip on me in the past and had to redo it. For it to work perfectly it seems you have to have the same amount of tape pressure on both sides. To each their own and what ever works best I like to just set the plates down and tap in wedges. But as far as clamping pressure no matter what method you use you don't jam the hell out of your wedges or ropes and apply too much pressure. So I don't think roping or wedging methods are about more pressure, unless you are doing it wrong, but rather just a nice evenness of pressure. BTW now that I think of it when I did do the tape measure I used to set it out of the way too and that was kind of nice in a small shop.
Author:  Woodie G [ Wed Apr 06, 2016 8:03 am ]
Post subject:  Re: Plate joining
Tape AND wedge in this shop. Lack of glue line pressure can be an issue with tape and correct across-plate and through-plate alignment can be a problem with wedges, so combining the techniques allows the joint to be blocked open, hot hide glue to be applied to the joint, and rapidly closed to get initial clamping with good alignment. Wedges apply more glue line pressure than than tape is capable of providing, thinning the glue line to invisibility (hint: dog ear the end of the join on one side of the plate - otherwise, the joint can be very hard to find after gluing). The vertical wedging similar to Cumpiano ensures that tops that are already close to final thickness dimension stay in alignment while the glue gels.

We are working on a video tutorial for this approach - I just need to coerce the boss into taking the time to finish shooting so I can edit and produce...there is not enough time in a weekend!
Author:  Arnt Rian [ Wed Apr 06, 2016 9:34 am ]
Post subject:  Re: Plate joining
I use 3 normal glue clamps, with a couple of Klemmensias to keep the plates in line as I apply pressure. No special reason, except I have them, its pretty fast and it works every time.
Author:  truckjohn [ Wed Apr 06, 2016 10:03 am ]
Post subject:  Re: Plate joining
I have seen a lot of guitars with center seam failures...
I try to get my joint as perfect as possible.... I want to stack the deck as much as possible in my favor as I can.

That said - I have seen the majority of those seam failures in the middle rather than on the ends - so it makes me wonder if their procedure allowed springing it in the center.

Thanks
Author:  johnparchem [ Wed Apr 06, 2016 10:21 am ]
Post subject:  Re: Plate joining
I use the LMI rope jig for guitars and tape for ukuleles and book matched head stock veneers. I make the joint as perfect as I can. I might allow a very small gap in the center. I never force the ends to close.
Author:  Woodie G [ Wed Apr 06, 2016 10:53 am ]
Post subject:  Re: Plate joining
Quote:
I have seen a lot of guitars with center seam failures...
I try to get my joint as perfect as possible.... I want to stack the deck as much as possible in my favor as I can.

That said - I have seen the majority of those seam failures in the middle rather than on the ends - so it makes me wonder if their procedure allowed springing it in the center.

Thanks

I am not certain that cracks can easily open at the edges of the top, due to the increased gluing area of the linings and the tail block, or continue through the bridge area due to the bridge plate, so that leaves the center seam away from the edges as the likely failure point.

From what I've seen of this winter's crop of top cracks so far, the most common are from the back of the bridge plate to just shy of the binding and within an inch or so of the centerline. Thus far, only one centerline seam failure, and that is an old, repaired joint on a 70's era HD-28. On centerline glue failures, that we have in our repair records are on 1999-2005 Taylors, which is thought by the boss to be a combination of poor joinery and inadequate RH management in manufacturing. More recent Taylors don't seem to have nearly as many issues with center seams opening, so I have to assume they changed some procedures or had their jointer blades sharpened ;)
Author:  Quine [ Wed Apr 06, 2016 12:02 pm ]
Post subject:  Re: Plate joining
Nice to see there's so many methods for the same task.
I don't use a jig...just a flat mdf board with blocks clamped at the edges of the plates and some wedge shims. Its a bit fussy but it works for me. If I built more than a few per year I would look at making one of those cam setups.
Author:  quentinjazz [ Wed Apr 06, 2016 3:21 pm ]
Post subject:  Re: Plate joining
+1 on stewmac's brown tape for joining!
Image
Author:  Pmaj7 [ Wed Apr 06, 2016 4:08 pm ]
Post subject:  Re: Plate joining
Are you guys using tape stretching it across or just laying it down flat with the halves pressed together tight?

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