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I saw a jig, I think it was by Mr. Collings but not sure. for the glueing up of plates. it used red clamps and two white boards with cauls etc. and I cannot find the pic.

I bought the parts now no picture to build it by


Thanks, Sanford

What kind of plates? Other then archtop all that is needed is binding tape or Scotch 233+ green tape.

Masking tape. See http://www.wellsguitars.com/Articles/Joining/index.html.

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Sylvan
http://www.wellsguitars.com

Sanford, you're getting advice from guys I have a huge respect for, but I feel I should point out that they are very experienced, and so tape clamping works for them. Titebond is calling for 150 psi, more or less, clamping pressure, and that is way beyond paper tape. If your joint is in every respect perfect, ie: freshly knife cut, zero light leakage with modest hand pressure, well-seasoned wood, temperature-controlled shop, 40 - 50% humidity, thin and even glue spread, then you might try tape clamping, but I wouldn't.

Dan

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Dan
http://www.acme-archtops.com

I'm not nearly as experienced as Chris or Sylvan, but I've used binding tape and it worked well for me. I would be shooting for a tight fit with no light leakage regardless of the clamping method employed.

I use something probably similar to what you're building: it's an acrylic plate underneath the top with a thin slot in the center so the joint has some airflow underneath it. That's slotted so I can lay the top on it and tighten three cabinet or pipe clamps on the top. I clamp a couple aluminum bars across the top to stop it from lifting up, apply adhesive, and then clamp the hell out of the pieces until the edges of the spruce start to collapse and crinkle under the pressure.

Regardless of method, as someone said above, your joint prep is more important. You can rub a perfect joint to a pretty good glue joint, and you can end up with a bad glueline in a hydraulic press if your joint sucked

Maybe I'm at a whole new level of anal with the machinist thing, but it's the only way I've found that creates the truly invisible glue line (that's right, get your loupes out!). A stack of nice white lutz tops died in the joint prep/glue type/clamping pressure research (had to snap 'em all to make sure the joints were wood breakage)!

Fun fact: CA was one of the top centenders, and was way ahead of titebond for 'can't see it' factor.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I use something similar to what Bob describes. My jig was inspired by John Mayes. The pic happens to show a back but tops are done similarly. I use HHG but have also used LMI white on occasion.

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JJ
Napa, CA
http://www.DonohueGuitars.com

a properly jointed center seam glued with Titebond requires only positive and constrained butt joint pressure. as long as the plates meat every where (is candled so that no light can pass through the joint when butted up) masking tape can provide enough clamping pressure. The main thing is that the joint is properly fitted is butted up flush and is supported in a way the the the plates will not move out of flush every where. My very first top joint many years ago was glued up with Titebond. I used 3 finishing nails hammered into my work bench to act as stops for the outboard sides of my plates. they were just far enough apart that the center seam net up in a way that the seam flushed up about 1/16" above the work surface (formed a tent). After buttering the joint I pressed the tent down and weighted it. After all these years of building I would estimate that the pressure this method places on the joint is around 20inlbs. Nowhere near 150 lbs. That top is now over a decade old and is just fine.

I now use a three beam screw clamping system very much like JJ's, but all I do is screw the clamps in till the joint is flush. Just like in a column load all added clamping pressure only deforms the plates and is not needed and can cause the plates to split along the grain in the middle of the plates if the force exceeded the cross grain elasticity of the plates.

Michael, ten years and holding could be a testament to accurate joint prep and good (otherwise) construction techniques on your part - I'm thinking of tops, and backs, that are ten, or five, or two years old and are scrap. We all see them - repair folks may chime in now - who knows why they fail? I like to imagine that the people at Titebond know what they're talking about when they say "150 lbs", and I'd guess that the glue manufacturers are ASSUMING clean and proper joint prep.

I belong to the "squeeze it 'till it squeeks" school of panel clamping - the good habit I retained from decades of cabinet building. Dozens of table tops and hundreds of panelled door panels, where the most important thing was perfect jointing, no light leaks. All the clamp pressure went into the glue joint, and not into closing the joint.
I'll allow that the more accurate the joint, then maybe the lighter pressure one can get away with. But what if the glue spread is thick, or the joint is open too long, or the glue was old when you got it, and older since then?

Enough clamp pressure to crush the edges of the spruce is probably just enough; spruce has as good compressive strength parallel to the grain as most other softwoods, and I suspect that clamp-crushing (which is pretty localized) will occur before damage can develope in the body of the panel. Buckling would be the enemy, here, and almost everyone has developed a strategy to limit that.

I'm just sayin' we need to make it clear to the newbies that just because we depart from old practice, that they shouldn't consider the consequences. Actually, WE should apprise them of the consequences, because they just may not know.

Jumpin' Jeepers, here I am on another thread-ending rant, sorry.

Dan

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Dan
http://www.acme-archtops.com

Dan,


Please! I only quoted you in reference to what I had to add to the topic. I never said anything to or claimed you to be dead wrong or any thing like that. I did not rant at you! I did and do disagree the you need 150 lbs of clamping force to make a good joint with Titebond, but that is my experience. I gave a very typical example of plate joinery method applicable to lutherie.

I am always open to others opinions. and you are correct a finly fitted joint is why my joints last. In my opinion unless cleated anything less than a properly candled joint for a top is more than just likely to fail regardless of clamping pressure

Been using this one for lots of years and it has served me quite well

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tim...
http://www.mcknightguitars.com

I like all the info... the jigs shown are more in the direction that I am thinking... maybe a combination of both designs.