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[QUOTE=Howard Klepper] Vacuum bridge clamping strikes me as an example of thinking that higher tech must be better.
...
Plus the vacuum will tend to pull the glue out of the joint.
...
Why give up your margin of safety unnecessarily, when it is so easy to clamp a bridge in the traditional way?[/QUOTE]

I think it's an example of people considering the forces at work and choosing the simplest solution. On a properly fitted glue joint with glue properly spread on both mating surfaces, the goal of the clamp is to push the mating parts together while evacuating ALL excess glue except that which is required to coat the surfaces. The strongest glue joint is a chemical bond, and that requires the thinnest glue line possible.

Clamping pressure accounts for errors within the parameters above. Too much glue in the joint? More clamping pressure to evacuate it. Poor fit on the joint? More clamping pressure to force the parts together.

I agree that a margin of error is lost, but the margin in this case is accounting for sloppy work, not the requirements of a good bond on a properly prepared joint.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I don't know how else you would glue a bridge on if you don't have a sound hole or its too small.  I've used a whole body clamp, but I don't like putting clamping pressure on the body. Seems like the vacuum clamp is an ideal solution.

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A higher purpose for wood.
Rich Smith
Issaquah, WA

Yep, I would also be keen.
Dominic

OK, so at 11 by my count right now:

Filippo
Ricardo
John Aber
Rick H - 2
Jon Kendall
Joe V
Bruce H
Greg H
Rod T
Gary C

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Though I appreciate the convenience of vacuum clamping, I have always been aware that the clamping pressure is well below recommended values.
Another concern is that water boils at room temperature under vacuum. I assume that water based glues do the same...
In theory, vac clamping seems like a bad idea, but when I researched the method I found that many folks were using it with great success. I first used it on my flat top bouzoukis... none of my clamps were long enough to reach the bridge through the small soundhole.
I have had two failures but I attribute them to using insufficient glue in the joint. I was using Titebond at the time.
I've vacuum clamped six bridges since I switched to hot hide glue last spring. No failures yet, but I am much more careful with fitting & surface prep that I used to be.
I guess time will tell if I have to go back to messing with mechanical clamps... I sure hope not.

OK, I'll be PMing all of you with payment info today.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

OK, I'll be PMing all of you with payment info today. The clamps will be going out once payment and materials land here!

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Cool, so will these be in our hands by Dec 24th Bob? I'll have to wrap it and put it under the tree with my name on it

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

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Im in 3/8" hose

Dang it!!!!!! I have to back out they are not wide enough for my bridges

[quote=MichaelP]Dang it!!!!!! I have to back out they are not wide enough for my bridges[/quote]

[quote=Bob Garrish]The clamps are 3.5"x8.25" INSIDE!!![/quote]

How big are your Bridges Michael? These are inside measurements.

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My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

forgot to put that in the post above.

_________________
My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I miss understood There are 2 sizes

3.5"x8.25" inside and 2.5"x5.25" inside

I am in for the 3.5 x 8.25 inside

[QUOTE=MichaelP] I miss understood There are 2 sizes

3.5"x8.25" inside and 2.5"x5.25" inside

I am in for the 3.5 x 8.25 inside [/QUOTE]

You had me a little shocked there for a second. They didn't seem that big when I made them

Since I like you, you're on the list, too. And because I haven't ordered the materials yet. Now the acrylic's ordered so the list is closed for this set.

My bandsaw is back up this week if I'm to believe the Laguna guys, so there are some more stocking stuffers coming up as soon as I can slice up the blanks (pyramid bridges in all flavours)

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services