Official Luthiers Forum!

I have the LMI Bridge clamp, but I really must say that I'm not very impressed with it.

I'm opting to purchase Stew Mac's bridge clamp to see if it's any better, but I'm also considering using the Go Bar Deck to clamp the bridge while gluing at least this time?

Does anyone see a problem with using the Go-bar deck for gluing the bridge?

_________________
Thanks,
Blain

http://www.ullrichguitar.com

"89.67% of all statistics are made up on the spot."

Would be pretty easy to collapse the top with go bars. I had the stewmac clamp thingamajig but didn't use it. I use three cam clamps via the soundhole. Works great.

Ron

_________________
OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Thanks Ron.

What size cam clamps are you using?

_________________
Thanks,
Blain

http://www.ullrichguitar.com

"89.67% of all statistics are made up on the spot."

Todd, do you use a block or anything inside the box to back the bridge clamps?

_________________
Thanks,
Blain

http://www.ullrichguitar.com

"89.67% of all statistics are made up on the spot."

I think they have a 6" throat. Whatever will fit and reach the bridge.

Ron

_________________
OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

[QUOTE=blain1976] Todd, do you use a block or anything inside the box to back the bridge clamps?[/QUOTE]

When I make the bridge patch I make up a matching caul from MDF and face it with cork. This gets used for clamping the bridge when it gets glued on. I use a combination of cam clamps and Stewmac bridge clamps.

Three or four regular cam clamps do the trick for me. I'm going to try making a 'through the pin holes' version to make alignment a little easier, and obviate the need to make a caul for the inside each time.

[QUOTE=old man] Would be pretty easy to collapse the top with go bars. I had the stewmac clamp thingamajig but didn't use it. I use three cam clamps via the soundhole. Works great.

Ron[/QUOTE]

Ron's right about the potential for collapse.

I've glued on 2 bridges (HHG) using the gobar method. I jacked up the inside such that the bridge plate and x bracing was reinforced prior to applying the gobars. it worked fine and is just another "cat-skinning method"...as long as you take the proper precautions.

I currently use the popular SM bridge caul method with modifications to accommodate locating pins.

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

[QUOTE=old man] Would be pretty easy to collapse the top with go bars. [/QUOTE]
This is true if you just use your regular (fiberglass or stout wood) bars.
If you make some shorter and weaker (wood) go-bars, it is perfectly safe and feasible to use them when gluing the bridge on a steel-string guitar. If you put a bit of a point on the tip of the bar it will seat in the string hole of a pin-style bridge. Two props in holes #2&5 and a couple more on the wings will do it. Gentle pressure is the key- you don't need much pressure if the bridge is properly fitted to the top, so rip up some wood strips and do some experiments.
BTW, it's a good idea to protect the top, no matter what clamping system you use.

This is the method used for steel-string bridges in Sergei deJonge's shop, where I learned it. Sergei uses magnets to 'clamp' the bridges on classicals.

Cheers

John

i've glued many, many bridges using multiple varieties of deep c clamps, originally pony steel clamps, herdim steel clamps, then ibex aluminium clamps with both the s-m and lmi bridge gluig cauls. all can work well in good hands. but after i switched to using vacuum i must say it is so very easy, much quicker and so much less hassle. i would not voluntarily go back to any sort of mechanical clamping.

I haven't on a steel string though I have been toying with the idea, but I always glue the bridge on my lutes with the go-bars. Of course the top hasn't been glued to the shell!



Colin

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I have glued two classical bridges with the system described on the Ostberg website, slightly modified: instead of twine, I simply used books as weights placed on the "yoke". 
First it was about 3 months ago on a friends campfire guitar, which is a classical with steel strings on () and so far it is holding well. The cheap guitar had a maple bridge which popped off some 10y ago because of steel strings.  Some smart repairer used a glue i couldn't identify (white probably a pva), put a lot of it to fill the rips in the spruce. It soon lifted about 3mm but the glue didn't break, it "dilated", elongated. Always hated the looks of that bridge, so I replaced it with a rosewood piece. It was a good learning experience.

So i just used it again on my second build, and it worked very nicely again. Trick is, as John said, to have a perfect fit.

The top caves in a little but rebounds without problems once the weight is lifted.

_________________
Build log

alex, that is one method i haven't seen before! just another of those oft abused cats!

i built my own version of the stewmac bridge clamp. i built it out of scrap (ash i think) and threaded in a 1/4"-20 thread insert above each wing to accept the 1/4" bolts. i only use one big F clamp for pressure in the center. the clamp bears on a cork lined caul against the bridge plate. it's a really heavy clamp but its weight is fully carried by wooded blocks resting inside the guitar. there again i've got cork on the bottom wooden block and glued it up with cork so it rests on either side of the back seam reinforcing strip.
so far i've done six bridges this way and it's worked great. cost about a buck for each of the bolts with the fancy plastic knobs. had everything else in the shop.
phil

Ostberg is showing 3 methods.  The regular clamps in the hole (which I'd use too if i'd have them), the one above, and the screaming cat below.

I guess that depending on one's guts power, a bridge can be glued by simply pressing it with the bare hands. Not sure would work with PVA, though.

_________________
Build log

Hesh, classicals do have a dome right under the bridge, usually about 3mm deflection measuring from the waist level, or about 1mm bridge scoop.  20-25' ?

The scoop is made by sanding on the top as well.

If the no-caul method is adding stress, I guess that is OK because added stress is good in a classical, makes it a tad stiffer.

I read some builders do not bother adding a dome, it will be created later by the string pull anyway.  Or make the top dead flat and only scoop the bridge. 

I've seen a TV doc about a spanish builder growing into a small factory. He was demonstrating the process by glueing fan braces to the top dead flat on a table. 

On the other hand, ostberg, the builder who made the above pics, puts a huge doming on those tops.  4.5mm ! 15' ?  Maybe tighter !

_________________
Build log

    Even if the pressure of the go bars isn;t sufficient to actually collapse
the top while attempting to glue that bridge down, it will cause the top to
flex significantly under the pressure.

    The bridge will most likely stay straight under the go bars, but will act
as a ram to push down on the top.

    The time that you've taken...or should have taken....to fit the bridge to
the radius of the top will have been wasted with this method.

   You really need to clamp the bridge to the top either with clamps and a
caul applying pressure from the bridge down and the bridge plate up
toward it or by pulling the top up int the bridge using a vacuum clamp.
These will create the necessary clapming action while not allowing for or
creating distortion of the surfaces that have been carefully fitted to one
another.

   I'd advise against the go bar idea on a steel string guitar.

Regards,
Kevin Gallagher/Omega Guitars

Old curmudgeon time...

Kevin, I'm with you all the way on this...

What I'm seeing here are methods of bridge clamping that are so bizarre to me as to defy belief. Go bars need to push against something that simply cannot move or flex unless you're clamping braces into a top you want to dome. Strapping levers and wedges to the top is way whacky.

You simply cannot get enough clamping pressure these ways without destroying the top unless you put all kinds of cauls and jacks inside in which case the go bar deck or a guitar in bondage is going to take more time and be more cumbersome than simply doing it the old fashioned way...with deep throat clamps and an internal caul.

I either use Klemmsias or five of the bent steel deep throat clamps from StewMac.   

Thanks for all of the advice.

I went and got some Cam clamps and now have the bridge glued on.

_________________
Thanks,
Blain

http://www.ullrichguitar.com

"89.67% of all statistics are made up on the spot."