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View Full Version : Some Thoughts on Making and Using a Tuner Caul Bridge Clamp



sequoia
12-13-2015, 05:19 PM
A while back I realized I could not use standard bridge clamps because there was no room in the thin ukulele I am building. Ken kindly responded with plans on how to make a bridge clamp using tuners and fishing line. I constructed the contraption below.

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Its construction is self-explanatory I assume. Now Ken's clamp is probably made of walnut, perfectly aligned, perfectly square and buffed to a high gloss. I just used some plywood and pine off the kindling pile and it isn't pretty, but it will do the job. Sorry Ken.

Below the bridge location is determined and taped out with 2 layers of masking tape. There is no finish to remove since the location was taped off prior to finishing and is bare wood. The holes are drilled. 1/8 inch holes which are much larger than needed but since this uke is going to have an under-saddle pick-up, I can kill two Terns with one stone and only drill the holes once. The fishing line (actually a nylon uke string) is passed and fished through the sound hole. A tricky little problem by the way and requires a Zen attitude. A lead sinker is attached to a swivel and is used as the stopper and will butt up against the bridge patch. Note the line attached to the other side of the swivel so that the stopper and lines can be retrieved after the bridge is clamped and glued.

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Lines up through the bridge, threaded through the tuners and clamping pressure applied. Masking tape removed with glue squeeze out and bridge is clamped.

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Some thoughts:

- What a Boy-Scout project that was. Took the better part of an afternoon. Fun in a way. At least I got to go through my old fishing tackle.

- One problem: It is hard to get any tactile feedback on how much pressure you are applying when cinching down the caul. No way to really tell and you don't want to break the string. That would be a major bummer. I went by watching for "good squeeze out" and quit applying pressure. I suspect I could have applied a lot more pressure. Rack and pinion tensions can get really strong. I think you could over clamp with one of these things and glue starve the joint.

Anyway, the system certainly works, but it is a lot of work and slow to set up. However, in this rare situation, it is the right tool for the job. Thanks Ken!

Timbuck
12-13-2015, 09:15 PM
Now Ken's clamp is probably made of walnut, perfectly aligned, perfectly square and buffed to a high glossgloss. I just used some plywood and pine off the kindling pile and it isn't pretty, but it will do the job. Sorry Ken.

Actualy ! I never made one of these .. But if I did, it would most likely be made from aluminium, or Delrin, Nice to know it works tho' :cool:

Vespa Bob
12-14-2015, 06:37 AM
I can see that it's a tedious method of clamping a bridge, but sometimes you have to do whatever works. What about using hide glue for the job? According to Robert O'Brien in his video on hide glue, no clamping is necessary
.http://www.lmii.com/tutorial-videos
You may have to scroll down to find the vid. I don't want to hi jack your thread, Sequoia, but if someone would chime in whether they have successfully used hide glue without clamping in this scenario, I for one would consider it over the fishing line/tuner/caul method.

Bob

Beau Hannam Ukuleles
12-14-2015, 06:57 AM
This is also a good method for side crack repair where it is difficult to work- magnets can also work but this is better

Kekani
12-14-2015, 08:37 AM
Vacuum. Done.

As a convenience, Bob is selling his right now, in the shameless forum.

Michael N.
12-14-2015, 09:47 AM
I can see that it's a tedious method of clamping a bridge, but sometimes you have to do whatever works. What about using hide glue for the job? According to Robert O'Brien in his video on hide glue, no clamping is necessary
.http://www.lmii.com/tutorial-videos
You may have to scroll down to find the vid. I don't want to hi jack your thread, Sequoia, but if someone would chime in whether they have successfully used hide glue without clamping in this scenario, I for one would consider it over the fishing line/tuner/caul method.

Bob

I've done it dozens of times. Yet to have a failure. In fact I don't really use a rubbed joint as such. The bridge is just held in position for a few minutes using light finger pressure. Let go, that's it. I read about the technique 10 years ago in one of David van Edwards Lute making courses. He coats the underside of the bridge and then places it in position onto the soundboard. He then removes it, recoats with glue and then finally places it into position, held there for a few minutes. It sounds as though it can't possibly work but believe me it does. Of course you do need well fitting surfaces and a glue that is neither too thin or overly thick.
I don't use this method on thin soundboards that have a lot of 'give'. Those can be easily distorted even by light finger pressure. I'm fairly certain that most small Ukes will be fine for the method though.

Vespa Bob
12-14-2015, 10:57 AM
Thank you, Michael, for your vote of confidence in the use of hide glue and the method of using it. I'll give it a try.

Bob