A common method of gluing a bridge on is the use of clamps placed through the soundhole. But for this bit of instrument whimsy built from scraps scavenged from last summer's flood, that technique wouldn't work. So I bodged up a vacuum clamp from junk.
I cut a ring of hobby/craft store 6mm foam, and then stuck some polyethylene foodwrap to it with double-stick woodturner's tape. I cut a bit of screen from a blownout doorscreen to allow air to reach the extraction point. The extraction point is a hypodermic needle inserted through the edge of the foam ring, and that is connected to a vacuum line.
I had previously set the bridge location and intonation using a temporary tailpiece to anchor the strings, and then traced around the location. Then I heated up the HHG, spread it on the bridge and then placed it. I turned on the vacuum pump and held the bridge in place with one hand while laid and pressed the ring in place. The transparent film made it easy to be sure that the bridge was in the correct location.
barebones bridge vacuum clamp
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Bob Hammond
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barebones bridge vacuum clamp
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Jason Rodgers
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Re: barebones bridge vacuum clamp
I'm impressed! The only task I have for my vacuum system is a holding platen for carving solidbodies. The simplicity of this caul really surprises me.
-Ruining perfectly good wood, one day at a time.
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Randy Roberts
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- Location: Omaha, NE (a suburb of Iowa)
Re: barebones bridge vacuum clamp
Nice!
If the rubber hose tends to collapse on you, the vinyl tubing with white reinforcing thread found at mostw any hardware store works well also.
If you have access to needles, then you might also have access to a tuberculin syringe and a three way I.V. valve. Cut the flange off the back of the syringe barrel and the barrel fits perfectly inside the hose. The three way valve puts the vacuum control right at your hands right where you are working so you don't have to mess with reaching for the pump controls while your trying to do all the other stuff.
Seems to be a pretty hefty bridge there?
If the rubber hose tends to collapse on you, the vinyl tubing with white reinforcing thread found at mostw any hardware store works well also.
If you have access to needles, then you might also have access to a tuberculin syringe and a three way I.V. valve. Cut the flange off the back of the syringe barrel and the barrel fits perfectly inside the hose. The three way valve puts the vacuum control right at your hands right where you are working so you don't have to mess with reaching for the pump controls while your trying to do all the other stuff.
Seems to be a pretty hefty bridge there?
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Jason Rodgers
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- Joined: Fri Jan 06, 2012 4:05 pm
- Location: Portland, OR
Re: barebones bridge vacuum clamp
Randy Roberts wrote:If you have access to needles
-Ruining perfectly good wood, one day at a time.
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Randy Roberts
- Posts: 466
- Joined: Sat Jan 07, 2012 9:11 pm
- Location: Omaha, NE (a suburb of Iowa)
Re: barebones bridge vacuum clamp
Ahem....
I believe Bob is in the medical field if I'm remembering correctly from some post from the past.
Or in your case, just go get a dog. I would imagine most Vets would be willing to help you out (at least if you behaved yourself).
I believe Bob is in the medical field if I'm remembering correctly from some post from the past.
Or in your case, just go get a dog. I would imagine most Vets would be willing to help you out (at least if you behaved yourself).
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Bob Hammond
- Posts: 638
- Joined: Sun Jul 22, 2012 4:13 pm
Re: barebones bridge vacuum clamp
A hefty bridge, you say? The word 'massive' came to my mind. Aside from the self-imposed restriction on salvaged materials, this thingie was built with the idea of making a small 4-string instrument for camping & festivals, maybe a baritone uke, but I didn't have enough material for that. I had originally planned (too strong a word) to have a mandolin tailpiece & bridge arrangement, but it sounded very thin, too much like a banjo. But when I put on some lightweight guitar strings and slipped this block under the strings, it sounded much more like a guitar. So, I just shaped it a bit, and I might carve it down, now that it's glued on.
It has a 20" scale length, with a soundboard of the finest aged (5yrs at least!) Home Depot spruce 2x4, and a body & neck of cherry. The fingerboard and bridge are bloodwood, and the bindings would have been bloodwood too, but they kept snapping like toasted taco shells (does kiln-drying make bloodwood too crispy?).
As for the details of the clamp gizmo, the needle is attached to a TB syringe that is held by the dial-indicator stand, and attached with a short length of rubber tubing to the rigid pressure line. I'm now semi-retired from medical research, but I'll scrounge around for a stopcock and arterial pressure line, because that would be easier to handle.
One more comment, is that the blue Irwin squeeze clamp over the tailblock does two things- It holds the instrument down for working on it, and it also compresses the foam so as to seal the entry hole of the needle. Here's a closer look:
It has a 20" scale length, with a soundboard of the finest aged (5yrs at least!) Home Depot spruce 2x4, and a body & neck of cherry. The fingerboard and bridge are bloodwood, and the bindings would have been bloodwood too, but they kept snapping like toasted taco shells (does kiln-drying make bloodwood too crispy?).
As for the details of the clamp gizmo, the needle is attached to a TB syringe that is held by the dial-indicator stand, and attached with a short length of rubber tubing to the rigid pressure line. I'm now semi-retired from medical research, but I'll scrounge around for a stopcock and arterial pressure line, because that would be easier to handle.
One more comment, is that the blue Irwin squeeze clamp over the tailblock does two things- It holds the instrument down for working on it, and it also compresses the foam so as to seal the entry hole of the needle. Here's a closer look:
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Randy Roberts
- Posts: 466
- Joined: Sat Jan 07, 2012 9:11 pm
- Location: Omaha, NE (a suburb of Iowa)
Re: barebones bridge vacuum clamp
Bob,
If you are semi-retiring, also grab some I.V. fluid bags. The injection port on them works great for gluing onto a vacuum membrane and using it for your vacuum entry point.
While you're at it grab a couple of laminar flow workstations to use as a sanding bench, a couple microscopes for inlay work, and a couple scanning electron microscopes for checking for degree of runout, and I'll meet you in the alley...
If you are semi-retiring, also grab some I.V. fluid bags. The injection port on them works great for gluing onto a vacuum membrane and using it for your vacuum entry point.
While you're at it grab a couple of laminar flow workstations to use as a sanding bench, a couple microscopes for inlay work, and a couple scanning electron microscopes for checking for degree of runout, and I'll meet you in the alley...
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Bob Hammond
- Posts: 638
- Joined: Sun Jul 22, 2012 4:13 pm
Re: barebones bridge vacuum clamp
Hah!. Kinda like Johnny Cash "One Piece at a Time"?
I have scored some great bargains at the hospital's excess inventory sale. I picked up a bedside vacuum aspirator pump and a Gast 2 gal. hotdog compressor/vac, both in excellent condition for $20 total. But I missed out on the mint 14" Rockwell bandsaw that went for $30, and a Bausch & Lomb desktop operating microscope that was tipped into the dumpster (sniff-sniff).
I have scored some great bargains at the hospital's excess inventory sale. I picked up a bedside vacuum aspirator pump and a Gast 2 gal. hotdog compressor/vac, both in excellent condition for $20 total. But I missed out on the mint 14" Rockwell bandsaw that went for $30, and a Bausch & Lomb desktop operating microscope that was tipped into the dumpster (sniff-sniff).