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 Post subject: Vacuum Clamping Bridges
PostPosted: Tue Mar 20, 2018 11:38 pm 
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Joined: Wed Nov 12, 2014 10:02 am
Posts: 367
First name: Daniel
Last Name: Petrzelka
State: Washington
Country: United States
Focus: Build
I finally had a chance to try a vacuum bridge clamp - a whole new world.

LMII vacuum bridge clamp with a GAST DOA-P707-AA (FleaBay Score) pulling 24-25 in of Hg with a good seal. I also tried it with an older GAST DOA-101 and it worked equally well. The local Semi-truck repair shop had some really nice all brass 1/8" NPT to 1/8 tube quick connects that are wonderful. They allow the use of the more flexible 1/8" hose/tube, and look like they should last forever.

With the vacuum pump/clamp I'm able to apply glue, and have it clamped in 25 seconds or less - allowing me time to use hot hide glue up to 315g strength—which is way, way more than I have any need for, but its possible. I've always had success with the standard 162g hide glue from Behlen.

Hesh, I'm sure you'll have some thoughts ;) - but I'm having fun over here.

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You can see a little Instagram video of it in action here:
https://www.instagram.com/p/BgeLrT4guNZ/?taken-by=dpetrzelka




Ken had posted a great piece over at http://www.acousticguitarconstructionforum.com/ about making your own vacuum clamp for bridges here:

DIY Bridge Vacuum Clamp
http://acousticguitarconstructionforum.com/viewtopic.php?f=7&t=817




...


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PostPosted: Mon Mar 26, 2018 5:57 pm 
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First name: Mike
Last Name: Spector
City: ORANGE
State: TX
Zip/Postal Code: 77632
Country: USA
Focus: Build
Status: Amateur
I'm interested in either making or buying a small vacuum clamp setup. How long do you leave the rig running after setting it on the bridge?


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PostPosted: Mon Mar 26, 2018 6:13 pm 
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First name: Daniel
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I'm only getting started with this vacuum clamp—So take this as only one approach, but it's working so far.

For hot hide glue, 192g and 315g are the two I've tried, I vacuum clamp for 10-15 minutes, then clean up squeeze out.
I then clamp again for a minimum of 45min-1hr. After that I let they dry overnight before stringing up.

In the hide glue cure time thread some debate started about the efficacy of vacuum clamping bridges and usage with hide glue. Lots of opinions. So far I've had success, but can't speak to first hand experience with longevity of the glue-up. I have no reason to suspect it will fail vs a traditionally clamped bridge with a hide glued joint.

Robbie O'Brien talks briefly about it this Tips du Jour video

https://www.youtube.com/watch?v=9FTG5p2dsBA

https://www.youtube.com/watch?v=qRqCp1zKOEk

He is using a Titebond style glue I believe, but maybe he can weigh in on HHG usage?


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PostPosted: Tue Mar 27, 2018 10:14 pm 
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First name: Bob
Last Name: Gramann
City: Fredericksburg
State: VA
Zip/Postal Code: 22408
Country: USA
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I’ve been vacuum clamping my bridges for several years now. I preheat the bridge to extend my working time. Usually about five minutes after I apply the clamp, I remove it and clean up the squeezeout. After that, I clamp it for another 2 hours (or more depending on when I can get back to turn off the pump). I wait to string it up until the next day whether I use 192g or 315g glue (I haven’t had a bridge pop since I started using 315g).

I started using the vacuum clamp because I had problems with bridges distorting under clamping pressure some times. The vacuum clamp applies pressure about as evenly as can be done. And it sure is easier than setting internal and external cauls and three through the soundhole clamps.



These users thanked the author bobgramann for the post: dpetrzelka (Wed Mar 28, 2018 9:10 am)
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PostPosted: Sun Apr 01, 2018 12:12 pm 
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Joined: Sat Dec 28, 2013 10:06 am
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First name: Mike
Last Name: Spector
City: ORANGE
State: TX
Zip/Postal Code: 77632
Country: USA
Focus: Build
Status: Amateur
I'm used to cutting the saddle slot before I glue on the bridge. Does the vacuum pull down without moving the bridge ? It almost looks like you could recheck the slot measurements even with the thing pulling down.


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PostPosted: Sun Apr 01, 2018 4:29 pm 
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Joined: Mon Oct 17, 2011 4:10 pm
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First name: Bob
Last Name: Gramann
City: Fredericksburg
State: VA
Zip/Postal Code: 22408
Country: USA
Focus: Build
Status: Professional
I locate the bridge, drill the two outer holes, and hold it in position with the StewMac slick tapered pins. Personally, I wouldn’t expect the bridge to stay exactly where I left it with any clamping system unless it was pinned.


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PostPosted: Sun Apr 01, 2018 4:49 pm 
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Joined: Wed Nov 12, 2014 10:02 am
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First name: Daniel
Last Name: Petrzelka
State: Washington
Country: United States
Focus: Build
I pin mine as well - either as Bob described above for replacement bridges or with small metal pins through the saddle slot


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