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PostPosted: Wed Sep 23, 2009 11:57 am 
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Here is a plan for a Vacuum Bridge Clamp I made. The bottom needs to be sealed with a good vacuum gasket tape. I used two rows of the 3/8" x 1/8" size from http://www.veneersupplies.com/default.php?cPath=60_46. The rest of the drawing should be self explanatory.
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BridgeVacuumClamp.pdf


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PostPosted: Thu Sep 24, 2009 6:30 am 
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Here's a few photos:
You can see I left the membrane a little loose so it could get down around the bridge as good as possible.
Attachment:
DSCF0187.JPG


Here is a photo from when I did the initial testing. Since then I have used it with hot hide glue to put a bridge on my walnut/sitka OM and it worked great.
Attachment:
DSCF0189.JPG


Closeup
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DSCF0190.JPG


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PostPosted: Fri Sep 25, 2009 6:22 pm 
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Hey Steve,

Great Stuff !

Thanks - Luc


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PostPosted: Sun Sep 27, 2009 12:40 pm 
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verhoevenc wrote:
Estimated project cost? Material sources?
Chris


Chris, cost depends on how much and what you buy, most of this I had laying around. The callouts on the drawing will show the part#/sources used except for delrin which is available at McMaster Carr and other industrial suppliers.

Thanks Luc!

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PostPosted: Sun Sep 27, 2009 2:04 pm 
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Thanks for making the effort to share Steven.

Cheers

Kim


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PostPosted: Mon Oct 19, 2009 3:03 pm 
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Great tute Steve. I've been putting off making one, but you've pushed me over the edge. How long do you leave it on with HHG? Do you take it off momentarily to clean glue squeeze out during the process?

Thanks

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PostPosted: Sat Oct 24, 2009 5:05 pm 
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Woody, I've only used it on the one, so far. I left it on for 10-15 minutes, cleaned up the squeeze-out then put it back on for 30 minutes. Probably overkill but so far it seems to have worked well.

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PostPosted: Mon Oct 26, 2009 3:04 pm 
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Hi Steve,
Isn't there a foam gasket that would be attached to the bottom delrin ring? I don't see it on the plan and it seems to me that similar rigs I've seen have some sort of gasket. It appears that your plan would have the hard plastic contact the top, am I wrong?

Rene


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PostPosted: Mon Oct 26, 2009 3:16 pm 
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Rene wrote:
Hi Steve,
Isn't there a foam gasket that would be attached to the bottom delrin ring? I don't see it on the plan and it seems to me that similar rigs I've seen have some sort of gasket. It appears that your plan would have the hard plastic contact the top, am I wrong?

Rene
SteveSmith wrote:
Here is a plan for a Vacuum Bridge Clamp I made. The bottom needs to be sealed with a good vacuum gasket tape.

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PostPosted: Mon Oct 26, 2009 4:44 pm 
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Thanks for the drawing, Steve. Even gave us the screw numbers from McMaster!

1 Question: I have some UHMW kicking around that's plenty big. Does anyone know if UHMW is suitable for vacuum fixtures?

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PostPosted: Mon Oct 26, 2009 5:00 pm 
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Oops! Sorry, I don't know how I missed that. Thanks Bob!

Rene


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PostPosted: Wed Oct 28, 2009 9:08 pm 
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ClintB wrote:
Thanks for the drawing, Steve. Even gave us the screw numbers from McMaster!

1 Question: I have some UHMW kicking around that's plenty big. Does anyone know if UHMW is suitable for vacuum fixtures?


Yes, given that you can deal with:

1-It doesn't glue to anything with anything, really. The contact adhesive on your sealant tape will hold the tape in place well enough to work, but it'll slide around if you put a side-load on it.

2-It doesn't hold screws very well when tapped, so you'll need to use more and deeper tapped holes to hold the top plate down and you'll have to be very careful about stripping the threads.

Those two are annoying, but not insurmountable. If you have the option, I'd go with something like Delrin or Acrylic that'll hold a screw once it's tapped.

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PostPosted: Thu Oct 29, 2009 2:11 pm 
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Thanks Bob. I think I'll pass on the UHMW. Plenty of other good uses for the stuff. I don't really have trouble coming across delrin. It passes through our shop now and then (I'm a machinist too).

We have tons of aluminum lying around - just up for grabs. Would that be better or worse than delrin for vaccuum fixtures? My assumption is that the adhesion of the sealant tape would again be an issue.

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PostPosted: Thu Oct 29, 2009 9:31 pm 
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It'll stick to the aluminum, PSA works on it alright. Just make sure to clean it off with acetone or whatever to get any coolant off of it. Aluminum works as well or better than Delrin, and it holds threads best.

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PostPosted: Fri Oct 30, 2009 8:35 pm 
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Thanks again, Bob. I'll go with the aluminum. Cheers.

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PostPosted: Mon Nov 02, 2009 6:44 am 
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Guess I need to check in here more often. Thanks Bob for lending your experience!

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