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msrm
10-12-2002, 12:25 AM
Has anyone ever built a vacuum chuck? How
is the amount of vacuum controlled?

SGW
10-12-2002, 09:45 AM
Can't help you, at all, on this one! I would think one could use some kind of a "bleeder" valve to control the amount of vacuum, i.e. a controlled leak.

C. Tate
10-12-2002, 09:54 AM
Typically the amount of vacuum is constant on a chuck. The amount of holding force is directly proportional to the surface area of the work piece. You can buy a vacuum generator that works off of compressed air out of Mc Master Carr for less than $100. After that you need only build a two piece device that acts as your chuck. Since a picture is worth a 1000 words email me and I will send a photograph and detailed discription to you.

C. Tate

Stepside
10-12-2002, 10:45 AM
built several. The thing to remember is holding force is controlled by the inches of Mercury (in/Hg)produced and more important maintained as well as the surface area. The tighter the seal the lower volume needed. I have used a compressed air vacuum generator. They work fine, but your air compressor is going to work also. I have bought small vacuum pumps. They are somewhat spendy, but you are not running your air compressor. I have scrounged them from print shops and dentist offices. The "whipmaster" from the dentist office would "suck a golf ball through a garden hose", kinda like a girl I used to know.
I also used a three pin fence on most parts to get repeatability of location and to help control lateral movement.
Remember you cannot drill/mill into holding chamber.

bdarin
10-12-2002, 07:32 PM
Hey, Step...I knew that same girl! Small world.

C. Tate
10-14-2002, 08:01 AM
You better stop talking about that girl somebody may get offended and tell Neil that you are being crude and suggestive. I knew her too.


CT

Thrud
10-16-2002, 01:38 AM
Stepside:
I don't think I should tell you about the 10HP 3Phase 4" inlet vacuum pump I sold awhile ago - it really, really sucked.

Vacuum chucks work well on the mill and grinder, I have never seen a rotary one for lathes (the rotary vacuum interface would be expensive). Wood workers have used vacuum for laminating and work holding for 20 years.

Stepside
10-16-2002, 10:10 AM
I have built some vacuum patterns for router work that are 4 by 5 feet. When they are that big it really holds. Remember that force equals area time pressure difference.

abn
10-18-2002, 02:55 AM
I've been pricing Tri-Vacs on ebay because I have one I'm deciding whether to sell or keep and I notice two just ended with no bids and very reasonable start prices...

Item #'s
1778081065
1776705840

This one is very reasonable and may be a steal:
1776695484

There's a couple others on ebay...just thought you may be interested...at this point it looks like I'm keeping mine!!! Don't think I'd get enough to make it worth re-acquiring one when I need it.