vac hold down using 3 different sizes of o rings

[stan kern]

This design is the best so far as with different o rings you get different hold down techiniques
with 4 of these hold downs ,you7 get a lot of vac power to hold a large surface area
Took about 40-45 minto make


http://youtu.be/rSQvrg2TKzE

also included is some testing

[Bruce Page]

Stan, what kind of vac pump do you use and how much pump does one need? I have been thinking of adding a vac system but I don't know where to start.

[stan kern]

i am using a gast vac pump 1/3 hp rated at 21 in mercury.Its from a veneer press.One could get quite clever and mount these hold downs and run sepaarte lines off a header w/valves to place a vac
in certain sections on a cnc table.
I have made many hold downs round ,square etc --this last bunch is the best

[Bruce Page]

We used to use small Welch pumps for vacuum holding back in my early machinist days. As I recall, they would pull ~18" at 7300' elevation. They would chug along all day, every day. They were quiet too.

[stan kern]

that would do the trick, i am amazed at how well this works and what it holds

[Rich Fennessey]

Now that looks pretty flexible. Only issue seems you might cut into it on a profile cut since you can't fit it all under the part. How deep is the surface of the hole from the edge? Looks like the air supply could be cut off if there was some part deformation into the air hole.

Is your O-ring glued to make the complete circuit or is it soft enough to just squeeze into the groove and make a seal? I've got a Welch vac pump I'm going to put into service soon.

[Keith Outten]

Bruce,

I built the Project EVS vac from Joe Woodworkers web site, it works well on my CNC machine and for holding parts for hand routing, etc.

http://www.joewoodworker.com/veneering/EVS/concept.htm

I had a small Gast compressor that I reversed the connections to use the inlet for vac service. I contacted Gast to verify that my compressor would work as a vacuum source and based on a model search it was good to go. Some compressor models cannot be used for vacuum. My EVS vac is compact and portable, everything I needed was in the kit except the PVC pipe as I recall.
.

[Bruce Page]

Thanks Keith, I'll give that a thorough read. It looks pretty nice. Camaster is supposed to be coming out with some sort of a “vacuum box” setup soon. It sounds interesting.

[stan kern]

i use a layer of a porous 1/8 panel when i cut through then i can safely cut through by 1/16in,the o rings just sit in the groove and when sucked down they are almost touching the plastic