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Can anyone tell me the best way to hold on a vacuum pump...I have been using foam with a hole cut in the middle..and it holds great..but the pump has so much pressure it just pulls the foam inside out which eventually tears...and I do have it glued to the rim....
I might be able to help you but I don't understand your situation... some specifics?
The foam is about a 1/2 thick glued to the rim that holes the bowl with a center hole about 1 inch in the center...when you pull a vacuum it holds for awhile..but having so much pressure it pulls the foam inside out..tearing it from the rim which loses vaccum
Try using a thinner foam seal. I use foam board from Walmart which is apx.1/8" thick on my vacuum chucks. It has a peel off on the sticky side and different color on the foam side. It works fine, I sometime do some carving on the bottom of my bowls and it may take 2 hours and it is still holding good. Cheap and easy to replace.
Yep, peel and stick 1/8 thick foam gets a good seal for me.
Does your set up include a bleeder valve that allows you to regulate the amount of vacuum being applied? I find full vacuum is seldom needed to securely hold a piece.
You should be using closed cell foam sheets that are thin like the type that Fred suggested. I use the type that doesn't have adhesive and wrap tape Around the outside to hold it down. Then I just cut an X in the center.
Another more elegant solution is to make a molded seal using Oogoo as described in American Woodturner a couple years ago.
That's exactly what I was going to suggest! In some cases the full vacuum can be so strong to break the turning (large chuck area, thin wall, weaker wood).Quote:
Originally Posted by Dwight Rutherford
In his instructions, Joe Woodworker has a picture of what he recommends:
Attachment 371195
The vacuum line connects to the bottom and the rotary adapter connects to the right. The valve adjusts the amount of vacuum to the chuck. It's best to put a breather/filter on the intake at the valve to keep sawdust from getting sucked into the pump. I like the vacuum gauge right on the manifold.
More info here: https://www.joewoodworker.com/veneer...umchucking.htm
Joe is a great guy for info. He doesn't even seem to care if you don't want to buy stuff from him (but I did anyway)
JKJ
To add to Fred, I saw the outer edge of the thin sheet rolled over the PVC piece and some masking tape used to seal down the outer edge. Works like a charm until you cut the 1/8" sheet on the face.Quote:
Originally Posted by Fred Belknap
The thin foam sheets that I used were from an arts/crafts store. They were peel and stick, and I cut them a little larger than the holders that I made. Put a small hole in the center, and use it till it wears out....then replace with a new piece. Of course, the sticky side went against the rim of the vac chuck/holder. 😊
I agree with others, thin closed cell foam. For my 4" chuck I get the foam at the Walmart crafts, seem like 8" X 6" 50 sheets for around $5.00. You should still have a bleed valve in your system that can be used for reducing vacuum on thin fragile pieces and other things.
Agreed, thin closed cell foam with sticky back. Or another suggestion if you want to keep using what you have is to cut the hole larger than 1".
I use the same foam as others, but like Pat said, cut the hole larger. I cut the inside out of the foam so that all that remains is the ring around the chuck. That way, there is not much foam area for the vacuum pump to affect. If you want to try something commercial, look at Rubber Chucky. I have a couple of them and they are excellent.