Most useful sizes for vacuum chucks?

[Dan Forman]

Made a four inch vac chuck following Steve's directions, wondering what other sizes would be the most useful. What are your favorite sizes? Thanks,

Dan

[Tim Boger]

Morning Dan .... I'm also interested in the popular sizes on vacuum chucks, sounds like a fun part of the project.

I have also posted a question about the size of pump but have not got any replies yet.

Have you acquired a pump yet?

Tim

[Thom Sturgill]

I made mine from PVC fittings backed by 1 1/2" of MDF. I have a small one from a 2 1/2" fitting, a 3", 4" and 6" and am going to make a flat-ish dish (slightly hollowed) covered with craft foam as big as the biggest sheet of craft foam I can find. The holding power is related to the diameter, the smaller two were almost unusable and the 4" coupling works great. I have used the 6" a couple of times, but it is too big for many of my turnings. Note that the 4" coupling is almost 5 1/2" OD. Shoirt sections of heavy pipe would work well also, but I would stay away from the light S&D pipe.

[Roger Chandler]

I have a 3 inch, 4 inch and a 6 inch vacuum chuck. I have had a couple of times when a 2" would have been nice. When you reduce the size of the chuck, the holding power diminishes also, so you can go too small.

[Peter Fabricius]

Hi All;
The holding power is related to the diameter in as much as the larger diameters will give you a larger "volume" on the inside of your bowl. It is the volume that magnifies the holding power / pounds per square foot pressure on the bowl bottom. Remember too much suction and a bowl can implode. If you have a bowl with a flat edge it can be attached to the flat chuck because it uses the volume inside the bowl to create the needed suction. If you attach a flat piece to the flat chuck all you have is a 1.5" diameter hole against the flat piece and that is just not enough volume to hold it tight.
I have two 4" PVC chucks and a 8" flat chuck with craft foam glued on. The little 4" one is shown on my lathe in the "Vacuum System Completed thread". A longer version is also made to accomodate any deeper bowls.
I will look for a piece of 6" PVC so I have that as well. The ends are covered with a. craft foam glued on; b. a rubber "O" ring cut into the edge; and c. the craft foam glued on the flat melamine disk with a 1.5" hole in the middle. All the chucks are threaded with the Beall spindle tap 1.25" for my Nova DVR XP.

Bob Hamilton has a video of his vacuum chucks and that is where I got my inspiration and technical instructions.
thanks
Peter F.

[Keith Palmer]

.. am going to make a flat-ish dish (slightly hollowed) covered with craft foam as big as the biggest sheet of craft foam I can find.

I found a roll of craft foam at my local Jo-Ann store 3 foot wide by i can't remember how long. But buying the whole roll was cheaper than buying three 11x14 sheets. Besides allowing me to use bigger pieces of the foam, it also reduces waste for squeezing in smaller cuts.

[Bernie Weishapl]

I have a 2 1/2, 4, and 6 pvc chucks glued into MDF. I found the same foam at Jo-Ann's as Keith and it works great.

[Thom Sturgill]

I found a roll of craft foam at my local Jo-Ann store 3 foot wide by i can't remember how long. But buying the whole roll was cheaper than buying three 11x14 sheets. Besides allowing me to use bigger pieces of the foam, it also reduces waste for squeezing in smaller cuts.
:eek: It won't be that big! My lathe only has a 16" swing!!!

[Dan Forman]

Thanks. I gather that the flat dish uses the rim rather than the inside of the bowl to seal? Is it used for smaller bowls and such, where a small pvc pipe would limit the volume of air to hold it? Are there other advantages to the flat chuck?
Dan