Instructions for PVC-based vacuum chucks?

[Greg Ketell]

I'm building my own vacuum chucks out of PVC/ABS unions on 2" MDF backing plates with CA-reinforced, threads. So far I've made a 5", a 4" and a 2.5".

I just can't figure out what to use for the "gasket" material. I bought several types of weather stripping but none of them can make the curves, especially on the smaller chucks.

http://sawmillcreek.org/attachment.php?attachmentid=137586&stc=1&d=1262841322
Here you can see where I tried to take one around the perimeter of the 5" and it just came off after the afternoon. On the 2.5" nothing could make the bend so I tried a "segmented" approach but it too didn't stick.

Can anyone point me to a good set of instructions? Or give ideas on good material to use?

Thanks in advance.

Below are a couple of pictures of the back for reference. You can see I thoroughly soaked everything important with thin CA.

[Steve Schlumpf]

Greg - I am sure there are lots of options but I use a thin sheet of closed cell foam (very light packing material), just cut a small slot in it for airflow and hold between the chuck and blank until the turning is seated. That way I don't worry about anything like glue or if the seal will hold.

[Gary DeWitt]

I have had a really good seal with just the PVC, having turned a nice rounded edge on it. Also used 1/8" thick closed cell foam, similar to wetsuit material, I found small pieces for sale at a foam shop.

[Thom Sturgill]

In my area, Michaels sells sheets (about 4x6) of self stick foam. Works great and I sometimes use it for jamb chucks as well. My vacuum chucks look about the same as yours except white pvc. I use CA glue on the threads to help form them and then use shellac to seal the unit.

[Chris Haas]

my wife had an old yoga pad laying around, it was like 3ft x 5ft. made a great gasket, should be real easy to find now at target or somewhere.

[Rick Hutcheson]

I just used a closed cell foam.
http://www.scrollsaws.com/images/Lathe/Vc010.JPG
http://www.scrollsaws.com/images/Lathe/VacChuk1.jpg

[Quinn McCarthy]

Veneer suppliers sells tape made just for vacuum chucking and vacuum clamping.

Here is the link.

http://www.veneersupplies.com/product_info.php?cPath=60_46&products_id=2320

I haven't tried any yet but plan on getting their vacuum chucking kit.

Quinn

[Peter Lamb]

I think you will find the thick seal shown in your pics will allow to much movement of your piece as you turn it. It is my experience that the thin material from Michaels is superior for this application and also cheap.
Peter

[Mauricio Ulloa]

Hi,

There is some foam that comes with the packing materials of any electronic equipment. This is about 1/32" white foam. I use it and it works great!

Hope this helps!

[John Grounds]

I got this idea from someone at the Virginia Symposium about three years ago but cannot remember his name. He suggested rubber/vinyl(?) hose from the big box store.

Carefully slit the hose length wise and secure the ends with electrical tape. No need to glue the hose.

http://theperfectcollection.com/460VAC1.JPG


It works,
John

[Bernie Weishapl]

I use closed cell foam on mine. Seals great and cheap. Here are mine.

[Bill Bolen]

+2 with What Bernie said. But....mine are prettier! I use blue ones...Bill...:-)

[Mike Peace]

I have had no problems with the Fun Foam from Michaels. Here is a picture of my 3 chucks all with the Fun Foam at a buck a sheet. Mine are put on with spray adhesive. When they get a little ratty, they are easily replaced.

[Dick Strauss]

Greg,
Don't use MDF in your chucks. MDF can separate quite easily and send your piece flying (DAMHIKT). Instead use any close grained hardwood and turn it with a shoulders to match the PVC fitting and your chuck.

As others have said, the thick weatherstripping you are showing is too thick and can allow the piece to shift as you turn without a live center engaged. White closed-cell foam sheets or neoprene will work well for the gasket material.

[Greg Ketell]

Thank you all for all your responses! I'm sure I'll find a solution in your notes.


I just used a closed cell foam.
http://www.scrollsaws.com/images/Lathe/Vc010.JPG
http://www.scrollsaws.com/images/Lathe/VacChuk1.jpg

That is what I used, Rick. Except mine was 1/2" thick by 1-1/4" thick.


In my area, Michaels sells sheets (about 4x6) of self stick foam. Works great and I sometimes use it for jamb chucks as well. My vacuum chucks look about the same as yours except white pvc. I use CA glue on the threads to help form them and then use shellac to seal the unit.


I think you will find the thick seal shown in your pics will allow to much movement of your piece as you turn it. It is my experience that the thin material from Michaels is superior for this application and also cheap.
Peter

Ok, I need to go to Michael's for other stuff anyway. I'll pick some up tomorrow.


I got this idea from someone at the Virginia Symposium about three years ago but cannot remember his name. He suggested rubber/vinyl(?) hose from the big box store.

Carefully slit the hose length wise and secure the ends with electrical tape. No need to glue the hose.

http://theperfectcollection.com/460VAC1.JPG


It works,
John

I REALLY like this idea!



I use closed cell foam on mine. Seals great and cheap. Here are mine.

Is that the Michael's foam?

GK

[Greg Ketell]

I finished the vacuum system this weekend. Thanks to Steve's great "how to" the build went flawlessly.

After pricing the spindle bearing adapter that Steve used I chose to build my own out of Corian. I glued 5 layers of corian together and then turned it to fit. I epoxied the bearing into place and used the epoxy to seal over all the gaps in the bearing as well.

http://sawmillcreek.org/attachment.php?attachmentid=139888&stc=1&d=1264555941

Then, per our discussion above, I went to Michael's and bought some of their self-stick craft foam and used that as the chuck seals.
http://sawmillcreek.org/attachment.php?attachmentid=139887&stc=1&d=1264555941

With just the hoses I can pull -27" Hg. With the spindle adapter with the lathe running I can pull -26". But when I first put the chucks on it dropped down to -19". WOW, that MDF is porous stuff.

After sealing the MDF with thick CA I now get
http://sawmillcreek.org/attachment.php?attachmentid=139889&stc=1&d=1264556448

WOOHOOOO.... Thank you everyone!!

GK

[Jeff Brockett]

I have used both mdf and Trex decking material left over from a deck job. I coat the MDF with a 50/50 titebond II/water mixture and let it dry. For the seal on the pvc I have used double stick "funny foam" that I buy at Micheals and Hobby Lobby and closed cell gasket material with a self adhesive backing that I find in sheets at a local gasket place. Put the PVC on the sheet of closed cell gasket material, trace around it leaving a little overhang and cut the center out. Works great!