[OP]
Contributor
I am putting together a vacuum chuck system for my PM3520A and have a Gast vacuum pump on order. I am now trying to decide which rotary vacuum adapter I should get.
Is the rotary vacuum adapter sold by Craft Supplies that they call "Precision Machine Rotary Vacuum Chuck Adapter" the same as sold by JT Turning Tools? Here are a couple of photos of the Craft Supplies offering.
rotrary adapter III.jpgrotary adapter II.jpg
Member
I don't think they're the same. But keep in mind it's just a round thing with a hole drilled through it, some o-rings one end and a couple $1 bearings glued into the other -- and you have a $4000 machine that makes round things.
Moderator
They do look very similar and as mentioned, are extremely simple in design so I expect the function to be the same. The one from Craft Supplies is a lot cheaper!
I bought the bearings and parts to build one from scratch but have not done it yet. I plan to machine one from aluminum similar to what you pictured but construction can be simpler than that. I can imagine turning a piece from lignum vitae that would hold the o-rings and adapt to the bearing. Also, Joe Woodworker has instructions and parts for a design that could easily be adapted to fit the PM lathe: http://www.joewoodworker.com/veneeri...umchucking.htm
If you haven't see Joe's web site he has a lot of good info on building vacuum chucks, etc as well as a more complex vacuum system suitable for vacuum bagging and clamping as well as vacuum chucking on the lathe. He sells everything you might need at extremely good prices, including an excellent vacuum chuck gasket material.
I currently have the Oneway adapter and it is a pain to use since the handwheel must be removed and the adapter fastened in place. Some people leave it in place but I do a lot of spindle turning and need access through the headstock spindle. I like the design with the o-rings.
JKJ
Member
I have the JT Turning adapter on my 3520b. It sure is nice to be able to push it in and remove it as quickly, so I highly recommend it. I've owned it for years with no problems. It has two o-rings, I see the Craft Supply version has 3. If price is the same between them, I might go for the Craft Supply version simply because of the extra O ring.
Moderator
I have one of JT's original vacuum adapters and it was made specifically for my lathe! I highly recommend Tom's vacuum adapter!!
One of the issues Tom ran into when figuring out the design was discovering the internal diameters of the handwheels on lathes were not consistent. When dealing with a vacuum, you have to have a tight fit or you will not create a vacuum. Tom's solution was to create a matched handwheel and vacuum adapter for each model of lathe. Things may have changed since I got my adapter, so I highly recommend going to the JT website and reading about the adapter he developed. Please note that on the info page for the Powermatic 3520 A & B, it states that the adapter will not work with the stock lathe - which leads me to believe that he is still machining a matched set.
Steve
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Contributor
I like using the vicmarc system. Your Chuck holds the adapter, so it is very fast to switch between traditional chuck turning and vacuum chucking.
I already use vicmarc chucks, so I did not have to buy the adapter.
http://www.woodworkersemporium.com/Vicmarc_V01216/
Contributor
Alan, from the Craft Supplies artwork and description, I don't think they're the same thing. I suggest you just call Tom Steyer at JT Turning Tools and ask him. Craft Supplies describes theirs as a "double row, dual thrust" bearing. Their unit may be good, but I'm not sure what that means. Sounds like a marketing description. I know that Steyer uses two double-sealed, double-shielded bearings, and the housing is machined with CNC equipment from a single billet of aircraft aluminum. His don't leak.But if you're pulling a vacuum that is strong enough, with high enough CFM, some leakage is o.k.
Member
That looks pretty interesting Michael and I also have Vicmarc chucks. I can't seem to find much info online about these though. Would love to see a video of how they work.
Doug
Originally Posted by Michael Schneider
Member
I just spoke to Tom this afternoon about a wheel/adapter/hub for my G0766, which I already have a Ghast setup. I was waiting for him to get settled after being at a SWAT the past weekend. I can post an update and pictures when I receive mine.
Member
Alan, just to muddy the water, I have made a few from HDPE round stock, a sealed wheel bearing and a brass fitting. Buy a fitting to fit your air hose from somewhere like Lowes and take that to an auto parts store and have them pick a bearing with a close fit for one end of the fitting. Either epoxy it into the inner race or put a nut on each side of the bearings inner race to hold the fitting in place. Now simple turn the HDPE round stock to shape, similar to the one you posted above and drill a nice tight fit for the outside of the bearing in the HDPE and press the bearing in. Use a parting tool to cut a couple of grooves in the nose that goes into the lathes hand wheel. It's fun to make and cheap, I'm thinking something like 10 to 15 bucks for parts and it works great.
Member
I don't know if it is more fun making stuff on the wood lathe or making new toys for the wood lathe.
Here is my adapter. Two 6203 double sealed bearings sealed up with a shaft seal. I thought of using three o-rings but I was thinking I could leave a boss on my shaft for a hose washer to seal against.
DSCF9008.JPG
DSCF9010.JPG
It appears to be a good solution but I'm still building my new vacuum system and haven't tried it out yet.
Last edited by Larry Copas; 09-03-2016 at 12:16 PM. Reason: Bearing should have 6203, not 6303
Larry
Contributor
As long as we are muddying the water:-) , here is one I made recently to fit more than one lathe. It uses a lamp rod to go all the way through the headstock to a morse taper adapter that is small enough to thread a cup chuck over it. The MT adapter and the bearing end are made from black walnut. The coupler is made from a barbed fitting machined down to fit through two 3/8 ID x 7/8 OD bearings. It can move from lathe to lathe by putting a longer or shorter lamp rod in it. Or, by running the larger piece near the coupler end up against the outboard end of the spindle.
[OP]
Contributor
Larry, very nice design. Tell us more about the shaft seal please!
Contributor
Jeramie, Tom has a good setup for the G0766. I think the first G0766 he made one for was mine last year. Here's the review I did then, with pics. http://www.sawmillcreek.org/showthre...6-(and-others)
Contributor
Very interesting design, Larry. Could you elaborate a bit? I'm guessing from the pics that your bearing assembly fits inside that housing, which then threads onto the outboard end of the spindle in place of the OEM handwheel? It looks like you've threaded the outboard end of the housing/handwheel for a fitting to connect the hose. If that's right, doesn't that defeat the purpose of the bearings, since the housing will rotate with the spindle? A more minor point, won't you have to take both the housing and the bearing assembly off in order to use your knockout bar? Or maybe use a very thin knockout bar?
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