Vacuum Chucking Question

[Glen Blanchard]

Man, the noise of this vortex is getting louder every day!!!

I have a vacuum that I use with a bag when laminating, veneering and such. If memory serves it's this one from Woodcraft:

http://www.woodcraft.com/product/2005086/19303/vacuum-veneering-kit-with-pump-and-36-x-54-vinyl-bag.aspx

This is a continuous running vacuum pump. Would this be suitable/adequate for vacuum chucking on a lathe, permitting me to just buy a few of the accessories needed to be up and running?

[David Gilbert]

Glen,

If you already have this vacuum pump then you have little to lose by using it. I bought my vacuum adapter and hub from JT Turning Tools and they sell a vacuum pump that pulls 4.2 CFM (Cubic Feet per Minute) which is a lot more than the 0.8 for the pump that you listed. The problem that your smaller pump will suffer is that it may not be able to get ahead of the air leaks or the porous nature of some of our wood. There are a number of connections that can leak and they can add up to less vacuum than you need. That being said I am regularly using a vacuum pump that I bought for $25 that probably doesn't pull anywhere near the 4.2 CFM that JT Turning Tools is selling. You don't need or even want a perfect vacuum because you can implode a turning with too much vacuum (very exciting when this happens and a good reason to wear a face shield). But you do want one that can keep up with the air leaks. I would give it a try. I really like the flexibility my vacuum system provides. I use it on almost every bowl and platter that I make.

Cheers,
David

[Jeffrey J Smith]

Glen:
I agree with David - at .8 CFM, that pump will have a tough time keeping up with the loss in the system to be safe. I had used a Gast rocking piston style pump that I picked up for about $50.00 or so a while back. At 3CFM it worked alright, but I was never able to draw much more than 20" of vacuum on my Jet 1642. That's with both a Woodfast adapter (cheap) and finally a Oneway Adapter made for the Jet.

When I stepped up to a bigger lathe, I found an excellent deal on a Gast rotary vane pump then I got the adapter and hub from JT turning tools David mentioned. The difference is astounding. This combination is capable of actually pegging the gauge. It gives me a margin of safety when turning larger pieces.

I haven't tested the new system with the old pump, but I'd guess that the better seals on the JT adapter and hub would significantly increase its performance, too.

There's a wealth of information out there on vacuum chucking, particularly on the AAW site and forum (I think that John Giem's thread there has good info and is permanently available). John's also had a couple of articles in the American Woodturner that are helpfull .

Jeff

[Dave Mueller]

Glen,
I am probably a wild card with my suggestion, but I have been using a $115 pump from Harbor Freight http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html that has performed very well for me. I also bought a rotary vacuum adapter from the Stubby lathe dealer http://stubbylatheusa.com/cgi-bin/onlinestore.py#Rotary Vacuum Adaptor Kit for less than $40 and it works great. Just add a piece of threaded lamp tubing from Lowes http://www.lowes.com/pd_42370-1811-884L_4294896173__?productId=3659590&Ns=p_product_qty_sales_dollar|1. I also use the same pump to vacuum impregnate wood with TurnTex's Cactus Juice, which requires a pretty hard vacuum. This pump goes right down to 29" very quickly. I had a Gast pump before and it did not go below 22" with the rest of the same system.

If you get the Harbor Freight pump, the only issue is oil mist out of the exhaust. The first time I used it, there was so much mist my shop looked like there had been a fire. I made a simple filter that I used to replace the one that came with the pump and it stopped the oil mist completely. If you want details on the filter, let me know. Attached are some pictures of the setup, including the white filter on the pump. I put the pump in an enclosure, which necessitated a cooling fan and vent, but out in the open would work.
Dave
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