Article: Vacuum Chucking for the Lathe
If
there is any tool in the wood shop that could be considered a “consumer”,
the lathe would be it. The cost of the lathe is almost immaterial unless you’re
buying one of the large, premium tools. The real investment is in the tools,
sharpening and accessories!
At a meeting of the Bucks Woodturners, my local chapter of the American Association of Woodturners, renowned bowl turner David Lancaster demonstrated his techniques for using a vacuum chuck in his production turning. The ability to mount and easily remount the work piece is a very attractive feature of this attachment method and the ability to do so without marring the project is a plus.
A short tutorial in vacuum chucking
Vacuum chucking takes advantage of creating a difference in air pressure between the inside of the turning and the ambient atmosphere. The greater the difference, the stronger the hold and with a high quality system, rather large items can be held securely on the lathe.
There are thee major sets of components that make up a vacuum chucking system. Generally speaking, they include the vacuum source (typically a vacuum pump), the spindle adapter that allows the vacuum source to physically connect to the headstock and spindle of the lathe and the chuck itself. Of course there are a number of supporting pieces and parts that bring this all together, such as electrical components to supply and cut off power to the vacuum source, tubing to bridge between the vacuum source and other components, a vacuum gauge to indicate the level of “pull” (negative pressure) and a small valve to allow control of the negative pressure applied to the turning by the system. That last one is important--too much vacuum can damage or destroy your work piece!
So, to build a vacuum chucking system for your lathe, you will need a vacuum source, such as a Gast vacuum pump, a vacuum meter, a small valve, flexible tubing and appropriate connectors (typically 1/4" and 3/8" NPT as well as standard quick connect air tool connectors), a vacuum spindle adapter and some form of drum chuck that is threaded to match your lathe’s spindle. Sounds simple? Actually, it is.
The Saws ’N Dust solution for the OneWay 1018
Taking advantage of the sage advise from Texas turner Johnny
Tolly, fellow woodworker Jim Tienken and I recently put together our vacuum
chucking systems. Jim has a NOVA 3000 and I have a OneWay 1018 lathe. We choose
to have Johnny put together a kit of components, excluding the spindle vacuum
adapters, drum chucks and pumps. While we could have sourced these items,
we believe that we got much higher quality and saved time and money by purchasing
these items 
from
Johnny. Had we not already found some brand new, but surplus Gast vacuum pumps
at an attractive price, we would have purchased these from Mr. Tolly, also.
(We recommend that you work with Johnny if you decide to add vacuum chucking
to your own turning activities...he’s a real expert. He also has some
nice articles on the Turningwood
web site in the How-to Articles section)
Jim
and I decided to purchase the EZ-Vacuum adapter, available from Craft Supplies
or Packard Woodworks
to make the physical connection to our lathes as a lower cost alternative
to the excellent OneWay spindle adapter. One hindsight, I believe that the
OneWay adapter would have been a better choice and suspect I’ll move
to that product as I use this system more and more.
Deciding
on the drum chuck was a harder decision. It’s relatively easy to construct
these items in your shop, and at first that was the plan of record. But after
experimenting with the first one, I decided to go directly to the excellent
machined aluminum OneWay vacuum drum chuck.
Using a vacuum chuck takes a little getting used to and some practice in
mounting your object perfectly centered. If you start with a standard scroll
chuck, there are adapters available that will allow you to mount that chuck
on your tailstock backwards in order to keep the project piece perfectly centered
as you bring it up to engage the drum and turn on the pump. Additionally,
it’s important to remember that the vacuum system can exert significant
force on your object. Care needs to be taken to insure that you don't crack
a thin vessel--a disappointing end to its viability. 
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