Woodworker's Journal 2010-34-2, страница 21

finish objects. The contact point between wood and cylinder is a soft seal, often made from neoprene. Use of this type of material lets you avoid any marks on your turned objects. Different size cylinders allow for attaching variously sized objects.

Commercial systems come with a vacuum pump, rotary adapter, air hose, vacuum gauge (or regulator) and vacuum cylinders. Each item can be purchased separately, or the complete package can lie ordered with the cylinders threaded to fit your lathe's spindle size.

Finishing the Bottom of a Shallow Bowl

After explaining his vacuum system, John showed me the steps involved to reattach a shallow bowl to the lathe in order to turn the bottom. The howl was originally attached to the lathe using a scroll chuck grabbing a tenon (or foot) on the bowl's bottom. John needed lo clean up the inside ol the tenon to create a finished base.

With the bowl turned and sanded and still attached to the chuck, John removed that assembly from the lathe. He selected the medium-size vacuum cylinder and threaded it onto his lathe's headstock spindle. The vacuum system was already set up 011 the lathe, so the next step was to somehow reattach the bowl to the cylinder, getting it centered.

This is where things get a bit tricky: the object must be reattached to the lathe, keeping in mind that there are three axes, each of which could be out of alignment, ll can be done, but it might lake aw hile. Or you can get lucky and hit it right 011 the first try.

A Solution to Centering

The folks at Oneway Manufacturing have figured out an ingenious solution lo getting something centered bac k onto a lathe in a vacuum chuck: it's an adapter that screws onto a chuck, 'litis adapter allows the turner to keep the bowl or plale in the original scroll chuck, yet be able to reattach it to the tailstock spindle. Doing so

ensures that the plate or bowl will be aligned with the lathe's axes. Since John's bowl was already attached to a scroll chuck, he simply removed the chuck-and-bowl assembly from the lathe and affixed an adapter

10 the chuek. He then threaded the chuck onto the tailstock spindle. Presto ... immediate centering! From this point, he moved the tailstock down the bed of the lathe so that the inside of the bowl made contact with the vacuum cylinder. He opened the valve

011 the vacuum system, which attached the bowl 011 the headstock. It was centered! John removed the chuck from the back of the plate, and the result was complete access to turn the bottom of the bowl.

Critical Components:

There are several critical components (above) to this chucking system: a vacuum pump and regulator, a rotary adapter and air hose and the vacuum cylinders. Complete packages are available, or the parts can be purchased separately.

Woodworker's Journal April 2010

www.journal-plaza.net & www.freedowns.net

it