Archive for February, 2006

Various ways of chucking

Tuesday, February 7th, 2006

At tonight’s MWA meeting Jim Jacobs and Steve Tiedman demonstrated many ways to chuck wood onto a lathe. Drive centers, face plates, scroll chucks, even a vacuum chuck were presented. While I knew many of these from the various catalogues and web sites, it was great to see them in person and to get comments from people who have used them.

Of special interest to me were the various home-grown recipes. For example Steve showed how a low cost old fashioned dead center could be modified and used as a drive center. It is similar in performance to a Sorby steb center, but at a much lower cost.

For small objects it sometimes is sufficient to just cut one end into a rough taper. That can then directly be mounted into the morse taper, no chuck required at all!

Another method: turn a taper to fit the morse taper, with a plate on the thick end. Mount into the morse taper, drill a small hole, glue in a nail and fashion the head of the nail into a point. This can be used as drive center for small projects or spindles. It is very save, should the wood catch it would just stop spinning. It is also a great training tool to learn to work with light pressure.

To turn the body part of miniature birdhouses, Jim fashioned a mandrel. While for the body of a miniature birdhouse could simply use a dowel and drill a hole through it, it is hard to get that hole perfectly concentric. Jim’s mandrel solves that problem: It is square on one end to allow it to quickly mount into a scroll chuck. The remainder is turned round to the diameter of the hole drilled into the future birdhouse body. The other end of the mandrel has perpendicular cut through the center. The tail stock will slightly pry the wood apart, and thus securing the body of the birdhouse on the mandrel. A simply but effective solution!

To turn the perches for those miniature birdhouses Jim has another trick: A block is chucked into a scroll chuck, and a hole drilled into the wood block, easiest with a Jacobs chuck in the tail stock as Steve demonstrated. Now a dowel, slightly tapered is pushed into the wood block. Et voila, a simple way to chuck very small items.

Another MWA member demonstrated how simple (and cheap!) PVC endcap from the plumbing department can be mounted onto a chuck. Wrap some non-skid fabric from the home department around it, and it can be used to reverse-chuck a bowl to finish most of the bottom.

Jim used another type of endcap to turn spheres. That endcap was about 5” in diameter, and the closed end has a square protrusion, which fit perfectly into a chuck. A spherical body would fit perfectly into the open end. To support the tail-stock end, Jim removed the point from a live center, leaving just the cup. To prevent the wood from marring he used a hose washer between the cup and the sphere.

Another really helpful gadget: When turning a tenon for a scroll chuck, I like it to be as big as possible while at the same time being not so wide that the jaws protrude sideways from the chuck to reduce the danger of injury. Also for some types of chucks the tenon should be sized such that the jaws of the chuck form a circle, that maximizes the surface area on which they grip. I used to always set the chuck to the proper width, measure it with calipers and use that to gauge the size of the tenon. Jim and Steve had a handy little jig to make that easier: made from wood it looked like one end of an open ended wrench, the width of the opening being the perfect width for the tenon. And when made from wood of the proper thickness it can also be used to gauge the depth of the tenon. It should be deep enough to allow for maximum surface area, but it should never bottom out in the chuck. Handy little gadget, I’ll make one next time I’m in the shop!


Yours truly also got invited to show the Longworth Chuck. If you came to find out more about that chuck, click here to see my original post along with links to instructions.

All in all another very informative meeting. I learned a lot, and will have to visit the plumbing department soon!