Picasa Web Albums - montgomerycounty ...

Gmail Calendar Documents Photos Sites Groups Search More »

New Features | Help | Sign in

Program Chair Gary Guenther introduces J. Paul Fennell, while Bert Bleckwenn and David Jacobowitz look on.

Paul Fennell is very serious about the subtleties of his shapes and how they may be affected by the location and orientation in the tree from which the blank comes and by the drying process.

Paul is known for his elaborate piercing. This is a very simple example.

This is an example of the effect of some simple texturing.

When Paul makes hollow forms, they are very thin and extremely uniform. We'll find out how he does it in a minute.

Upon drying, the tangential shrinkage is significantly greater than the radial shrinkage for nearly all woods. This causes distortion and possibly cracking in turned vessels as they dry.

Here is a histogram of the T/R ratios for 258 species of wood, as drawn from data from the USDA Forest Products Laboratory. Woods with small ratios tend to be very stable, while those with large values distort and tend to crack. Look for a T/R list to be published in the October Newsletter in YMMV.

Side grain vessels distort greatly because one of the dimensions in their cross sections is longitudinal, and longitudinal shrinkage in wood is negligible. This one was quite oval. End-grain vessels remain much more symmetric.

When is a roughout dry? The simple way to find out is to weigh it each day until it achieves a constant weight. In this case, for Paul's small, relatively thin hollow form, equilibrium moisture content has been reached in about a week in the dry Arizona climate.

Tonight, Paul will be working with a piece of Bradford pear he got from a friend in North Carolina. No, that is not a typical Arizona wood, but it is wonderful for demonstrations. He begins between centers.

Paul first shapes the outside of his demonstration vessel with a bowl gouge or spindle gouge.

Bradford pear cuts like a dream and comes off in long, continuous ribbons.

Paul scrapes the sides with a heavy-duty, square-nose scraper, shortened by years of sharpening and use, to smooth out tool marks and subtly adjust the profile. Paul can make the outside as smooth as a baby's butt without sanding.

Paul makes many of his own tools. This is a shear scraper with a round shaft and a teardrop cutter.

This shear scraper can be easily tilted to the desired angle and is used without moving the tool rest. It gets into that otherwise difficult-to-reach location at the shoulder of the neck.

A closeup of the teardrop cutter. The sides are cut at 90 degrees.

While working between centers, Paul added a tenon and shoulder to the bottom end, and he now chucks the piece on that tenon. Note he is using the tail stock to maintain the axis before tightening the chuck.

Working without the tailstock momentarily, Paul uses a bowl gouge to form a small, cone-shaped tenon that fits inside his hollow tail center.

More scraping, with the tail stock up, to get the perfect shape and finish. Paul uses the tail stock as often as possible. This permits him to maintain excellent alignment and keep the piece as true as possible.

Time to move the tail stock back and remove the tenon with a gouge.

Paul uses the gouge to make a little dimple to provide a start for the drill that will make a starter hole down the full length of the interior.

Here is an overview of the air-powered "gun drill" that Paul uses to remove material very quickly and cleanly.

The gun drill has two holes in the end for air to blow out.

It looks like this.

Here is the "gun drill" in action. Paul measured carefully and bored a center hole the full length of the interior of the piece. You had to watch carefully because it was done very quickly.

Colin Poodry follows the action with Dad Clif.

Paul loves tools (don't we all?) and brought quite a bag full. Note that nearly all are homemade, and most are for hollowing. And it's time to start hollowing.

Here, Paul is opening up the drilled hole with a gouge. Note that the lathe is now running in the reverse direction. This permits him to work in a more comfortable fashion with his elbow close to his body. For safety, the chuck should be attached with a set screw, or be very tight, because it could unscrew itself going in this direction.

Paul can hollow most of a tall shape like this with a straight tool. He only uses the angled tool in the shoulder area.

Paul's homemade angled hollowing tools do not have their cutting edges on the centerline of the shaft, and consequently, they have some torque feedback to the user. He uses cross-shaped handles to give him a better grip with his fingers and thumb than he would get from the skin of his palm with a round handle.

Here is the angled hollowing tool in action. I find this tool scary, but he made it look easy.

It is not easy to measure the thickness of the shoulder with a traditional caliper. Enter the homemade "Jimmy Johnson" measuring device.

Here the "Jimmy Johnson" caliper has just been inserted, but it is not yet at the right angle for use. The measurement will be made with the tool rotated around so that it is parallel with the bed of the lathe.

Here is the partly hollowed form to be completed later. The tenon is left on for this reason.

For final hollowing to a thin shell, Paul uses a powerful light source with the light run through a shielded fiber-optic cable. This 150-Watt unit is from Fiberoptics Technology and has a custom light pipe. He holds the business end inside the hollow form along with his cutting tool. No mean feat. If you want one, Paul sells them.

To save time, here Paul switched to another piece that had been fully rough hollowed. When Paul turns out the lights, the party is not over -- it is just beginning. He judges the thickness and uniformity of the vessel wall by the intensity and color of the transmitted light. Since this varies from wood to wood, he will stop at the beginning and make a measurement with a caliper to relate the true thickness to the amount of light coming out. That done, he can continue hollowing to the end.

Because the piece is spinning, variations in transmission between end grain and side grain (if the piece is turned in the side-grain orientation) will average out. Care must be taken if the color of the wood changes as he moves deeper in the piece. When it looks like this, he knows he is done.

This is a typical result. (Sorry for the out-of-focus photo.) The walls are very thin and extremely uniform and smooth. Achieving this quality with a laser would be possible but dangerous, as that laser spot can move around a bit. Doing this with repeated hand measurements would be very difficult and time consuming. The light box isn't cheap, but it sure works.