June 2018 meeting
Twenty-seven members attended the June meeting of HCT. Much of the meeting was taken up with discussions about the July symposium. It will be an exciting event with some vendors now committed to attend and over 70 people registered.
Earl reminded everyone to fill in their forms if they want to enter items into the Creative Art show at the Saskatoon Exhibition August 7-12. You can get more information and a copy of the form by clicking HERE.
Show and Tell was well represented with 9 members showing pieces. Here is a visual essay of the pieces.
Trent did a demo on how to use a small CCT camera hooked up to a TV to accurately turn inside a hollow vessel.
Through the magic of television the outline of the cutter drawn with the marker is visible on the screen when the cutter is inside the vessel. This allows you to ‘see’ inside the vessel while the camera shows the outside of the turning. You can watch the TV monitor and use your hand to advance the cutter.
For an alternative explanation of this demo check out Bob Baker’s write-up that he produced when I did this demo at the Sask. Woodworker’s Guild meeting. Thanks so much Bob for letting me use this.
“Turning while watching TV” by Trent Watts
Trent demonstrated one technique used for turning hollow forms, vessels where the inside is removed through an opening that is much smaller than the inside diameter of the vessel. Hollow turning requires blind access with your turning tools to the inside of the form.
Trent pointed out that the objective of hollow turning is to get uniform wall thickness, and that the challenges of hollow turning include judging the thickness of the wall and getting your tools to cut around sharp corners.
Hollowing tools consist of a high-speed steel or carbide scraper attached to a mild steel (less likely to break) shaft. Trent was using a shaft with a reverse S-curve to better reach the inside of the vessel through the small entry hole. Turning with a crooked shaft introduces yet another problem, that of high torque trying to twist the shaft. One might need an arm brace or some sort of mechanical device to counteract the torque. Rather than purchase a commercial cutter, Trent had made his own scraper/cutter out of a John Deere hay mower part.
Methods of assessing wall thickness include use of a caliper, a light inside the form, or, as in this demonstration, use of a camera and a TV monitor. Thus, “turning while watching TV”.
Starting with a form where the exterior has been turned to the desired shape, a 7/8 or 3/4 inch entry hole is drilled to the desired depth of the inside cavity. Trent used an arm designed by Elio Menis, the so-called “Elio arm”, to hold a small camera directly over the scraper. The camera was connected to a small TV monitor mounted just behind the work piece so that the Trent could view the work piece, the tool and the monitor.
With the tool outside of the work piece, Trent drew the outline of the scraper on the monitor with an erasable marker. He then added a line around that outline to mark the wall thickness.
Because the camera is always lined up with the scraper, the turner can use the outline on the TV monitor to “see” how close the scraper is to the inside wall.
I’m pretty sure the turner cannot rely totally on this intriguing technology. Trent was obviously using his experience in turning, his feel of the tool, and his hearing, to carefully remove most of the inside of his turned vessel. And he didn’t have his TV tuned into his favorite channel!
Thanks for another fascinating demo.
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