Reverse Chucking Conundrum

[Dennis J Gooding]

Dennis, that is one idea I was considering, using my large Cole Jaws as a platform. I thought that if I did that, I'd have to make some sort of soft-ish platform for it to sit against. Maybe Funky-Foam or something like that. My concern was that I might limit my ability to measure the thickness as I got near the bottom. However, If the vacuum/jam chuck approach doesn't work, this might be the best way to go.

Dennis, that is one idea I was considering, using my large Cole Jaws as a platform. I thought that if I did that, I'd have to make some sort of soft-ish platform for it to sit against. Maybe Funky-Foam or something like that. My concern was that I might limit my ability to measure the thickness as I got near the bottom. However, If the vacuum/jam chuck approach doesn't work, this might be the best way to go.

 

[Dennis J Gooding]

Brent, I would not tinker with using Cole jaws as the base for this, when a piece of plywood is cheap and far more adaptable. Advantages of the basic method include: The workpiece can be can be mounted and remounted quickly without any loss of registration. It will work on porous woods and work pieces that are out of round or have uneven rims, If you look at the picture in my original posting you will see a pair of holes in the disk. these allow bottom thickness to measured using calipers without dismounting the work piece. Once you have cut few registration strips and hold-down strips from quarter inch plywood., the initial mounting process usually takes only takes a few minutes using a screw gun.

 

[Brent Sobotka]

This was a challenging piece. I didn't want to get into the details previously. But the reasons I did things the way I did was because I wanted a very thin bottom with the intent of it acting somewhat like a soundboard of a guitar. I think this Cole jaw approach worked very well. In fact it worked better than I anticipated. It was solid, stable, and remained concentric throughout the turning. The only thing I did differently that I haven't shown is that I took foam ear plugs and put over the ends of the rods that held the clamps. That added a bit of visibility and padding in case I bumped it. However, I was very conscious of them the entire time and very careful, so that wasn't a problem.

I think that the bottom would have come apart with any of the conventional holding methodologies. The bottom is very thin. I'm convinced that that the side clamping technique was the correct answer. And in my opinion, the Cole jaws worked perfectly, and safely. I'll keep the technique in my back pocket for future projects.

 

[Peter White]

Well worth the effort you put into this.