Reverse Chucking challenge...

[Arlan Ten Kley]

I've turned myself into a corner...!

I had an odd shaped piece of the dogwood that I started to turn as a bowl. I do not own a bandsaw so I often start with very irregular pieces. As I was roughing it out I saw an opportunity to create an un-natural edge hollow form.

I enjoyed hollowing through a somewhat invisible hole and it was very educational being able to see the cutting edge do its work through the blur. This spalted wood is not the strongest and this being my first "winged" hollowform, I took it down to only about 3/16". I dared go no thinner!

To maximize the size of the resulting piece, I have a relatively small (short) tenon. Now it is time to reverse the piece and finish the bottom....

I have been turning only small pieces, typically hollowforms and have used friction fit sacrificial tenons turned on a piece of scrap to finish my pieces. I do not own a Longsworth chuck nor a donut chuck. I realize that I will need something along these lines, and even then I imagine it will be a bit of a challenge to properly support the uneven piece. I guess I could also mount a larger piece of scrap on a faceplate and turn a mortise to the right size for the whole piece fit into. So...what should be my next fixture project? Are there better options I'm not considering?

Here are a few pictures to help visualize the situation. I appologize for the wierd looking background coloration....

[Brian McInturff]

If you have a vacuum chuck setup then make you a chuck just a little shy of the largest diameter. You can make the chuck as deep as need be but on this piece it can be normal.

[Brian McInturff]

Oh and if there is still a leak with the vacuum chuck then get a roll of shrink wrap and wrap the chuck and bowl together. The shrink wrap will prevent any leak.

[Steve Schlumpf]

Arlan - as small as the hollow form is I would just use a belt sander and remove the tenon.

[Bill Bolen]

You might also consider making a small friction chuck. Bascially a cylinder with one end to fit your 4 jaw chuck and the contact end slightly rounded. Cover that end with something like foamies from Wmart, bring up the tail stock and turn down to a very small tennon. Snap the tennon off and sand it smooth. That's the way I do the bottoms of NE bowls and is simple,effective and free!...Bill...

[Ken Fitzgerald]

For this I'd do what I used on my N/Es.

I have a donut chuck simply made from two pieces of scrap 1/2" plywood. I bought some 2" styrofoam insulation at the local Borg. I cut a couple of pieces of styroform insulation slightly smaller than the diameter of my donut chuck. Using double sided tape I tape the insulation to donut chuck and turn it to form a cone with a flat end on it. I mount the bowl on the styrofoam and then bolt on the other piece of the donut chuck to secure it. The bowl or n/e is then suspended on the insulation and the sides of the N/E arent' touching the base of the the donut chuck. I then turn away the tenon.

I hope this makes sense.

[Tim A. Mitchell]

Chuck up a dowel and put some nonslip type material as a pad on the end. Place the bowl on and bring the tailstock up. Light cuts should get most off of it.

[robert hainstock]

As has already been said, make a friction chuck out of scrap and sticky material. I use rubbermaid shelf liner glued to a dome shaped turned plug with a rounded surface. :) Bob

[Arlan Ten Kley]

Thanks for the thoughtful ideas. From my present perspective, the vacuum chuck is the ultimate and the belt sander a last resort! I may use some combination that utilizes the tailstock, but I really want to develop the capability to fully turn the bottom of this type of piece. I had not thought of using foam insulation in conjunction with a donut and can see all the potential there. That combination is probably within the present budget! I'm probably going to set it aside for a few weeks, as I will have minimal time in the shop due to work commitments. These ideas will give me the start to plan and source my fixture project when I can devote time there. Thanks everyone.

I just hate not being able to finish something though....!

[Jim Becker]

The simplest solution is a David Ellsworth type "jam chuck" technique where you put the piece between centers to finish the bottom off. As you get down to a tiny bit of material, you slow the lathe way down to just a few RPM and part it off with a slight undercut...or do that off the lathe with a sharp chisel or carving gouge.

[Curt Fuller]

Maybe turn a jam/friction type chuck with a mushroom shape that would fit through the side opening. That would give a larger surface against the inside. Then like Jim said, bring up the tail stock and lightly cut the tenon away and do what ever decorative base you like. Then a chisel and a little light sanding to remove the nub. Good luck. It's a nice looking piece. Be sure to show us the finished results.

[Allen Neighbors]

I like Curt's idea best. That's the way I would do it. :)

[Brian McInturff]

If you have a vacuum: make a small chuck that will fit inside the bowl. Then take a tailstock chuck adapter, mount the bowl, turn on the vacuum, remove tailstock and chuck. The tailstock chuck adapter is a godsend with a vacuum chuck. There are no worries about it not being on straight. I've just never really liked jam chucks. I find the vacuum chuck will get me exactly the same thing and is less likely to move or deflect. But it also could be that I never got the technique down good before I gave up and bought the vacuum.

And I totally forgot to mention that you have one NICE looking bowl there. You were able to envision what a real piece of art could be brought out of the blank. I bet you have one happy bog smile on your face. Just way way kool!!