First turning in new shop!

[Thomas Wilson80]

First off, thanks to Dave for putting these detailed directions on turning spheres (https://sawmillcreek.org/showthread....part-1-Preface).

I was moving last year and have been trying to get my shop up and running when Dave first put out his process and have been waiting to try this and finally got there this week.

Here is a sphere (about 2.5") from a cherry branch I've had for a couple years (has a few checks at the pith but I figured it would be great to start with). Overall, it was much easier and turned out better than I expected for my first go. I used a rubber stopper drilled out and screwed onto my live center but you'll notice there are tiny holes in a couple places from where the point of my live center pushed through the rubber stopper! I found that if I didn't tighten it well then I got some wobble - anyone have any guidance on how to hold the sphere on the tailstock end? I don't have any thread chasers and was hoping to find a simpler method. Maybe there are live MT2 adapters that would fit a second chuck mounted in the tailstock or an adapter that would fit the threaded end of my live center but I was hoping for a cheaper/simpler alternative.

Any input/comments/critiques are welcome.
Tom

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[John K Jordan]

Spheres are great practice!

I have various things for holding spheres. One is a piece of wood tapped to fit the threads on the (Oneway style) live center then cupped to hold the sphere. To turn the cup shape I mount the live center in the headstock and put a piece of soft iron wire through the holes to keep it from turning, making it into a drive center. Thread the tapped block on the live center and turn. I occasionally use this method to make small jam chucks for special purposes.

Another way is to use pieces from Rubber Chucky, one that threads onto a mandrel to drive and another that threads onto the live center. The pieces are flexible rubber and can be turned to shape as needed. I have these and use them but I usually just use the ones I made from wood.

Note that you can knock out the live center point with a small diameter knockout bar, good for a variety of applications.

BTW I don’t like the idea of a heavy scroll chuck on the tailstock because of the torque from bringing it up to speed, maybe ok if speed is changed very slowly.

JKJ

First off, thanks to Dave for putting these detailed directions on turning spheres (https://sawmillcreek.org/showthread....part-1-Preface).

I was moving last year and have been trying to get my shop up and running when Dave first put out his process and have been waiting to try this and finally got there this week.

Here is a sphere (about 2.5") from a cherry branch I've had for a couple years (has a few checks at the pith but I figured it would be great to start with). Overall, it was much easier and turned out better than I expected for my first go. I used a rubber stopper drilled out and screwed onto my live center but you'll notice there are tiny holes in a couple places from where the point of my live center pushed through the rubber stopper! I found that if I didn't tighten it well then I got some wobble - anyone have any guidance on how to hold the sphere on the tailstock end? I don't have any thread chasers and was hoping to find a simpler method. Maybe there are live MT2 adapters that would fit a second chuck mounted in the tailstock or an adapter that would fit the threaded end of my live center but I was hoping for a cheaper/simpler alternative.

Any input/comments/critiques are welcome.
Tom

IMG_6480.jpgIMG_6475.jpgIMG_6477.jpg

[Steve Eure]

Try this link.
https://www.rubberchucky.com/store/c...HUCKIES.html#/

This company makes some nice products, I have used several of their other products with great results, but not the sphere turning ones. I made my own out of hardwood that I can mount on a chuck mounted to a live tailstock center. I also made one with a 3/4 nut embedded in the wood that can be mounter straight to the live center.

[Thomas Wilson80]

Thanks Steve and John. I think I'll try the 3/4 nut embedded in wood and if I need something better, the rubber chucky would be perfect.

Tom

[Dave Mount]

Hey Tom, well done! Glad to hear I put a bug in your ear.

If I were trying to do this with just a standard cone-shaped live center, I'd do a more advanced version of something I tried early on. My initial device for the tail stock side is shown below. It was just a wood piece turned with a cup to contact the sphere and a bore in the back to go over the cone center (pay no attention to the step in the cone, that was something I did to hold another project).

Capture 175.JPGCapture 176.JPG

I was able to turn spheres with this, but it wasn't great, because of the narrow contact between the wood and the cone center. I moved on to a threaded live tailstock (like this one: https://www.pennstateind.com/store/LTCA18.html) which allows you to use a threaded block, a chuck, or a faceplate. But if I had wanted to avoid that expenditure, my next move would have been to refine the above approach. I made a sketch of what v2.0 would have looked like:

Capture 174.JPG

Same idea, but I would have made it so there were two rings of contact between the cone center and the wood block, so it couldn't slide around. My idea would be to drill two counterbores in the wood block, one small one to house the tip of the live center so you don't have to fit that, and a second larger one. I'd then chamfer the faces of the two steps so that they met the cone center at the same time. Not having done this, I think you could do it by cutting the larger ring back until the live center was resting on the inner contact point and was loose at the outer, then iteratively trim the inner contact point until they nest securely. This two contact approach should eliminate the problem I had with the wood pivoting around while I tightened the tailstock.

One other feature I might build in is to leave a spot on the outside of your wood block to put it back in a chuck to true it up. You can see a step like that in the one pictured above. To get really accurate spheres, it's best to be able to true up your compression chucks as they move through the seasons.

If you decide to take the plunge and get a threaded live center, order a small cheap faceplate at the same time and you can just screw your wood block to that. Alternatively, I have a 1" x 8 tpi tap, I could thread a few blocks and mail them to you.

Have fun with it! It can be a slippery slope, watch yourself! (or don't resist and slide on down, I'll meet you there).

Best,

Dave

[John K Jordan]

I didn’t get time to review what Dave wrote so he may have covered this, but instead of embedding a nut into wood to fasten to the live center you can simply tap the threads in the woods. I forget the tap size for the Oneway center and clones (Jet, PM, etc) but it might be 3/4x16. I found a tap in my drawer but a new one is not expensive. It’s best to use a bottom tap but a bit of the end of a std tap can be ground off if necessary. For me, the advantage of tapping the threads in wood is the flexibility and the speed - just drill a hole, tap, shape, and use. Note the threads don’t need to hold very securely since the wood will always be under compression. I tap into end grain - if you want cleaner threads just drill, soak with a bit of CA, then tap.

…. I think I'll try the 3/4 nut embedded in wood and if I need something better, the rubber chucky would be perfect.

Tom