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Wednesday, December 24, 2008

Pitkin Donut Base and Clamp

Update: Well, I've been taken to task in the comments by Andy at Workshop Shed about being unclear as to the purpose of these parts, and he's right. They are a new base for the compound rest for my Jet 9x20 lathe, and a new four bolt clamp to match the new base. There, fixed.

In the previous post I mentioned what's being called the Pitkin Donut base on the Yahoo 9x20 lathe group. Mine is well underway, along with a four bolt clamp to match. The drawing shows what they will look like if all goes well and everything fits. I'll have some dimensions and photos of the parts being made later. The clamp is not absolutely necessary. The compound base as designed by Mr. Pitkin used four bolts and four independent clamps. I wanted a single four bolt clamp to hold mine down, just because. I had some problems with interference between the clamp and the rest of the compound rest, so I'm holding off on giving dimensions till I know I have things right and everything fits. Until then, enjoy the drawing.

Update: Things are coming along nicely. I still have to bevel the top of the clamp ring and drill a few holes in the base, but I'm almost done. The original two bolt clamp is at the top of the second photo. Obviously, the new mount is substantially heavier. I think I've also managed to build the new ring clamp so as not to interfere with any part of the upper half of the compound rest, and to make the bolts accessible regardless of it's position.
Last update
: The new base is finished. The third photo shows from left to right the original mounting base and two bolt clamp, what has become the standard four bolt clamp, and the Pitkin donut base and it's new four bolt clamp. The last photo shows the compound rest with the new base and clamp installed on the cross slide. It's important to say here that the bottom of the compound slide does not touch the bottom of the recess in the Pitkin base. The compound slide rests on and is supported by the three inch ring at the top of the base. That's where the added rigidity comes from. You can see this in the last photo, and that's why I included it. I'll end by saying that I made this base and ring out of 4140 annealed, which is considearably more difficult to machine than 1018, which is what I've been accustomed to using and what the first four bolt clamp is made of. 4140 is considerably harder on your tools and bits as well. It is stronger though, and strong is what I was after. I've also updated the first photo with dimensions. All lathes are different, use these dimensions at your own risk.


Andy from Workshopshed said...

The base looks interesting but what is it for?

Smitty said...

Well, I guess I haven't been clear. This base replaces the original base on the compound rest. I'll have more pictures later showing the compound rest with the new base and ring clamp in place.

Andy from Workshopshed said...

Ah yes it makes sense now, excellent results!

Eric B said...

Do you have the dimensions? I clicked on the drawing but did not see any.

Smitty said...

I'm working on a dimensioned drawing. I expect to be able to update the photo in a few days.