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Steady Rest Rehab + a New Steady Rest Casting

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This is a steady rest I bought quite a while ago for $15 at a flea market. Back when I was building my new lathe, I tried to use it by adapting the base. But I eventually gave up on the steady rest as too much of a rehab project in itself, and shelved it for another day. Well that day has come around.

I'm not sure what lathe it was originally intended for. It  had a single prismatic slot on one side of the base and a flat on the other but I sawed off the base to fit the new lathe. It was, in my opinion, poorly made. The fingers were all unmachined castings with the draft taper left in place, making the tops wider than the bearing faces. The slots for the clamping screws weren't machined either. The slots weren't long enough to give full range of travel.

There was just some evidence of crude belt sanding of the fingers to fit their individual slots. They didn't all come together evenly or in the same plane. The base slots themselves were very roughly cast, and weren't machined. When I tried to mill them true, it turned out they were chilled iron, and I chewed  up a good end mill. Even a carbide mill wasn't up to the job. That's when I shelved the project. Here are some photos of what it looked like then, and some of the problems:

I did try milling the slots again today with a homemade insert mill, but got the same result -- some chilled iron too hard for carbide. That was the last resort before trying to anneal the whole works. I was a little concerned that a casting this large might crack if reheated and cooled again in the ashes of my wood stove. I'd done that trick before with small pieces, but nothing this big.

I decided to try my oil furnace instead. Since it's insulated with refractory blanket, I figured the cool-down period might be slow enough if I covered the openings after the heat. In order to slow the heat up period, of reduce the risk of cracking, I decided to remove my oil burner and substitute my atmospheric propane burner -- originally intended as a brazing torch. It could do a slower heat up, and without all the noise of a blower ....I figured it would be up to the job.

So I loaded the steady rest castings into the furnace, cranked up the propane pressure to 12 PSI, lit the torch and placed it in the tuyere. Pretty simple. I left it there cooking while I did some nearby cleaning and inspection of a new 4-jaw chuck (not a happy experience, btw). A half hour later the inside of the furnace and the pieces were glowing orange, so I shut down the burner.

The casting is not much more than 3/8" thick in any particular place, so this seemed enough time to heat soak. I placed a fire brick over the exhaust hole, pulled the burner out and plugged the tuyere, too.

Four hours later I felt the outside of the furnace and it was just slightly warm. Same for the lid. So I opened her up, and judged the temperature to be about 200F -- low enough to remove the castings. They looked good -- all the paint was burned off, except for some powdery residue. The metal looked good, and best of all, I could notch with a flie the thin edges of the finger slots on the casting. This meant it was machinable, finally. Quite happy with the result!

Glad to hear it worked!


Thanks Kjelle!  :beer: The furnace is becoming quite a handy tool for a lot of things.

Today I mounted the steady on my mill, did a lot of measuring and figuring where to cut to correct the problems and then just skimmed the slots to clean them up. It was the first machining they'd had since cast. I tested the fit with 3 pieces of 1/2" x 1" hot rolled steel -- it was a close sliding fit and the fingers came together nicely and in the same plane.


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