Wednesday, April 30, 2014

Step #9: Making the hold down bolt, nut and washer for steady rest

Here's something exciting. Once you reach this point you are very close to using the steady rest. I actually had to use it to fabricate the lead screws for the fingers. In order to use it I needed to jump over to fabricating the hold down bolt and the nut and washer to clamp it to the lathe bed.

The bolt is nothing more than a .25 diameter piece of stainless steel rod 2.25 inches long and threaded both ends with a 1/4 - 20 thread. The body is tapped correspondingly. Be sure not to drill all the way through the foot and break out the top.

The stainless steel nut is fabricated from a short piece of 7/8 diameter hex rod. This is important because there is not room beneath the bed rail to bring your cross slide in very close if you use a star knob on the steady rest. As you can see from the photo, the hex nut solution gives full clearance and is beefy, easy to manipulate, and you can crank it down with a wrench if you need to. The washer is just simple brass. I went one size number drill larger on the tap hole in the nut to make it really "spin" on fast since it's usually a blind operation being done by feel.

(I haven't included a drawing of the hold down bolt, nut and washer in the fabricated parts drawings in the kit. They are very simple to make and as long as it's long enough to clamp up nothing is terribly critical dimensionally and can be designed however you like).
Hold down bolt installed

fabricated Nut and washer

Spins on nicely
Hex nut leaves room for cross slide to be very close
Getting the center height right for your lathe is very important (though not micro-critically so because the fingers themselves adjust). I'm a stickler for this sort of thing myself so I left extra material on those brass wear strips I installed to be removed carefully at this point now that I can locate the center of the confluence of the fingers and test it using a center collet in the headstock.

There's enough material on the raw lower frame itself for this so you could forego the brass inserts and just machine or file the stainless/bronze part to fit at this point. Keep checking for flat, square and perpendicular as you go especially if you are filing versus using a mill for this operation. You'll have to reduce the angled walls of the foot too but go slowly or you'll get too loose a fit side to side.

For perfect alignment, leave it high and sneak up with a file

Check often for perfect perpendicular

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