Friday, February 14, 2014

Steady Rest, some more

I have been away in Anchorage for the last two weeks. Although I can post from there, the laptop I use drives me to distraction. Most of this is caused by the touchpad cursor; I suppose I could do something about that -- but the laptop also runs Ubuntu Linux, which I hate. Just me. I could fix all these things, but I don't feel it's worth the effort.

While I was in Anch I did some carving, a pleasant change from machine work. That's a future post. I would like to record progress on my steady rest.  All of it before I left for Anchorage.

I finished milling the dovetail slides and for improvised cutting setup it was a very good fit. I was pleased. I will have to drill and tap some holes for fixing screws, but that comes later.

 Next picture: the body of the steady. It will be screwed to the dovetailed piece.This is just drill and tap. I will not show it.
Now comes the really crucial step. I must put a great big hole (25mm) in the vertical plate. The center of the hole must be exactly at center height on the lathe. Once  you get the hole drilled, the center is gone! So I put a sharp point in the lathe chuck, and located the centerpoint by tapping the work with a hammer. That is center height. (The nominal height is 2.5" or about 62mm, but it is not advisable to rely on this.). we have a centerpunch mark. Right where it belongs.
So we can drill a pilot hole on the punch mark.  Now if I could chuck this in the lathe I'd be in clover. I could bore it out with a boring bar. But the upright will not "swing" in the lathe. Obviously -- it is at center height. So we will have to mill it out. The big boys do this on a rotary table. I have no such animal. It costs almost as much as the mill! So instead I built a fixture.
 Somewhere on my walks I found a very heavy piece of steel; whence it comes I know not. But I drilled my work something like 6mm and also my fixture, more or less in the middle. I pushed the work on to the pin. Then I could rotate the work around the pin, with my hand. So the cutter cuts a circle. Keep increasing the Z axis till you go through. This is definitely the pauper's rotary table! But it works. As Tom Lipton says, "we're all heroes in Aluminum".
After this, all that remains is to screw the upright back on, drill and tap the fixing screws, and make the fingers. 
Bought some aluminum to make the fingers. Haven't done a thing yet; busy carving. At least next post will be a relief from all this machining.We'll be doing some carving in wood for a change.

No comments:

Post a Comment