Elementary Lathe Machining question

How square? Depending on the accuracy of your chuck, you should be able to get them within a thousanth or better for a cube of a few inches on a side.

Jim

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Chuck the 2 parallel sides between 2 jaws and bring the other jaws down into light contact with the (unmachined) sides of the workpiece. Face off the exposed side, reverse in the 4 jaw and face again. Now you have 4 faced surfaces; the 2 original surfaces and the 2 you just created. Place the workpiece in the 4 jaw again and clamp on the 4 faced surfaces and machine first 1 and then the other of the remaining 2 surfaces.

To obtain a cube, proceed again as above, facing off the amounts required to render a cube of the desired size.

Some will say this is easier to do with a milling machine or a shaper.

Bob Swinney

James Flanagan wrote in news:MPG.1aa6868e3236f342989689@news:

Good advice from the others. BTW, if you want to center the piece up in the jaws, you can mount an indicator on your cross-slide. Run it in till it touches off on one side, roll the spindle slightly back and forth until you find the lowest reading. Move the long slide out to clear the work, rotate the chuck 180°, move the long slide back in. You should have the same reading on both sides for it to be centered. If starting with square stock, you should get the same reading on all 4 sides (for drilling a centered hole or what not.)

Another trick to add to this is to take a piece of stock about a half inch in dimension and cut it to a length that it can be used between your lathe ways and the outer tip of the chuck jaws to act as a temporary stop for the chuck during indicating after rough-in. This will insure relatively equal positioning of the chuck for each pass of the indicator. Try to get the length of the stock to allow the jaw to be 90 degrees from it in use. This method also works reasonably well to scribe the OD of stock in a linear fashion with either three or four spacings with the tip of a tool bit, or to scribe three or four equally spaced lines in a radial fashion on the face of a turning with the cross slide. By scoring a circle on the face, along with radial lines, further lines can be developed by using wing dividers at the line intersections. These can then be scored by using an adjustable length stop to target the layouts for scribing with the toolbit. It's not a rotary table, but it can work for a lot of uses, depending on the imagination of the operator.

RJ