I was trying to make two rings from copper pipes, 1.625" OD (wall thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively. The length of the ring was to be 0.75".
I cut the pipe oversize on my bandsaw. As expected the cut was not exactly square. I clamped the first ring initially on the inside in my3-jaw chuck trying to make sure that the sides of the piece were at right angles to the body of the chuck as determined by a square.
I faced off the first side and deburred it. I reversed the ring and clamped it the same way with the faced-off part flat against the jaws base. I faced off the other end to the required dimension. Everything looked good.
However, when I checked the final product with a square it was obvious that neither plane of the ring was square to the sides. I did an additional check with a height gauge with the ring on a flat (well, as flat as I could get) surface. There was a difference of 0.017" in height of the ring around the circumference.
I tried a second ring of the same diameter, this time clamping on the outside. I checked the position with the square in three different spots. The interesting part was that the fit was square in two of them but not in the third.
Anyway, the result was almost identical and I got the same result with the larger ring.
Although the result is adequate for my purposes I would like to know why I was unable to make the rings properly. Was I not following the correct procedure? Where in the procedure could the error have occurred? I have never before had a problem with facing-off being out of square with the sides.
Michael Koblic, Campbell River, BC