08/17/00
Today I made the frames (plates) and the upper and lower pillars (posts). The frames are made of 1/4" x 1/2" leaded brass. Holes in both ends were first drilled undersize and then reamed to 1/4". First holes were drilled through one end of both pieces at the same time, with both pieces clamped together. Then the pieces were reversed end-to-end and the existing hole was used as a pattern to drill the remaining hole in the frame ends. That way, the holes in the frames exactly match. Pegs of brass were made to slip in both holes. These pegs will serve to keep the two frames exactly aligned with each other during subsequent operations.
The pillars were cut from 3/8" leaded brass. They were first marked out, then 1/4" spiggots were cut on all four ends. Then the ends were drilled and tapped at size 6-32. The threads were cut using a tap guide in the old South Bend lathe. The threads were cut with hand power, using the lathe chuck hold the pillar and the guide being inserted in the tailstock. The tap guide permits holding the tap in a straight line with the work, providing stability. This to make straight threads with less chance of tap breakage.
The pillars were tapered in the Unimat, using the compound rest set an an angle of 5 degrees. (Forgot to get a picture of that.)
Today's links:
Frame peg.
Pillars marked out.
Using tap guide.
Pillar finished.
Frames with pillars.