The holes in the tailstock where the split bushings sit
have some natural variation in diameter. If the holes are
slightly too small, the split bushings will still
fi
t, but the
1/4” plunger rod
will not
move smoothly. In that case,
plotting is simply not possible. Consequently, we try to
err on the side of “too large” in the hole diameter.
However, when the holes are slightly oversized, there’s a
new issue, which is that the plunger can wiggle a bit from
side to side. That can lead to a loss of precision in
plotting.
In practice, it’s much less of a problem than you might
think, because the plunger is operated under tension and
tends to stay put fairly well once you begin plotting.
None the less, it may be desirable to take out some or all
of the slack in the bushing position. We’ll show two
approaches: Shimming them with tape and gluing them in
place.
?
Appendix B: Improving plunger precision, part 1
