I installed the new gibs in the Clausing 5914 yesterday and today. The
difference is amazing. Worn and misshapen gibs appear to have been a
large part of the problem, and is why tightening the gibs didn't have
quite the expected effect.

Now I can trepan in forward rotation, without the drama, although there
is some squealing. In reverse rotation, turning very slowly (~90 rpm),
there is no problem making a 3/16" wide face groove in 6061 aluminum,
and there is no squealing. I went to 3/8" deep, and could have gone
deeper if the toolbit were better shaped. The chips are about 0.010"
thick by 3/16" wide. This, using a shop-made 1018 steel 0.75" diameter
coaxial boring bar held in a BXA-4D boring bar holder. Back gear is
needed, in both directions.

It's hard to really tell, but my theory is that the too-long 1/4-20 flat
head socket cap screws that protruded and rode on the top of the
cross-slide dovetail prevented the dovetail from fully seating, and
caused the gib to wear oddly, rendering the whole affair a bit springy.
The gib was too worn for this to be corrected without making it too thin
to work.

The compound slide dovetail was also not resting quite right. I did
find a flattened chip firmly stuck to the bottom dovetail, plus some
dings. I carefully scraped and file-dressed all mating surfaces to
eliminate everything sticking up, and then installed the new gib.
Again, the old one was quite worn, and also had been damaged by someone
adjusting the gibs with more muscle than brain, the corners being broken
off. One of the gib screws came to me pre-bent, presumably having been
damaged in this muscle-bound process. Replaced the bent screw.

Cleaned up and with the new gib, the compound now feels much better than
before, and doesn't have nearly as much looseness in the center of the
travel range as before.

It appears that Clausing makes the gibs from far softer cast iron than
that used in the dovetails, as almost all the wear was in the gibs.


For the record, I torqued the bolts holding the headstock to the bed
ways, and found them to be very tight, so motion between headstock and
bed seems unlikely.


More generally, I'm catching up on a whole lot of deferred maintenance.
I'm just now getting to the point that I can make things on the lathe,
versus having to work on the lathe itself.


For the record, I did some measuring of the new gibs. The taper is
exactly 5/32" per foot. The height is different in the two gibs, but
the taper is the same. The height is not critical, so long as it fills
most of the available space. It does not look hard to make new gibs if
one has a surface grinder.

The new gibs are 10-5/8" long, and one cuts them to length. This is
because Clausing cannot know how much the dovetail has worn, and so must
cover a range of possibilities.

Clean dovetail, assemble, insert gib, tap in deeper until it just stops
solidly, mark with scriber, cut the thick end off 1/16" in from the
scribe line, and the thin end 3/8" in from the scribe line. Dress with
a file. Clean, oil, install, and adjust.


Joe Gwinn