Joseph Gwinn fired this volley in news:joegwinn-
:

In article ,
Ignoramus25542 wrote:
....
If I try threading, the half nuts would not stay engaged, they lose
this engamenent in a second or so. If I hold the engagement lever,
they they do stay engaged, but I feel the lever kind of bumping.

What would be the typical cause of this?

Wear and/or maladjustment. How much backlash does the closed half-nut
have? (This ordinarily does not matter unless one is making very
accurate and long screw threads, but is used to gauge wear.)

Joe Gwinn


Iggy, odds are you'll find almost no thread at all in the half-nuts. As
they become severely worn, the will tend to "hop" out of engagement.
There's only one solution -- replace them; if you're really in a pinch,
you can re-make the parts, but I'd look for replacements first.

LLoyd