On 2010-02-04, Ignoramus25542 wrote:
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'.

Got something else going on...

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.

I can think a few possible causes:

1) A large chip embedded in the Acme thread of the leadscrew (or
the long key groove used to power the power feed in some
machines).

2) A bent leadscrew, bumping the half-nuts open.

3) Badly worn half-nut threads. (It is possible to
cast new ones in Babbit metal.)

4) Missing detent spring in the half-nuts lever assembly.

5) Is the interlock between the half-nut lever and the power
feed lever working properly? It should not be possible to
engage both at the same time. Each should lock out the other.

Good Luck,
DoN.

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