Conference 44.392::eng_in_miniature

Had a look at my Myford over the weekend. Remember this is an S7 with power
cross-feed (which changes the saddle design somewhat).

The leadscrew guard is attached by two "slotted studs with lock nuts". These
appear to be gib strip adjusters for the half-nut dovetails, so that any time
you disturb them you will need to readjust them. There is a third adjuster below
these two, which does not have a secondary function.

I remember a quote from way back, which said that the art of the design engineer
is to ensure that everything has only one function, and can be
assembled/dismantled/adjusted without disturbing anything else. The art of the
production engineer is to ensure that every component serves at least two
functions, if not more, and can be assembled in the factory as cheaply as
possible. Looks like the production engineer won out here...

- Brian

<Had a look at my Myford over the weekend. Remember this is an S7 with power
<cross-feed (which changes the saddle design somewhat).

So is mine.

<The leadscrew guard is attached by two "slotted studs with lock nuts". These
<appear to be gib strip adjusters for the half-nut dovetails, so that any time
<you disturb them you will need to readjust them. There is a third adjuster below
<these two, which does not have a secondary function.

Yikes - My top hole has a slotted stud and lock not but the bottom hole
just has a bolt in it.  Anyway I have been removing and replacing these
a couple times a week and never adjusted one yet.

So what exactly is out of adjustment - that is what would the symptoms be?


Bye          --+--
Kay R. Fisher  |
---------------O---------------
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[sorry about the delay in replying - lots of travel at present]

The adjusters appear to be for the leadscrew halfnuts. I have not taken the
saddle off this machine, although I did on my old ML7. I believe that the half
nuts are fixed into castings running in dovetail slides in the front of the
saddle. The effect of poor fits of the slides would be to increase apparent
backlash in the leadscrew-saddle "fit". In other words, more slop than you get
through the thread clearances alone. In extreme cases, there might also be
problems in engaging the half-nuts. The thrust face of the half-nut slides for
normal screwcutting is also against this adjuster side.

To adjust these slides, I guess that you need to disconnect the normal operating
handle with its pins on the back of the boss which actuate the half nuts, and be
able to move the sliding parts by hand to feel the effects of adjustment. Sounds
to me like the preferred way is to remove the saddle - which sounds like an
awful lot of work! Not sure how easy it would be to move the slides without
removing the saddle, although it might be possible (if somewhat awkward for the
top slide).

- Brian