Re: [CAD_CAM_EDM_DRO] Super Nuts

In a message dated 03-Nov-00 09:51:57 Central Standard Time,
jvicars@... writes:

<< What are the disadvantages of using the BSA Supernuts to do a
bridgeport conversion? >>

Joe: I have built several machines with BSA ACME screws with their Supernuts
(spring-preloaded "double half-nut" thingies), and they are fine IF you can
tolerate a good steady FRICTION in rotation, and, if you aren't counting on
the lead-screw to retain its dimensional integrity for more than a
couple-hundred or a thousand (at most!) operating-hours! The glass-fiber
filled Turcite works on a lead-screw kinda like epoxy-filled Scotch-Brite! I
have a home-brew CNC lathe I built in '84, controlled by a long-discontinued
CBM PET computer, and the longitudinal screw (303 SS ACME) has such worn
threads in the area most-used (95% of the time), one can SEE the threads,
there, are "thinner"! And one can HEAR the steppers "load up" as the
carriage is moved into the region where the screw sees use only maybe 5% of
the time! Ball-screws are the way to go, but require several prerequisites:
Money, patience, knowledge of use, EFFICIENT thread-wiper means, etc., etc...

Also, BSA's rolled screws, though quite fine, are not really "spec'ed" for
machine-tool lead-screw use. Accumulative tolerance per-inch, etc.

But if you are just doing some repetitive stuff where actual "miked"
dimension is not required to be down into the low-millionths, then a
home-brew with BSA ACME and Turcite preload nuts would probably do just fine.


But don't take MY word for it! I am just an ignernt old troll, never so much
as did "High School machine-shop". I just watched and copied and
self-taught, and now I tinker in my back-yard shop, to keep out of trouble
with CPS, etc.

Lotsa luck and fun! Jan R.