Re: Rolled vs. Ground ballscrews or other screws!

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lance Hopper"
<snaggletto@c...> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
> <dave_mucha@y...> wrote:
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lance Hopper"
> > <snaggletto@c...> wrote:
> > > I've run a Bridgeport with ballscrews for a couple years. It was
> a
> > > beautiful experience in all situations. Climb milling is
> possible
> > > with smaller cutters and lighter cuts, but any backlash or slop
> will
> > > be violently taken up if the cutter digs in. Save climb milling
> with
> > > 2" face mills and heavier cuts for the machining centers. I
> don't
> > > doubt that anything is impossible, but to throw the table off of
> the
> > > machine means that the operator is a dumba** and has no sense
> > > or 'feel' for how to machine.
> > >
> >
> > I figure it this way, he has been a repairman for over 20 years in
> the
> > phila area for Bridgeport, so has seen more machines and been in
> more
> > shops than most tool salesmen.
> >
> > 2 over that time is not too bad as I have personally met more than 2
> > dumba**'s in shops running machines myself.
> >
> > But as we know a ball screw nut will run it self the length of the
> > screw if the screw is standing vertical. an ACME won't do that.
> the
> > ball screw also does not have the same TPI so it offers MUCH less
> > resistance when smacked.
> >
> > Dave
>
> Dave,
> I don't disagree, and my post wasn't aimed at you personally, or
> saying that the repairman was a liar. Ballscrews do have much less
> resistance, and thus very efficient with little backlash, that's why
> they are used. As you said yourself, in a period of 20+ years, the
> repairman has seen it happen twice. This is the exception rather
> than the norm. I would bet that if we had the details of 'how' it
> happened on those 2 occasions, we would see that the machine operator
> was doing something inappropriate for the job/machine. My point,
> ballscrews on a manual machine is not a bad thing.

I would fully accept that ONLY twice in 20 years is a very rare
occurance. probably a novice who ran the rapid the wrong way at the
wrong time with the cutter perfectly aligned for the disaster.

But, I sorta assume that there are people on here who are also
novices. : )

Knowing the potential exists gives fair warning. I would not
re-design a machine or do anything differently. but hopefully that
warning will have the guys drop the table to get the tool bit to the
other side.

Dave