Re: GEM-500PCN bedmill - CNC ready

Smoke,

Don't electric motors use grade 3? And grade 5 for supporting a
leadscrew seems ok... Certainly NOT for a spindle, but for the
leadscrew?

Ballendo (I'd be glad to "test" it)

--- In CAD_CAM_EDM_DRO@y..., "Smoke" <gordonr@r...> wrote:
> Ball bearings are classed as grade 1, 5 7 and 9. These grades
refer to
> Bearing tolerances with grade 9 having the most precise tolerances.
> Therfore using grade 5 bearings means low tolerance bearings are
being
> used...an indication of a low quality machine.
>
> Smoke
>
>
>
> >Jon,
> >
> >For this mill as configured with the Fagor control it is slow. I
> >don't know the price complete with Fagor, but if in 20 quantity
less
> >control etc it's $3750 ( I think that's what I read here) then it
> >must be at least $12K complete in single quantity. For that price
I
> >would expect much better performance, wouldn't you?
> >
> >I thought this machine had grade 5 ball screws, whatever that
means.
> >So speed limitations of Acme screws are not an issue here. Also, I
> >assume it has servos, I can't imagine any machines are still being
> >built with factory made controls and running steppers.
> >
> >At any rate the specs have errors and are very incomplete which
makes
> >me wonder about the builder.
> >
> >thanks,
> >
> >Doug
> >
> >
> >
> >--- In CAD_CAM_EDM_DRO@y..., Jon Elson <jmelson@a...> wrote:
> >> dougrasmussen@c... wrote:
> >>
> >> > Guys,
> >> >
> >> > I checked out the specs for the above mill. Errors in their
> >> > specifications!!!! As I mentioned several weeks ago, this may
be
> >a
> >> > clue as to the overall quality of a machine.
> >> >
> >> > They note the feedrate at 2000mm/rev for the CNC version. Do
they
> >> > mean 2000mm/min, which would translate to 79/min? 79 in/min is
> >> > painfully slow, if that's the correct value, why can this
machine
> >> > only go that fast?
> >>
> >> 79 IPM is painfully slow? Talking with Sherline owners with
> >Microkinetics
> >> drivers, they were getting 14 IPM rapid feed rates, and at least
> >some of
> >> them thought that was OK. With my stepper rate generator board I
> >got
> >> 25 - 30 IPM. On my servo-controlled Bridgeport mill I can go to
> >105 IPM,
> >> but I rarely take it over 45 IPM because I have a tendency to
cause
> >> catastrophic crashes.
> >>
> >> Now, for a real commercial shop, they want 400 IPM rapids, but
most
> >people
> >> discussing this and similar machines are not doing commercial
> >production.
> >> Going much faster than this may cause real problems with Acme
> >screws.
> >> Anyway, with steppers, the power decreases very fast with
> >increasing speed,
> >> so that may be the cause of the speed limit.
> >>
> >> Jon
> >
> >
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