Re: GEM-500PCN bedmill - CNC ready

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