RE: [CAD_CAM_EDM_DRO] CNC Servo motor gear ratio: overheating. EMC step rate. Tablespeed

On Sun, 2003-06-08 at 13:07, Tim Goldstein wrote:
> Jon,
>
> We discussed these particular motors previously on this group. The
> consensus was that these motors were not a good selection for direct
> drive on most mills. The only specs that are on the Camtronics website
> are:
>
> These motors have a 5/8 diameter shaft 1.75L. The bodies are 4" diameter
> and 4.5" long. It has a standard 3.250 DBC on the front face. about 50
> oz in per amp torque and RPM is about 900. 36 VDC PM brush ball
> bearing.

OK so far.

> So at 25 rpm for his 5 ipm which I am assuming is a speed he plans to
> actually cut something at I think he will be risking getting very hot
> motors and potentially frying them.

We'll be cutting at this speed. 50 oz in per amp. Lets say we need 300
lbs force, which is 200 ish oz in torque or 4 amps. 4 amps x 36 volts =
144 watts. Is there some minimum speed that servo motors can run at or
some sort of derating of torque at low speed ?

I obviously need more info if there is.

> Tim
> [Denver, CO]
> Sherline products at Deep Discount
> Mach1 & DeskCNC with credit card ordering
> www.KTMarketing.com/Sherline
>
>
>
> > -----Original Message-----
> > Tim Goldstein wrote:
> >
> > Yes your motors will suffer major heating problems set up that way. If
> >
> > >you want to run at that low an RPM you need to use steppers.
> > >
> > I think not, as his expected load is 2.8% of the peak. These
> > are very large motors, and he doesn't expect cutting loads,
> > apparently.
> >
> > Jon
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
>
>
>
> Addresses:
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