Re: [CAD_CAM_EDM_DRO] How fast is too fast on a Bridgeport?

On Friday 23 May 2003 10:36, Peter R wrote:

> Hi Jeff,
>
> Are you sure the table really is moving at 1200ipm? Assuming you have
> your steppers direct coupled and are using 5 turn per inch ball screws
> i.e. 0.2" per rev then 20ips=1200ipm=1200/0.2=6000RPM - this is pretty
> darn speedy for any steppers I've ever heard of on this planet -
> particularly in the NEMA42 size. Keeping in mind steppers lose power at
> speed, I seriously doubt you are spinning your steppers at 6000RPM.
> Double check your calculations.

It's twice as bad as that since, if it's a stock CNC BP, the motors are belted
to the screws at 2:1. That would mean 12,000 RPM...

> I have a BP clone with NEMA42 servos and am quite happy with rapids in
> the 100-120ipm range.

The stock stepper Bridgeports did either 120ipm, or 150ipm rapid rates
depending on the model. Servo Bridgeports would rapid at 200ipm, but I've got
them up to 240ipm with a retrofit control.

Matt