Re: How fast is too fast on a Bridgeport?

Yea, its scary fast. I've slowed it down from my first encounter
with "shock and awe". Whoever designed the Position Wizard
aftermarket table on it must have had loads of fun and then slowed it
down in the original NC controller. I never saw it work (or any
other CNC machine for that matter) before designing a new controller
(with substantial assistance from the members of this group) and
testing it under MACH2.

Now that I know I can leap tall buildings in a single bound, I
welcome any advice about rational XY and Z axis speeds and
acceleration (I'm running microstep at 1000 steps per rev).

Incidently, if anyone is interested I have a control wiring diagram
posted in the photo section of the Master5 Yahoo group under Washcomp.
I have removed (but still shows in the drawing) the bypass
switch/relay contact in the limit switch section. I put it in to
force me to use both hands to start the machine, but it was too
awkward.

Thanks and regards,
Jeff

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Matt Shaver <mshaver@e...>
wrote:

> 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