RE: Hey Tim!

> -----Original Message-----
> From: Matt Shaver [mailto:mshaver@...]
> Sent: Thursday, August 12, 1999 6:21 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Hey Tim!
>
>
> From: "Matt Shaver" <mshaver@...>
>
> > From: "Tim Goldstein" <timg@...>
> >
> > Matt,
> >
> > I didn't have this, but I do now!! Ask and you shall receive.
> >
> > Go to http://www.ktmarketing.com/CNC.html and it is the link labeled
> > "Calculate Steps/In for setting up your stepper software" which
> you'll find
> > as the last entry in the upper block of links.
>
> I would swear I saw this somewhere on your site, or maybe you
> have some other
> calculator type page? Anyway, Thanks!
>
> > Let me know if it causes any problems.
>
> Actually, I got a question via e-mail about what value to use if
> you have 5mm
> pitch leadscrews like some of the Asian machines have and I
> wasn't sure what
> value was wanted (steps/inch), or even whether it went in INPUT_SCALE, or
> OUTPUT_SCALE. Your calculator accepted 5.08 TPI with no problem.

The page you are remembering was to calculate the CYCLE_TIME value for EMC
based upon the steps/in and the MAX_VELOCITY. I have removed it from the
links on my site as Fred now has EMC figuring this value for you behind the
scenes.

The value you get from the new calculator page is really steps/unit. If you
put in the lead screw value you want as lead screw turns per desired unit of
travel the page will spit out the INPUT_SCALE value you need which is just
the steps/unit. Meaning, if you put in the turns per inch of table travel
you will get back the steps required to do that. If you put in the turns per
millimeter you get back steps per millimeter and yes, decimal numbers will
work just fine as you discovered.

> > Does this mean that you just about have a stepper setup running
> on EMC????
>
> I'm slowly getting my Bridgeport BOSS4 conversion done. I assembled the
> Camtronics 5A stepper driver board and hooked it up to the
> original BP motors
> and they work! It's a little hard to keep the acceleration rate
> slow enough
> using the onboard pulse generator to avoid phasing out the motor.
> I will say
> that raising the power supply voltage increases the maximum
> acceleration rate
> considerably. There seem to be certain RPM ranges where the
> motors are more
> sensitive to the pulse rate change. I am doing this on the bench at the
> moment, so there aren't any mechanical loads on the motors and I'm hoping
> that once the motors are loaded that the added inertia of the system will
> help reduce this effect.

---SNIP----

I have notice that the larger stepper motors seem to have certain
frequencies at which they are sensitive to acceleration rates and if you
keep them at these frequencies they are susceptible to loosing steps. It
seem the faster the acceleration you can get away with the better.

Sorry to hear about the transformer. Better it smoked now then when you were
cutting something important.


Tim
[Denver, CO]