Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: tom@sysabend.org on February 11, 2025, 02:28:54 PM

Title: Mach3 issue with RPM scaling ( I think ).
Post by: tom@sysabend.org on February 11, 2025, 02:28:54 PM

I've recently converted my CNC from a Huanyang VFD+Spindle ( RS485 ) to a 0-10v controlled spindle.

I'm using Mach3 with a Smoothstepper USS and C11G v8.2 interface.

After much re-learning and updating ( this CNC has been running since 2009 or so without being touched much ) I have finally gotten the Smoothstepper and Mach3 speaking to each other ( per latest USS suggested configuration ) and I'm getting the proper pulse train on Pin 14 however it seems to be off by 2 orders of magnitude.

In motor tuning I have it set for 1000 Steps per Unit and 1500 Steps per Minute.  This gives me the proper 25khz at "full speed". 
I have Spindle one set up for Minimum 0 Maximum 12000 Ratio 1.

If I turn the spindle on, 10rpm = 1v 6rpm = 5v and 120rpm = 10v and anything over 120rpm stays 10v.

This seems like its just a simple scaling issue but if so I'm having no luck finding it.  Any changes I make to motor tuning and I no longer get the proper frequency on Pin 14.

Hopefully this is simple and someone has an idea?

Thanks!

  -Tom

Title: Re: Mach3 issue with RPM scaling ( I think ).
Post by: JohnHaine on February 12, 2025, 03:24:51 AM

I think you need to configure pwm not steps/unit! And unless the ss has suitable pulse smoothing built in you will need at least an rc filter and an op amp to generate 0 - 10v from the pwm output.

Title: Re: Mach3 issue with RPM scaling ( I think ).
Post by: tom@sysabend.org on February 12, 2025, 11:21:09 AM

No, the C11G v8.2 interface is quite specific in that it takes a pulse train and not PWM.  I went down that road already.  Whatever is causing my issue *also* affects PWM however.  Max pulse width is hit by 120rpm.

Title: Re: Mach3 issue with RPM scaling ( I think ).
Post by: Graham Waterworth on February 13, 2025, 06:46:06 AM

I would check out this page :-

https://cnc4pc.com/blog/post/manual-configuration-for-a-c11g-on-mach3-with-the-ethernet-smooth-stepper (https://cnc4pc.com/blog/post/manual-configuration-for-a-c11g-on-mach3-with-the-ethernet-smooth-stepper)

Title: Re: Mach3 issue with RPM scaling ( I think ).
Post by: tom@sysabend.org on February 13, 2025, 10:48:45 AM

I had already read the specific manual section for setting up the smooth stepper.  It didn't help.

I did however find my problem.

I still had an old linearity.dat file from my prior VFD.

Removed that and my scaling issue went away.