Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Jimmy B. Goode on August 04, 2010, 09:36:13 PM

Title: PWM and routers?
Post by: Jimmy B. Goode on August 04, 2010, 09:36:13 PM

Hi,
Does PWM work for adjusting the speed of router motors? That would be awfully convenient, so obviously it probably won't. I thought about just trying it, but I'm worried about ruining the router. I'd appreciate any info.

Thanks,
Jimmy

Title: Re: PWM and routers?
Post by: BR549 on August 04, 2010, 11:37:35 PM

Yes IF you have a motor speed controller that can use PWM   OR  analog+/- with a control interface card.

Title: Re: PWM and routers?
Post by: Tweakie.CNC on August 05, 2010, 02:17:09 AM

Jimmy,

PWM speed control works really well with 3 phase motors and their associated controllers but you run into problems with brushed motors overheating if they are slowed too much for too long (they all seem to have internal fans for cooling the windings). This doesn't mean to say that it can't be done though, just be aware of any temp rise in the motor.  ;)

Tweakie.

Title: Re: PWM and routers?
Post by: Jimmy B. Goode on August 05, 2010, 06:44:00 AM

Thanks for the info, I suspected something such might be the case.

Jimmy

Title: Re: PWM and routers?
Post by: ger21 on August 05, 2010, 07:55:38 AM

I think CNC4PC makes a PWM speed control that will work with a router motor.

Title: Re: PWM and routers?
Post by: Jimmy B. Goode on August 05, 2010, 09:44:28 AM

Are you referring to their C-19 frequency converter? I've been curious about this product. Has anyone used this device, and if so how did it work?

Title: Re: PWM and routers?
Post by: EzCyclone on August 05, 2010, 11:30:38 AM

I have the C19 in my control box and love it.  It's a great little device and will easily run a PC 690 or even a bit bigger spindle.  It's worth every bit of the price!

Title: Re: PWM and routers?
Post by: ger21 on August 05, 2010, 11:44:33 AM

C19 or C29. Don't have any experience with either of them, though.

Title: Re: Unwanted circles added to G Code
Post by: aqmsreme on August 20, 2010, 10:36:22 AM

I have been using the free downlaoded Mach III on my CNC Router. If I load my own G Code many circles are shown on the toolpath unless I have run the Write wizard first. If I then load my own G code after this they run perfectly.

I have now purchased a licensed version and to me dismay the circles are still added to my G code.

Has anybody else seen this problem and has anyone an explanation or cure?

Title: Re: PWM and routers?
Post by: Tweakie.CNC on August 20, 2010, 10:46:13 AM

If you toggle the IJ mode setting to Inc (config / general config) that should do it.

Tweakie.

Title: Re: PWM and routers?
Post by: aqmsreme on August 21, 2010, 10:23:11 AM

Thanks for that tip, however the IJ mode was already set to Inc, I decided to try setting it to Absolute and this solved the problem immediately and all is well without having to run a wizard first.

I will re-read the Machmill manual to try to understand what is going on

aqmsreme

Title: Re: PWM and routers?
Post by: ger21 on August 21, 2010, 01:06:36 PM

Quote from: aqmsreme on August 21, 2010, 10:23:11 AM

I will re-read the Machmill manual to try to understand what is going on

A lot of the wizards use absolute mode, so when you run a wizard, they changed the IJ mode to absolute, which is apparently what you're using as well. But since you had Mach3 set to incremental, it would revert back whenever you closed and restarted Mach3.

One way to make sure this never happens is to place a G90.1 at the start of your code, which will automatically put Mach3 into Absolute IJ for your code.