Hello Guest it is August 10, 2020, 09:07:12 PM

Author Topic: Options for DC Motor RPM Control  (Read 3872 times)

0 Members and 1 Guest are viewing this topic.

Offline kolias

*
  •  1,011 1,011
    • View Profile
Options for DC Motor RPM Control
« on: June 17, 2012, 09:34:36 PM »
For my new cnc I was thinking to get the Hitachi X200 or WJ200 VFD along with a Chinese spindle but the cost of getting the VFD working in my garage is too high. I only have 120VAC /15A available and the X200 needs 220VAC and the WJ200 needs 120VAC /20A.. Running new lines and sub panels in my garage is too expensive for me right now.

So I’m thinking to get the Wolfgang TB 650 spindle with the 12VDC motor, 200 watts, 25K RPM. But I want to control the speed and the Super PID controller is too expensive. Then I noticed in the CNCZone forum that Henrik says “Out of the box Mach3 offers On/Off, PWM and step and direction control of the spindle”

So does this mean that Mach3 will be able to control the RPM of my 12VDC motor without anything else?
Nicolas
Re: Options for DC Motor RPM Control
« Reply #1 on: June 17, 2012, 11:51:32 PM »
Hi,

You may be going about this the wrong way.

You need to determine what type of spindle you need.  Price is not what you use to choose the type of spindle. Price is used to choose within the range of a particular type.

A High Speed 2400W Chinese spindle is a completely different beast from a 200W DC spindle.  The Wolfgang TB 650 spindle is basically a PCB  or engraving style milling spindle.

What type of milling are you planning to do, wood, engraving, etc? These two spindle would normally suit different sizes of machines.

The wolfgang 12V spindle has no speed controller. It connects directly to 12V.

Mach produces a PWM control signal that is proportional to the requested speed as a ratio of the maximum speed. This control signal need to be processed and interfaced into s speed controller.

For a VFD, you could use a DC-03V3 Digispeed to accomplish this.
http://www.homanndesigns.com/store/index.php?main_page=product_info&cPath=1&products_id=21

I'm not aware of a 12V motor controller that accepts a PWM control voltage.

Cheers,

Peter.





----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline kolias

*
  •  1,011 1,011
    • View Profile
Re: Options for DC Motor RPM Control
« Reply #2 on: June 18, 2012, 09:51:22 AM »
Thank you Peter for the info and I’m sorry I was not clear enough

My cnc is a hobby machine planning to do light aluminum milling. My previous cnc had a Bosch Colt 1HP router and although I didn’t do any aluminum work I felt it was powerful enough for my needs and so now I was thinking a smaller spindle may be sufficient. I mean instead of taking a deep pass with a 2400W spindle perhaps I can do the same with a smaller spindle and make a few passes and at lower feed rates.

Cost wise, a large spindle is not that much more expensive than a smaller spindle but if I add the extra electrical work needed in my garage to get the right current available then the cost increases too much. I like the TB 650 except for the 1/8” collet which I find too small

Electrical work is not my strong field; so you are saying that with the DC-03V3 and Mach3 I will be able to control the RPM on the TB 650?

BTW I got the G540 and searching on the net for wiring schematics I found yours. A beautiful work

Nicolas

Offline kolias

*
  •  1,011 1,011
    • View Profile
Re: Options for DC Motor RPM Control
« Reply #3 on: June 18, 2012, 08:00:03 PM »
Never used anything more than a router before and so my knowledge is zero when we talk about VFD’s and motor controls.

But reading on the Net I understand that to control the RPM on a DC motor, first I need something like that
http://store.qkits.com/moreinfo.cfm/MXA087
and then if I want to interface with Mach3 I can use the Digispeed or similar.

But if I don’t mind to control the RPM manually from my control panel, a motor controller is all that I need

Perhaps someone can correct me if I’m wrong
Nicolas