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Connecting EMC to an existing mill

Posted by Leav 
Connecting EMC to an existing mill
October 19, 2008 10:11AM
Hi Guys,

Sort of off the RepRap topic, but maybe someone here can help me.

My robotics team has a mini-lathe and a mini-mill, both of which are fitted for CNC (they have stepper motors).

I could not understand how the EMC software connects to a machine.
Is it through a serial port?

I gather that there is need for a stepper driver card to be present on the machine. is this usually the case?

I'm trying to understand if it will be possible to control these machines with EMC, but I cannot figure out what I need to check for or do.

Quite frustrating.. :/

Re: Connecting EMC to an existing mill -- Parallel port, I *think*
October 19, 2008 01:33PM
Leav, et al,

It's been awhile since I looked at this, but I think the most common way for an EMC system to connect to stepper motors was via a parallel port -- using two bits per motor, to drive step and direction on various stepper driver modues, much like the reprap arduino uses to drive the stepper controllers. If that's so (don't take my word/memory -- check the EMC site), you'd need a parallel port on the PC, and one stepper driver channel per motor -- *provided* that the stepper driver has sufficient current handling for the motors on you machines. Note that you could share the port and/or stepper drivers between the mill and lathe, if you were OK with only using one at a time.

Of course, you could also use an arduino or sanguino as an intermediary (between a PC without a parallel port and the stepper drivers), and not require the EMC software at all.

I'm curious, which mini-mill and mini-lathe does your team have?


Re: Connecting EMC to an existing mill
October 19, 2008 06:49PM
Hi Larry,

Not entirely sure what we have (they will check the model and manufacturer on tuesday for me).

They are really cute little machines: the mill is pretty much a 60cm cube, and the lathe is about 60cm*20cm*20cm.

If I remember correctly the mill at least has a the big "ye-olde-printer" style parallel port which I hope connects to the drivers directly.

I tried the EMC website, ofcourse, but couldn't find any information on this topic. it seems to me it might be some industry standard and so it is assumed to be obvious to anyone involved.

If i'm lucky then this mill is supported right off the bat and I won't have to do any modifications.

i'd be happy to hear form anyone who could shed some more light on this.
Perhaps it makes more sense to post this on the EMC forums.... I guess i'll do that when I have the model and get two birds with one stone...

Re: Connecting EMC to an existing mill
October 19, 2008 08:19PM
Leav, et al,

I just googled:
EMC stepper
and found a bunch of useful links, including this thread:


Looks like a good old parallel port is still supported and common, but that's not the only way to go. Check the current rating on the steppers on your mini mill and lathe -- that'll let you determine whether the rrrf.org stepper drivers can drive them fully -- or whether you'll need higher power stepper drivers. I also see that opto-isolators are recommended. That sounds prudent to me to protect the PC from damage.


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