EMC linux + CNC mill + CNC Lathe

[Leav]

Hello Netizens of ChiefDelphi,

Our team found a CNC mill and a CNC lathe in the back of the tech class store room.

Degem TP MI CNC mill
EMCO Unimat PC (not the "basic" model, the one under it)

Our problem, in both cases, is that we can not find the computer or the software supposed to run these machines,so I was thinking perhpas EMC might work, but I have never used it and have no idea what is needed to set it up.(the website is... not very coherent to me - to say the least).

So I have some questions which I am sure people here will be able to answer, since some of them are general questions about CNC:

1. How do stepper control boards(stepper drivers?) work? what is the input signal? (single pulse for each step on a control line?)
2. I know stepper motors are controlled by stepper drivers, but how are these drivers connected to the PC, and is there some sort of standard?
3. I gather that the PC connects to the boards through the serial port, is this correct?
4. How can I tell what the pinout should be on the serial port?

As you can see I don't think i'll have much of a problem setting up EMC, and I have a basic understanding of how the mill works, but I aam completely lost on how to bridge the two worlds, and non of the above have any information to help me out here.
Specifically it seems to me that I lack some basic knowledge about CNC setups that the EMC website assumes that I have.

Thanks very much for your help!
-Leav

[Leav]

Small update: just got off the phone and it seems that the mill has an LPT1 style parallel port.

How does this bode for connecting to a pc running EMC?

They tried selling me a 350 euro kit for conversion from parallel to serial, and 150 euro software for it.

I think ill go with the 0 euro upgrade to EMC, if I can

-Leav

[chris31]

Originally Posted by Leav

Small update: just got off the phone and it seems that the mill has an LPT1 style parallel port.

How does this bode for connecting to a pc running EMC?

They tried selling me a 350 euro kit for conversion from parallel to serial, and 150 euro software for it.

I think ill go with the 0 euro upgrade to EMC, if I can

-Leav

A laptop might not have a parralle port but a desktop most likely will. I have never played with EMC but its a Linux distribution. I dont know how straightforward the install and use of it is, but if you dont have any background in using Linux it might take some time and be a pain to set up.

[Andy Brockway]

You might try http://www.machsupport.com/
or http://www.dakeng.com/turbocnc.html

I have run both thru a xylotex control system. Both have the ability for you to tune the drivers. Mach has more features and I use it to develop the g-code but the computer I am running my CNC router is old, so I am running TurboCNC there.

There are many more free software solutions. These two are pretty common. Check out http://www.cnczone.com/

[Leav]

Thanks guys!

Regarding Linux - I have no problem running linux, I am very fmilier with it and have been running it as my main OS for several years now.

Regarding the software - I am not particulerlay concerned with the software itself, but more with the interface between the software and the hardware.

Is this LPT1 connection a standard thing, or will I have to modify the signal? will it just involve finding the right pinout?
if so, how do i find that pinout?

How are stepper boards controlled? is it a standard way, or will each board have it's own special way of communicating with the computer?

Thanks for helping me out!
-Leav

[Leav]

Andy, I went through the TurboCNC (reminds me of Turbo Pascal ) and found this website:

http://www.seanet.com/~dmauch/

it uses frames so I can't direct link, but in the menu click on "secrets of CCNC", and scroll down a bit: there is a whole section explaining how the parallel port control works and a whole lot more useful information.

Thanks again Andy!

-Leav

[Andy Brockway]

Most of the software packages will have the pinouts. I have seen that most control boards use a standard for x, y and z axis. Some, like Mach, let you configure all the pins to match non standard pinouts.

Good luck with resurrecting your machines. They look fairly new so should be adaptable. The control system for my router had a 25 pin serial port and the software was not available. I was able to wire a new control system to the existing steppers.

[tdlrali]

LPT1 is just another name for the parallel port (something like local print terminal). Any parallel port will work, as long as the software supports the same protocol as the mill.

[VEI Dude]

Leav,

Does your mill & lathe have drivers already? Or do you need those?

Here's my summary of how all the pieces work, in reverse order. I'm basing my values on general hobby/training-sized machines, which it seems is what you have. Note that this is a bare scratch of the surface of info on these devices...
(1) The stepper motors move in very small, but well defined increments with each "pulse" it receives from the driver -- common is 1.8 degrees per step (200 pulses per rev). Some motors are bi-polar and others are uni-polar, and some of these motors can be wired as the other type.
(2) Once you determine what type of motors you have, you need matching drivers. The drivers put out a (relatively) high voltage to power the stepper motors. The drivers usually take a 2-wire signal -- one is the direction (high or low digital level), and the other is a step (one pulse for each step). If you don't have drivers already, look into Geckos (a bit pricey, but very capable), IMS, Xylotex, and others.
(3) The drivers require a high-voltage, high-current motor power supply (usually 30V to 70V and a few to 10A or 20A, depending on the driver and motor), and a low-voltage, low-current control power supply (usually like 12V or 5V).
(4) The drivers get the step and direction signals (one pair of signals for each axis of your machine) from a parallel port (usually). You can get a breakout board to simplify extracting the signals from the parallel port. Some of these cost as low as $10. Note that some laptops have very low signal levels from the parallel port, so get a buffered breakout board for a bit more $$$. Check out places like cnc4pc.com .
(5) If your machines have control of the spindle, or coolant, etc, you will can also get the control signals for those from the breakout board.
(6) For software, as much as I am a Linux guy first, I must admit that setting up Mach3 with Win2000 was much easier than EMC. The free version is limited in number of lines, but it's still a LOT of lines. You might try that to get started much quicker.
(7) You can write g-code manually for now, then later get a decent cad-cam program to generate the code for you.


Some other notes...
- Common convention is ... On the mill, X is left to right, Y is forward and back, and Z is up/down. On the lathe, X is forward-back, and Z is left to right. Yes, it's odd, but Z is always considered to be along the axis of spindle rotation.
- You'll come across "microstepping". This is the ability of the driver to step the motor only partially for each step pulse. You get smoother operation and better resolution, but the PC needs to send out many more pulses per second. 8 microsteps is usually good enough. 4 is decent, but 16 or more is usually not noticed.
- Steppers may show a few volts listed on the label (like 2 or 3 volts), but you would power it with a supply about 20 to 25 times that (yes, going up to 70 volts or so). Reason is that the high voltage gets current to the motor windings much faster, and the current-limiters in the driver will switch the voltage off accordingly at the right time to not overdrive the motors.
- A CNC machine does not absolve you of learning to machine (endmill types, speeds, feeds, depths-of cut, workholding, etc.).
- Get on cnczone.com and machsupport.com . Good info there.

Cheers,
-Neil.