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Author Topic: MaxNC and mach3  (Read 5295 times)

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MaxNC and mach3
« on: March 14, 2008, 10:34:04 PM »
This isn't really a question - just thinking out loud.

Just picked up an old MaxNC OL controller, a win95 PC  :(  with MaxNC loaded and 3 steppers. This is going to be my budget lathe controller but the last thing I need is another PC so I'm hoping to get it working with Mach3 and share the PC I have on my router.

Plugged everything into the win95 PC and all three axii jog (albeit slowly) just to make sure it's all working.

Plugged it into an XP PC to test with mach3, set MaxNC-10 wave mode and the motors twitch but don't spin. I'm guessing I need to check the motor phases are wired exactly right. MaxNC seems to let you wire up the motors anyway you want, then has a sequence checker program so you can cycle through all the possible combinations until the motors turn smoothly.

I also grabbed the MAXNC pinout diagram from the FTP site so I'll put a scope on the LPT port to triple check the 12 output phases are in the right places.

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Jon

Re: MaxNC and mach3
« Reply #1 on: March 15, 2008, 02:23:43 AM »
So... rearranged the wiring and all 3 motors are spinning nicely.

Now I do have a hypothetical/theoretical question. I realise MaxNC support isn't a priority and we're lucky to have it work at all :) but since all the MaxNC driver circuit does is turn the 4 outputs  for each stepper into power for the 4 phases then wouldn't it be possible to run exactly the same hardware in full-step (for more torque), wave and half step modes from Mach since all that requires is modifying the bit patterns that are output? I'm guessing full-step would run hotter (although you could switch to wave when the motor wasn't turning)

--

Jon

Offline jimpinder

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Re: MaxNC and mach3
« Reply #2 on: March 16, 2008, 06:25:02 AM »
The answer is no.

Drivers do more than amplify the signal from the computer. It is them that arrange the pulse patterns to the different segments of the motors.

All Mach 3 does is provide two pulses, one for each step, and one (usually continuous) for direction - per axis. Your drives sort this out to a four wire signal to the motor.

The MaxNC says it can be used with other software (i.e. Mach3), and so it follows the same pattern - two outputs per axis.  On my drives there is a switch to change between full, 1/2, 1/4 and 1/8 step for the motors - not in the Mach3 software.

I,m afraid if you want more power, you will have to get bigger motors.
Not me driving the engine - I'm better looking.
Re: MaxNC and mach3
« Reply #3 on: March 16, 2008, 07:37:04 AM »
Actually MaxNC OL uses 12 outputs from the parallel port - 4 for each axis which are amplified directly into the stepper phases. The maxNC driver (if you can call it that) has 3 7400 chips, 12 power transistors, 12 resistors and the power supply - it's definitely not doing any sequencing itself :)

Mach has a special "maxNC wave mode" which cycles the correct bit patterns on the output to turn the motors so my question about theoretically supporting full step and half step is valid.


Offline jimpinder

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Re: MaxNC and mach3
« Reply #4 on: March 16, 2008, 12:48:23 PM »
Sorry - my mistake - I googled Max NC and they appear to have a driver card that runs off the normal step and direction wires. Yes - now I look again at Ports and Pins I see the Max NC selection.

So in answer to your question - must be a yes, but I will have to hand you over to those who do the programing to say if and when.

The only drawback I can see is you have used all your outputs - so controling spindle, and coolant even, would require some sort of second port - and that would ruin the idea of a budget system. I personally would buy a set of "normal" cards for drivers - there is just enough input/output on LPT1 to control most aspects certainly for lathe work, and you could certainly set up one PC to control a number of "outlets" then
Not me driving the engine - I'm better looking.