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Postby Schifty1 » Fri Apr 20, 2018 11:37 pm

Hi Support,
I am a neophyte in CNC, and built my own machine. I am using a UC400ETH, with 542H stepper drivers. Using the MDI interface I can enter G-Code and have the 3 axis move. I was following the axis calibrate process, and I can make the (ex.) X-Axis move 200 units. I measure this as 3.94 inches. Do I enter 3.94 into the "distance measured" box?? It does not accept ", inch, etc. what are the UNITS?? It calculates 10152.28+ is this correct??
Since each of the axis are set up the same, (identical lead screws, steppers, microsteps on the drivers, will this be the same value for each axis??
Thanks in advance for your assistance.
Regards Jeff
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Joined: Thu Mar 01, 2018 7:58 pm

Re: Calibration

Postby cncdrive » Sat Apr 21, 2018 12:02 am

The unit is what you setup the steps per parameter for.
If the setup steps per value of the axis makes the axis to travel one inch when you command one unit to be moved then the units are inches, if the steps per value you setup makes the axis to travel one mm then the units are millimeters. But it could be any other length units the same way.

In the axis calibration you telling the software how far you want the axis to move and then the axis moves and then you measure the real distance moved and type that into the box.
The software knows what your steps per value was and it knows how much you commanded to move and it knows when you telling it how much the axis traveled in real and so it will back-calculate and set the steps per values based on these 3 variables, so with that newly calculated steps per value the next movement distance should be correct.

And yes, if all axis are the same then the steps per values should be the same for all axis. Ofcourse there could be minor differences, e.g. if the ballscrews have some different pitch errors.

I can't tell you if the 10152.28 is correct or not, because I have no information on your stepper drive resolution and your gearing and your ballscrew pitch or rack pitch. I don't know anything about your axis driving mechanism, so I can't calculate if that number is correct. But you can verify if it is correct with doing verification movements after the calibration, commanding the axis to move a known distance and make a measurement on the moved length to see if it was correct or not.
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