Denford Software & Machines

I have a year 2000 Trial VMC. I am converting it to use Mach3 software.
I know the ball screws are 5 MM pitch. But I don't know what the motor pulley ratios are.
My question is how many steps on each axis (X,Y,Z) does it take to move that axis one MM?

Thanks,
Mike Brooks

Its 200 steps per mm looking at our older control software parameters.
The original control was probably running half step mode, so you get 400 steps per rev of the motor.
So 1 rev of motor gives 2mm meaning the pulleys will be 2.5 : 1

This all sounds about right, the more I think about it ...

Don't bother trying to work it out !

Go to the settings page, on the left hand side there is a button for set axis steps. Now measure the position of the table to a handy reference point with your verniers. When you click the button it will ask you which axis to move followed by the amount. Enter a value. wait for the machine to move, enter the actual distance moved, hit ok and your done! Repeat for each axis. Job Done

Cheers

Dave

I guess MAch will tell you the steps per mm and let you change it manually ?

Just thinking that if backlash or measuring is a bit off, you may get an odd number like 198 steps/mm

Yup, it will automatically work out the steps per unit (depends on whether the machine has been built in inches or mm's). You can adjust this manually, but shouldn't really need to.

Backlash is another issue again. When you set the steps per unit, you need to ensure that you have accounted for the backlash, so, before running the setup make a +ve move on the axis you are going to set. Then when asked for distance to move enter a +ve value.

For backlash you need -
move +ve
Set axis to zero and measure position with verniers
Move +ve (e.g to 10) - measure position to confirm the correct amount moved.
Move -ve to 0, measure position. The difference between this and your first measurement is a good approximation for backlash. You may find that when you start machining you have to tweak the values slightly to get it spot on.
If you want to repeat, now go -ve, then +ve to zero etc to ensure you have removed the lash.

Cheers

Dave