Motor Tuning

[PEU]

Im a bit dissoriented, Im reading section 5.5 of mach3 manual and I still need to ask some questions:

I have:

Xylotex motors (269oz/in 1.8deg 200 steps p/turn)
PMDX150 (allegro3977 based board) set to 8 microsteps
So total steps per turn is 1600

8mm per turn NSK ballscrew attached directly to the motor (no belts)


So, in the motor tuning screen I enter: (mach3 is set to mm units)

Steps per mm= 200 (1600/8mm or 200x8/8)
Velocity= 2540 (I put this because is the same as 100ipm)
Accel=600 (guessed this one)

With this setting the motors turns just fine, but if I enter another combinations they run fine too, so here comes my questions:

How do I calculate the best setting?
Which is the most important setting and why?

I've looked for posts explaining this and to date found nil.

Thanks in advance


Pablo

[MrBean]

I found the highest velocity setting that my motors would run at without loosing steps and tuned it down by around 20% just to be safe.

If you're checking your motors by jogging. I found that mach3 defaulted to 50% jog speed. You may want to check that, if that's how you're testing your motors.

Regards Terry.

[KaptainKarst]

Here's what I do to fine tune the motors after the velocity and accel has been dertermined (see other post for that good advice).
I started with the rough calculation for steps per inch. In my case the math worked out to 4000 steps per inch.
So I entered that (4000) into the X axis "steps per unit" box.

I then set up a dial indicator and issued a command for the X axis to travel one inch (after I had manualy taken up the backlash...get to that later).

After the travel stopped I read the dial indicator and it indicated 1.012 inches of real travel.

Here is where the "fine tuning" comes in. take the previous "steps per unit" (4000) and divide it by the 1.012 inches of real travel = 3952.57. This is the NEW value that I enter into the "steps per unit" for the X axis.

I repeated the above process several times until I got it to repeat dead on the money every time. I then duplicated this process to the Y and Z axises.

Now for backlash. rotate the lead screw to remove any backlash. setup your dial indicator and comand your system to move by .25 or so in the same direction. Then command the machine to return to zero. The dial indicator will show you your backlash. Repeat this a couple of times to be sure. Then you can enter that value for the particular axis under the "backlash" under the config dropdown menu. Be sure to also ENABLE BACKLASH under Config/State/Backlash ON option.

Repeat this for all axises and you should now be pretty well setup.....
Jim

[PEU]

in mach3 settings screen there is an axis calibration tool (steps p/unit button) that does what you just described Jim.

I still cant measure backslash because the setup is not finished, but will try the technique for sure!

Thanks


Pablo