How to perform motor turing for a rotary axis?

[ZeroBacklash]

I understand a bit of how to tune a linear axis, i mean either of the x, y or z axis from the motor tuning dialog.
I did this with a dial guage attached to an axis and then with Mach3 told the axis to move 1 mm and then fed back the dial guage measurement into Mach3 and it did the necessary motor tuning calculations. I mean it calculated the steps / mm.

Now I need it to do for the A axis, but have no idea how to connnect a dial guage to a rotary axis. I though it should have been in angles but Mach 3 shows the same mm dialog for rotary axis like the linear axis.
So if I tell mach3 to move A axis by 1mm how do i measure 1mm movement on the A axis with a dial guage?

Thanks in advance.

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[ger21]

Rotary axis are setup in degrees. It's pretty simple. steps per rev (200?) x microstepping x gear reduction /360.

To fine tune it, put a mark on the chuck, and have it make 50 (or so) revolutions, and see if it ens up on the mark. If not, adjust and try again.

[ZeroBacklash]

Rotary axis are setup in degrees. It's pretty simple. steps per rev (200?) x microstepping x gear reduction /360.

To fine tune it, put a mark on the chuck, and have it make 50 (or so) revolutions, and see if it ens up on the mark. If not, adjust and try again.

Ok, So I don't need to use the motor tuning dialog to do that? correct?
The problem being I don't know how much microstepping the driver is step up for.Basically all the machine controls are in a box, and the last time I opened it, it had different PCB's for each driver. I will have to open it up again to check if there are any dip switches for microstepping.
So is there any way I can do it without knowing what is the current microstepping setting in the driver?

[ger21]

Are you talking about the calibration when you say motor tuning? If so, that would be a bit trickier to do, as I don't think it was designed for calibrating a rotary axis.

[ZeroBacklash]

Are you talking about the calibration when you say motor tuning? If so, that would be a bit trickier to do, as I don't think it was designed for calibrating a rotary axis.

Yeah I guess I probably used the wrong word. When I go into the Settings tab there is a button in there called "Set Steps per Unit" under Axis Calibration
Where it shows all the axis.
So how do I tell Mach3 the steps / mm or rather steps / deg for a rotary axis?
Do I have to manually do this like what you said earlier by putting a mark on the chuck and then rotating it 50 turns.

[ger21]

You manually enter the steps/degree in the "Motor Tuning" screen.

[ZeroBacklash]

You manually enter the steps/degree in the "Motor Tuning" screen.

So is there a way where I can tell Mach3 to send to the stepper driver X step commands,
So that way I could back deduce the microstepping setting in the driver.
The driver is a TSS-TB6560-V1.0 but I have no idea what the dip switch settings are.

[CitizenOfDreams]

So is there a way where I can tell Mach3 to send to the stepper driver X step commands,
So that way I could back deduce the microstepping setting in the driver.

Just set your "steps per unit" value based on microstepping of 8 (somewhat a middle ground). Then tell the machine to move 1 inch and see how far it moves.

If the machine moves 1 inch, then your microstepping is indeed 8. If it moves 2 inches, then your microstepping is 4. If it moves 1/2", then your microstepping is 16, and so on.

For a rotary axis, tell the machine to move 1 turn (360 degrees) instead of 1 inch.

[ZeroBacklash]

Attaching pics of the stepper driver, if someone can help me figure out the DIP switch settings, it would be awesome.
TIA

[ZeroBacklash]

Just set your "steps per unit" value based on microstepping of 8 (somewhat a middle ground). Then tell the machine to move 1 inch and see how far it moves.

If the machine moves 1 inch, then your microstepping is indeed 8. If it moves 2 inches, then your microstepping is 4. If it moves 1/2", then your microstepping is 16, and so on.

For a rotary axis, tell the machine to move 1 turn (360 degrees) instead of 1 inch.

Ok that's great for a start, so how do i tell the A axis to move 1 turn? do i have to write some g code for it, or is there a way in Mach3 gui to tell the A axis to rotate 1 turn?
Another part of the problem being that the rotary axis chuck is not directly driven by the stepper motor, it is belt driven by a timing belt and 2 pulleys. A small pulley attached to the motor and a larger diameter one attached to the chuck.

[CitizenOfDreams]

Ok that's great for a start, so how do i tell the A axis to move 1 turn? do i have to write some g code for it, or is there a way in Mach3 gui to tell the A axis to rotate 1 turn?

You can jog the axis manually until the DRO advances 360 degrees. Or you can issue a G-code command in the MDI tab: G91 G0 A360.

[CitizenOfDreams]

Another part of the problem being that the rotary axis chuck is not directly driven by the stepper motor, it is belt driven by a timing belt and 2 pulleys. A small pulley attached to the motor and a larger diameter one attached to the chuck.

That is not a problem. How many teeth does each pulley have?

[ZeroBacklash]

That is not a problem. How many teeth does each pulley have?

The belt is wrapped over it tightly so I'm finding it difficult to measure. Unless I'm missing a simple measurement trick.

[CitizenOfDreams]

Is there a gap where you can see at least one tooth? Rotate the axis and see how many teeth pass through that gap in one full turn of the pulley.

[ZeroBacklash]

Is there a gap where you can see at least one tooth? Rotate the axis and see how many teeth pass through that gap in one full turn of the pulley.

The small pulley is 16T and bigger pulley is 75T

[CitizenOfDreams]

The small pulley is 16T and bigger pulley is 75T

In that case, your "steps per unit" value is:
200*8/360*75/16=20.8333 (assuming 8x microstepping).

[ZeroBacklash]

In that case, your "steps per unit" value is:
200*8/360*75/16=20.8333 (assuming 8x microstepping).

This is simply amazing, many thanks, I worked that equation over try to reach your conclusion, and eventually understood how it all works. Many thanks for your fabulous answers!

[ZeroBacklash]

You can jog the axis manually until the DRO advances 360 degrees. Or you can issue a G-code command in the MDI tab: G91 G0 A360.

Er! So based on what you said that if the microstepping is set to 8x.
The motor pulley will run at 8 x 200 = 1600 steps / rev.
The chuck pulley will run at 72/16 * motor pulley step = 4.5 * 1600 = 7200 steps / rev.
So is there a way in Mach to accurately step 7200 times for the A axis, I guess there is no provision to jog an axis a fixed number of steps?
Is issuing a gcode command the way you mention the only way?

[CitizenOfDreams]

Er! So based on what you said that if the microstepping is set to 8x.
The motor pulley will run at 8 x 200 = 1600 steps / rev.
The chuck pulley will run at 72/16 * motor pulley step = 4.5 * 1600 = 7200 steps / rev.
So is there a way in Mach to accurately step 7200 times for the A axis, I guess there is no provision to jog an axis a fixed number of steps?
Is issuing a gcode command the way you mention the only way?

You said "75 teeth" originally. If the pulley has 72 teeth, then the "steps per unit" would be exactly 20. I guess the pulley ratio was intentionally designed to give you a whole number of steps per degree.

[ZeroBacklash]

You said "75 teeth" originally. If the pulley has 72 teeth, then the "steps per unit" would be exactly 20.

Yes indeed that was a typo. I mean the 75T is correct.
so the ratio is 75/16 = 4.6875
And then the steps per rev for the chuck pulley would be 7500.
So how do I accurately step the A axis by 7500 steps?