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### Author Topic: continuous rotation in A B and C at the same time  (Read 440 times)

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#### DonnyM

• 19
##### continuous rotation in A B and C at the same time
« on: December 30, 2018, 10:33:58 PM »
I need to be able to rotate A B and C axis's continuously at various speeds. I can Jog each axis around and around as much as I want but can't to get it to go more than 360 using G code.
Any suggestions on how to set up the Gcode to do this?

thanks

#### joeaverage

• 6,248
##### Re: continuous rotation in A B and C at the same time
« Reply #1 on: December 30, 2018, 11:32:15 PM »
Hi,

Quote
I can Jog each axis around and around as much as I want but can't to get it to go more than 360 using G code.

Why not? How are you generating your Gcode? I suspect you must be using a wizard or a CAM program that rolls over.
You don't have to do that....you can program a move like:

G0 A3600

and the A axis would rotate 36000 or 10 revolutions.

You are correct if you wanted a rotary axis to rotate continuously then eventually when you get to the numerical limit of Mach4
then the DRO would overflow and fault. You would need to check with smurph but I think a number like 4.3 billion degrees,
or 12 million revolutions before that happens.

If you adopted that idea then you could cause coordinated rotation between all three rotary axes and coordinated with all three linear axes as well.
The rotational limit due to overflow would only present a problem with continuous rotation.

If you don't require coordinated motion then you can use up to six out-of-band axes that are supported by Mach4. An out-of-band
axis can be made to index, ie stop at a precise angle but cannot maintain lock step with another axis. All out of band axes can be jogged
in the usual manner (step and cont) which would allow you to have three continuously rotating (no DRO overflow) axes at different speeds.

Craig
My wife left with my best friend...
and I miss him!

#### DonnyM

• 19
##### Re: continuous rotation in A B and C at the same time
« Reply #2 on: December 31, 2018, 09:52:23 AM »
Craig,
Thanks for the info. I was typing in G0 A3600 and it would go to 360. Once I put it in G53 it would go to 3600. The work DRO's do not roll keep counting. But the Machine ones do. For this application that might be fine.
Another issue I am having is the Feed rate display is not showing the RPM value. I have a DRO for each A,B and C to show the current RPM. When the axis is doing say 10 rpm it shows a value of 1800. Whats up with that? The steps per are correct. If I tell it to go 180 deg it goes 180 degrees.

thanks,

#### joeaverage

• 6,248
##### Re: continuous rotation in A B and C at the same time
« Reply #3 on: December 31, 2018, 02:23:04 PM »
Hi,
what setting have you made in Configure/Control/General?

The A,B and C axis DROs display the current angular position of each axis respectively. There is no DRO in Mach4 that displays rpm,
that is angular velocity, not angular position.

You could get Mach to display such a DRO but you would have to code it.

Craig
« Last Edit: December 31, 2018, 02:28:14 PM by joeaverage »
My wife left with my best friend...
and I miss him!

#### DonnyM

• 19
##### Re: continuous rotation in A B and C at the same time
« Reply #4 on: December 31, 2018, 02:40:01 PM »
I had axis roll over checked is why the dro was resetting and not leeting me go past 360. I no longer need to be in G53 to exceed 360

There is a DRO code that is "Current A Velocity" I would think that ould give me RPM but it does not. Any pointers on where to look to figure out how to code a DRO to show the RPM?
Other settings in the general tab I have are Feed Mode Per Min. Distance mode Absolute, Motion CV, Units Metric

thanks,

#### DonnyM

• 19
##### Re: continuous rotation in A B and C at the same time
« Reply #5 on: December 31, 2018, 04:15:44 PM »
I can live with Deg per minute. I just changed the display to state this and not RPM.

While looking under keyboard controls I did not see a way to set hotkeys for the A B and C axis. Is there a option somewhere for that?

thanks,

#### DonnyM

• 19
##### Re: continuous rotation in A B and C at the same time
« Reply #6 on: December 31, 2018, 04:23:30 PM »
Found a way of setting the X Y and Z keyboard controls to the A B and C. I assume that is the best option. IT works just fine since I have no X Y or Z on this contraption.

#### Cbyrdtopper

• 707
##### Re: continuous rotation in A B and C at the same time
« Reply #7 on: January 01, 2019, 11:50:47 AM »
You can try and put some code in the PLC Script that will continuously update a DRO with your RPM Result.
If you can figure out the formula to get the Velocity into RPM then you can put that result in a DRO.  It will update on every PLC Scan.