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Author Topic: what controls the A axis speed?  (Read 996 times)

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what controls the A axis speed?
« on: October 03, 2016, 10:01:23 AM »
I am doing engraving with code that passed through CNCWRAPPER. The letters come out perfect but the A axis turns very slowly. If I raise the IPM in the command line, any movement that does not involve the A axis goes too fast. I suspect that the slow speed is purely because A is slow so X must slow down too in order to correctly match the programmed path.

How do I increase the speed of the A axis? I tried changing the velocity, restarting the program, and testing the change. No perceived change from 50 to 2000 IPM.

My A axis is a modified rotary table with a 90:1 gear ratio.

If I do G0A90, for example, it runs very fast. But G1F1A90 is very slow.

Guidance most welcome!

Rick
Re: what controls the A axis speed?
« Reply #1 on: October 03, 2016, 02:22:48 PM »
The A axis requires much different parameters to match with the X,Y and Z axis.
There are several settings to be checked as well;
General Config: check A axis is angular; check boxes in Rotational.

Tool Path Config: X - Axis of Rotation; check box Use radius for feedrate; check box A Rotation enabled.

The velocity settings for X,Y,Z are usually all the same, but the Velocity for A is much higher, as well as acceleration.

In my Analog Servo DSPMC milling machine, Steps per for X,Y,Z = 4096; Velocity = 180; Accel = 6
Steps per for A = 1536; Velocity = 1560; Accel = 270
In this setup, the Rotary table is 90:1, and I use this machine for commercial machine jobs, including many  jobs needing
the rotary axis.
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In my stepping motor router: Steps per X,Y,Z = 10160; Velocity = 70; Accel = 30
Steps per for A axis = 2000; Velocity = 120; Accel = 40

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These settings were arrived at by testing, and long term use.  The A axis speed with G0 or G1 is fully in sync with
the linear axis.
As you can see, the Velocity for the A axis is many times higher than the linear axis in both types of machine control.

Just experiment with the A axis settings, and keep raising values. At some point, the A axis motor will stall  so just back off the setting.  You can also write some simple combination moves using X,Y, and A using feedrate for a simple test.

               
Re: what controls the A axis speed?
« Reply #2 on: October 03, 2016, 07:54:01 PM »
Wow! You nailed it. All works perfectly :-)

Thanks for the essential help.

Rick