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rotary axis turning really really slow
« on: January 13, 2008, 08:20:12 PM »
I have built and installed a 4th axis on my machine.  I have seen several posts regarding this but have not discovered a solution to my problem.
My "A" axis is set to 22.222 steps per, 10002 as the velocity and 1700 as the acceleration.

The problem is that when you are doing a move that uses one of the linear axis, say the "Y", and the "A", the feed rate may be 35 ipm or similar.  It takes forever for the rotary axis to move to the desired position based on that feedrate.  How do you deal with this big difference?

Can someone help me out?

Offline docltf

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Re: rotary axis turning really really slow
« Reply #1 on: January 13, 2008, 08:51:29 PM »
your velocity spread is pretty wide 1700 vs 35
try this first.
motor tunning set your Y axis maximum velocity to 35 ipm that way it will have a max out.
then change your feed rate in you g-code from f35 to bigger numbers like f550 or f1500.
it would be better to start a little low and work  your way .mach has to have a chance to turn your A quicker
without overcooking your Y axis.

bill

Offline Bodini

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Re: rotary axis turning really really slow
« Reply #2 on: January 14, 2008, 02:55:12 PM »
Assuming your 4th axis is set up correctly, the best way is to do this:



go to Mach-->[pull down menu] Config-->  Tool Path -->  find the "Rotations" box

select "A- rotations enabled"

and

"use diameter for feedrate"

Now go to the "Settings" Screen in mach (the tabs at the top of the mach interface)  it says "Settings Alt6"

Find the "Rotation Diameters" area

enter the diameter or your finished piece in there.



Now Mach will automatically set the speed, like F50, to cut 50 units per minute along the circumference of the work.

It's a great feature that I use everyday.  You can also adjust the speed by changing the diameter without having to change g-code.

-Nick

Re: rotary axis turning really really slow
« Reply #3 on: January 15, 2008, 08:30:06 AM »
Nick,

I understand what you are saying about setting the diameter.  But if the feed rate is set to 50 units per minute or similar that is still really slow for the rotary axis.  What is the steps per uit on your setup?

Thanks!

Offline Bodini

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Re: rotary axis turning really really slow
« Reply #4 on: January 15, 2008, 10:35:38 AM »
Steps: 19.047
Vel: 40,002
Accl: 4100
Re: rotary axis turning really really slow
« Reply #5 on: January 15, 2008, 10:50:54 AM »
I will try that when I get a chance.  I am a little confused about how that works but am willing to give it a try.

Thanks!