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Offline Chip

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Re: rotary axis setup
« Reply #10 on: November 22, 2006, 04:19:04 PM »
Hi, All

The diameter set's the feed rate, a 1 in. dia and 10 in dia. will have different feed rate's so the actual surface cut speed will be the same.

Just an example of my setup, 1 full turn of your table (the number of step's it takes) divided by 360 = 1 degrees step's required.

As far the .2 if it doesn't divided out evenly then, I think Mach keeps track of the number else, you would have cumulative error in 1 full turn.

Your's may be even number's

Thanks, Chip
Re: rotary axis setup
« Reply #11 on: November 23, 2006, 11:52:16 AM »
Hello,

  I just set a 4th axis up on my Taig. I bought a 6 inch rotary from Grizzly, a 207 oz stepper from Circuit Specialists and I am using the original Taig controller.

My settings for A axis:
Steps - 80
Vel. - 50
Accel - 400
Pulse - 13
Dir pulse - 1

1 degree = .125
So I just multiply the degree desired by .125 and it goes there.

eg. 360 x .125 = 45 (360 degrees)
eg.  10 x .125 = 1.25 (10 degrees)
eg 22.5 x .125 = 2.8125 (22 1/2 degrees)

Hope this helps,
Robert

Offline Graham Waterworth

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Re: rotary axis setup
« Reply #12 on: November 23, 2006, 02:03:43 PM »
You are making life hard for yourself,

If your rotary table is 50 to 1 ratio and your motor is 200 steps per rev multiply 50*200 and this is your steps per rev

set velocity and accel to what ever it will index at safely

That way if you want it to move 90 degrees you enter G00 G90 A90.

Graham.
Without engineers the world stops

Offline Chip

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Re: rotary axis setup
« Reply #13 on: November 23, 2006, 03:03:39 PM »
Hi, Graham

I think that work's fine for Linear, but unless there have been changes in the last couple of rev. of Mach3R2.0 to get A axis Rotational

speed up you need the 1 deg value in step's in A unit's Motor Tuning. Full turn step's divided by 360 = value.

May be fine with A axis that have closer step's ratio's (A10,000, X,Y,Z,2000) not for (A144,000, X,Y,Z,2000) Step's, very very slow.

I don't really understand why its not compensated for in the software so actual step's per 1 full rotation of a axis could be used in setup.

Way, way beyond Me.

Thank's, Chip

Offline Graham Waterworth

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Re: rotary axis setup
« Reply #14 on: November 23, 2006, 03:26:41 PM »
I see your point,  25,000 steps per port pin per second is probably the reason.

I built my rotary indexer at 10:1, thats probably why mine is fine.

Graham.
« Last Edit: November 23, 2006, 03:30:14 PM by Graham Waterworth »
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Offline Chaoticone

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Re: rotary axis setup
« Reply #15 on: November 23, 2006, 03:43:53 PM »
Just a question. Does it matter? It is going to take the same amount of step pulses per rev. right? Is it going to matter if you set it up for 1 minute, 1 degree, or one reveloution? A couple of thoughts on things that might help would be to do a belt drive (1-3 or 4) and get away from micro stepping?

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Offline Chip

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Re: rotary axis setup
« Reply #16 on: November 23, 2006, 04:47:33 PM »
Hi, Chaoticone

That's true a non micro stepping A axis would help allot on My R-Table, it would decrease the resolution but balance out the large difference

in A verses X,Y,Z, step's required, would be 6.67 to .66 Step's Per. Minute, more or less.

If I've done the Math properly, Still need's to be per 1 deg. for any speed though.

Just some trade offs.

Thank's Chip

« Last Edit: November 23, 2006, 05:00:27 PM by afn09556 »

Offline Chaoticone

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Re: rotary axis setup
« Reply #17 on: November 23, 2006, 05:15:56 PM »
Yes, but wouldn't it also help the speed? If 25kHz is the problem. I have a rotary table I would like to hang a motor on. ;D It is 90-1
With microstep and 1-1 gearing 200 X 10 X 90 =180,000 steps per. rev. 4.0 seconds per rev. I'm running at 45KHz  ;D
W/O microstep and 1-1 gearing 200 X 90 = 18,000 steps per rev. 0.4sec per rev. with a res. of .02 degrees. I think this is about 1.25 minutes. I'm just asking because I don't know. What kind of res. is acceptable? ???
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Offline Graham Waterworth

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Re: rotary axis setup
« Reply #18 on: November 23, 2006, 05:54:59 PM »
Accuracy is all relative to the diameter you are working at,  if you are working at 1" dia 1.25 minutes of arc is nothing, if you are at 20" dia it may be a problem.

Graham.
Without engineers the world stops

Offline Chip

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Re: rotary axis setup
« Reply #19 on: November 23, 2006, 06:01:32 PM »
Hi, Chaoticone

The 25kHz isn't rely the problem it's the way Mach treat's linear versus Rotational setup.

If I get some time later, I'll post 2 different way's to look at it, then it will be clear

Hi, Graham, This is very true.

Thank's, Chip