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4 th axis rotation
« on: January 05, 2013, 11:37:06 AM »
Hi

       I' ve built my 4th axis rotary indexer not sure what I did wrong when I go into mdi and type in g0 a45 the indexer rotates full circles
not the 45 degrees. Ive specified. I saw somewhere on here to specifiy my a axis as rotational in general config but i cant find that setting any ideas please.


                                                         Thanks
                                                         Gary

Offline Hood

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Re: 4 th axis rotation
« Reply #1 on: January 05, 2013, 12:51:24 PM »
Multiply  the steps per unit by 8 for the A and see if that helps.
Hood
Re: 4 th axis rotation
« Reply #2 on: January 05, 2013, 12:58:05 PM »
Just a question why would you multiply by 8 ?  If I have my stepper driver set to 1/16 wouldnt it be 16 ? Just asking ?


                                                    Thanks
                                                     Gary

Offline Hood

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Re: 4 th axis rotation
« Reply #3 on: January 05, 2013, 01:00:53 PM »
You said it moves 360 degrees when you command a move of 45degrees. That means it is travelling 8 x too far so your steps per unit are 8 x too small.
Hood
Re: 4 th axis rotation
« Reply #4 on: January 05, 2013, 01:33:44 PM »
That changed it some my biggest problem is that I dont have any documentation for the motor I'm not sure if it is 200 steps per revolution or not is there any way to figure this out ? Thanks for your help !

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Re: 4 th axis rotation
« Reply #5 on: January 05, 2013, 01:57:34 PM »
Tell me a little about your setup, is the motor direct coupled to the rotary or is there gearing ? If geared what amount?
Hood
Re: 4 th axis rotation
« Reply #6 on: January 05, 2013, 05:38:09 PM »
I'm using a drive belt with 2 pulleys it is a 40 to 1 ratio .

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Re: 4 th axis rotation
« Reply #7 on: January 05, 2013, 05:45:11 PM »
Ok so in a rotary axis with 200 step per rev stepper and 1/8 stepping it would equal 177.7777777 steps per unit, for a 0.9 degree stepper( 400 per rev) it would be 355.555555
 Meant to say the rotational axis setting is on General Config page.
Hood
Re: 4 th axis rotation
« Reply #8 on: January 05, 2013, 06:14:44 PM »
How should that setting should be set at ?  I tried the numbers you mentioned . If I tell the machine go  a45 I not sure how many revolutions the chuck rotates . I think the motor has some sort of weird steps  per revolution number. I have my stepper driver set at  1/16  steps . Is there any way I can use the calibration tool in Mach 3 to set this up?

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Re: 4 th axis rotation
« Reply #9 on: January 05, 2013, 06:28:21 PM »
If you have 1/16 setting then you would need either 355.5555 or 711.1111111 steps per unit.
Also make sure it is set as a rotational axis on Genral config page.
Hood