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Anyone controlling a geneva style tool changer?
« on: May 28, 2012, 05:15:48 PM »
Hey everyone,

I am at the end of my ATC design and have been trying to decide what to do for driving the tool carosel.  I would prefer to use a geneva mechanism for spinning it for more accurate indexing of the tools but have not yet done any looking into how I would control it with Mach.  several things come to mind that may or may not be an issue.  how to have mach understand which tool position it needs to go to when called in a tool change command.  hmm.. that was a bit vague, let me clarify,  if i were using a belt drive setup, i would do it by degrees, my tool changer is a 12 tool unit so i would have tool 1 be 0 degrees and each proceeding tool would be +30 degrees.  so:

T1 - 0
T2 - 30
T3 - 60
T4 - 90... and so on until you are back around at 0

with the geneva wheel, would you do it the same way and just account for each rotation of the stepper to be a block of 30 degrees?  any help or direction on this would be greatly appreciated!

Thanks!

Chris
Re: Anyone controlling a geneva style tool changer?
« Reply #1 on: May 28, 2012, 06:02:45 PM »
use a sensor on the mechanism and count two pulses from the geneva mech for one position change

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Re: Anyone controlling a geneva style tool changer?
« Reply #2 on: May 28, 2012, 06:03:07 PM »
Yes that would be the easiest way if you were planning on using the 360 degree rollover and short rotation on G0 options in Mach.
You want to move one rotation of the stepper but make Mach think it has only moved 30 degrees  you would just work out the steps needed to rotate the motor 1 rev and divide by 30 and that would be your steps per unit. So you command a move of 30 degrees it would rotate 360 on the motor.
Hood
Re: Anyone controlling a geneva style tool changer?
« Reply #3 on: May 28, 2012, 06:11:27 PM »
Yes that would be the easiest way if you were planning on using the 360 degree rollover and short rotation on G0 options in Mach.
You want to move one rotation of the stepper but make Mach think it has only moved 30 degrees  you would just work out the steps needed to rotate the motor 1 rev and divide by 30 and that would be your steps per unit. So you command a move of 30 degrees it would rotate 360 on the motor.
Hood

Hood,

That makes the most sense to me right now.  there wouldn't be any feed back to mach this way but seems to be the quickest way of getting it moving in the correct increments.

is there a place on here to review and learn how to write a macro or code for a tool change where i could learn how to get the parameters for a tool change right? 



use a sensor on the mechanism and count two pulses from the geneva mech for one position change

Not sure i follow exactly, be mindful that i have not yet even looked into mach tool change operations yet, just starting to get some information so i am not totally lost once i am done machining all the parts for the tool changer.

Thanks guys!

Re: Anyone controlling a geneva style tool changer?
« Reply #4 on: May 28, 2012, 06:14:28 PM »
if the geneva is driven from a motor/gearbox setup.

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Re: Anyone controlling a geneva style tool changer?
« Reply #5 on: May 28, 2012, 06:15:31 PM »
I am not the greatest at VB, in fact I am probably one of the worst ;D but do a search for tool change for dummies and you may get some hints there. I think that was for a lathe changer but it used a stepper to drive it so would be similar.

Hood

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Re: Anyone controlling a geneva style tool changer?
« Reply #6 on: May 28, 2012, 06:20:44 PM »
Heres one post with some info, not read through it but I think it should help
http://www.machsupport.com/forum/index.php/topic,19325.0.html

Hood

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Re: Anyone controlling a geneva style tool changer?
« Reply #7 on: May 28, 2012, 06:21:49 PM »
Heres the other one I was thinking about
http://www.machsupport.com/forum/index.php/topic,17567.0.html

Hood
Re: Anyone controlling a geneva style tool changer?
« Reply #8 on: May 28, 2012, 06:54:15 PM »
Awesome Hood, Thanks so much!