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Author Topic: Machine loosing position when estop  (Read 3388 times)

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Machine loosing position when estop
« on: September 12, 2008, 07:10:32 PM »
Since i installed the dev version of Mach and the SS I notice that anytime I hit the Estop button my machine loses its position on the axis thats moving. It only effects the axis thats moving when the estop is hit.  Is there a setting I have missed  somewhere/
Re: Machine loosing position when estop
« Reply #1 on: September 12, 2008, 07:12:25 PM »
That sounds pretty typical. After any e-stop, you should re-home/reference the machine.
RC
Re: Machine loosing position when estop
« Reply #2 on: September 12, 2008, 07:13:46 PM »
I should say...."ESPECIALLY" if there was an axis in motion at the time.
As the axis stops IMMEDIATELY with no deceleration, it will most likely lose track for sure.
RC
« Last Edit: September 12, 2008, 07:16:11 PM by Overloaded »
Re: Machine loosing position when estop
« Reply #3 on: September 12, 2008, 07:26:49 PM »
Since i installed the dev version of Mach and the SS I notice that anytime I hit the Estop button my machine loses its position on the axis thats moving. It only effects the axis thats moving when the estop is hit. Is there a setting I have missed somewhere/

If you want to stop gracefully, and not lose position, use FeedHold, not E-Stop or Stop.  Using E-Stop when the machine is moving is pretty much guaranteed to lose position, as Mach simply stops sending step pulses, and has no idea how far the machine will coast before actually stopping.

Regards,
Ray L.
Regards,
Ray L.
Re: Machine loosing position when estop
« Reply #4 on: September 12, 2008, 07:39:53 PM »
Odd part is I have hit estop thousands of times over the past four years on this very machine  and never lost zero or had the machine coast more than .0005"  but now (post ss instal) if I am moving in the x axis at speeds as slow as .5 IPM and hit the estop it will throw the DRO off .276" everytime , regardless of speed", I am running huge DC servos and their is no way the table is moving anymore than .001 after the estop is hit , and surely not over 1/4" . Its not a high speed or inertia related problem its something software related , If I estop while the z axis is moving , even as slow as 1 IPM it will be off .600" everytime . I am familiar with coasting/inertia after hitting the estop and thats not the problem in this case.
« Last Edit: September 12, 2008, 07:41:37 PM by panaceabeachbum »
Re: Machine loosing position when estop
« Reply #5 on: September 12, 2008, 07:42:40 PM »
Could be related to the excruciating speed of the SS pulsing engine.
RC

Offline jimpinder

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Re: Machine loosing position when estop
« Reply #6 on: September 13, 2008, 04:46:59 AM »
I'm afraid Mach is NOT guaranteed NOT to loose position when you hit E Stop. That's the whole point - stop the axis moving as quick as they can.

Are you saying the axis stops moving, but the DRO's keep moving, or do the DRO's stop and then the axis slides gracefully to a halt
Not me driving the engine - I'm better looking.

Offline RICH

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Re: Machine loosing position when estop
« Reply #7 on: September 13, 2008, 07:34:01 AM »
May be off base here, but go to the Warp forum and check out the revision comments associated with SS plug-ins. I think there was a bug that Greg fixed for the SS relating to the E-stop.
RICH
 
Re: Machine loosing position when estop
« Reply #8 on: September 13, 2008, 09:21:04 AM »
Thanks Rich , its def a  software bug , I will check it out

Jimpinder whats happening is when I hit the estop button the machine and DRO both stop moving instantly just as they always have and then the DRO jumps by .276 on the x axis and .600 on the z .   The table doesnt coast tp this position and the DRO isnt ramping down. 

 Just as its always done the table and DRO stop instantly , but now the dro on those two axis changes by exactly the value above after estop  .