mits m3 control wont find home in y axis

[trademark]

Hi all;

I have a dyna myte dm4800 with a mits m3 control. It has been a great machine up untill monday. (yeah i still like it a lot)

Machine was running fine on sunday .came in monday morning and turned on machine and it will not find home position in y axis. x and z home out ok.



the standard home procedure is to set the selector switch to home. then select the axis to home and press the home button. you then do this for all 3 axis.

when you press the home button the axis moves at a fairly fast rate till it hits the home limit switch. It the slows way down till it finds the zero mark on the encoder (i think its the zero mark)

in my case the y axis never makes the fast move. it moves at the slow rate till it hits the software limit.

if i try to home y till it hits the software limit and then home x and z. I can move all 3 axis in rapid and with the handwheel. (the handwheel works all the time even before homing) the position conters seem ok on all axis.
The program will not run . error is no home position

things i have tried:

1. tested home limit swith seems ok
2. tested overtravel limit ok
3. checked parameters most match my documentation. the ones that do not dont seem to be connected.

4. I tried moving my soft limits to allow the encoder more travel did not help
5. swapped x and y encoders no help
6. reseated io board in control and io plugs no help

any suggestion would be helpful
Mike

[trademark]

Well i checked my y home switch again today and it seems it is intermiently bad.

I was able to get it to home by playing with the switch.

Can someone explain what happens during the home cycle on this machine/control ?
does anyone have any good sorces for a yamatake ldvs-5304s limit switch?
I will be checking ebay soon

thanks
Mike

[botha.y]

Just replace your switch by an identical one, that should pretty much solve your problem. Doubtfully but possibly could be the wire or the connection to the I/O unit. 99.99% sure it is your switch. Cheers.

Botha

[trademark]

Botha:

I will be in your neck of the woods in a few days..
Have a trip thru Maine and lower Canada planned ....leaving tomarrow.

The new switch is on the way..

Thanks

Mike

[onthebumper]

I agree the switch should fix your problem.

During the zero operation the following happens.
-The axis heads to zero at a faster rate. until it hits the switch.
-Once the switch is made the axis shifts to a slower speed.
-The dog moves off of the switch but the axis keeps moving.
-Once off of the swith the control looks for the Z pulse from the encoder and finds home based off of the Z pulse.

In your case since the axis never speeds up, it looks like your switch was stuck closed in which case the cnc will never look for the Z pulse because the switch never opens up.

[botha.y]

And that's an example of a standard use for home, but there are other possible configurations for homing depending on how params and machine is set up. And limit switch has thousands of reasons that it does not work. Sometimes it just doesn't click anymore, sometimes it clicks but have to be fully pressed and dog is not tall enough to completely press it, some get stuck when pressed in, some even get coolant inside that ruins it, etc etc. I've seen enough broken ones to know that's a common issue. Cheers.

Botha