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Maho - gross positioning error Y

I had the same problem

When running in automatic - I'm running some 3.5 long, .125 wide slots - when the machine rapids down (after machining the slot at 3 depths - about 5 minutes) This alarm occurs.
I can single block, turn feedrate override down and let it start down slowly, and it won't happen.
I removed the brushes and cleaned, blew out the tacho-generator. Problem didn't go away.

Funny thing is: I have an engraving program for this same part, which is constantly up and down; runs without problem.

Control is CNC 232, Indramat 3trm2 drive

Any help would be appreciated
Sam

What my Y axis was doing (89 800 w-432-10) was sticking on a sudden rapid move downward. It would set RP next to the axis readout on the screen and put it in emergency shut off mode, hydraulics off, etc. Then I would have to fire up the control and home the Y. And it would do it again and again and again. I ran all my speeds at a much slower speed and it would not do it as much but still faluted out.

I spend quite a bit of time diagnosing the cause. The diagnostic step I took that led to the cause was loosening the the bolts very slightly on the guide plate of the vertical box-way. You have remove the brushes or you will damage them. Several large bolts and some smaller ones hold the plate on. Take a 1/4 turn loose on each bolt just to releave the presure so very slightly. DO NOT LOOSEN THEM AS IT"S THE ONLY THING THAT SUPPORTS THE TABEL :-)

I had the same problem with having to keep the machine running to make some deadlines.. This makes the machine less precise obviously but if the tolerances allow it you can get through the weekend like this and deal with the repair later. The other thing that helped out was slowing down the rapid speed in the constants. I ended up taking the rear guide plates off and scraping the ways. Very long and tedious job but it came out very nice.
The machine is happy now. I also learned that the coolant type is very important and that the turkite-like material maho uses was not tolerant to some coolants. Swelling was what hapened to mine.

I don't know for sure if you have the same problem but if you loosen the guide plates and the problem goes away, your Y Axis is sticking and most likely the binding. The tacho and possition reader (scale is doing what it's supposed to so I'm not sure that you should go there first.The surface of the material is very easy to check. is should have high spots uniform and consistent across the entire surface. The high spots are quite small. the low areas are for oil retention. If you put some machining ink or equivalent and run a precision scraper tool across and see large flat surfaces, it needs scraping.

I learned later that this is pretty common on older machines particularly if they have been run a long time with the wrong way oil and coolant. Vacra 1 is what I use. One more thing , you can turn up the oil delivery in the constants so it floods it with oil for the first 1 hour og opperation and then turn it back down.

Hope this helps. I have Kalr Reis to thank as he spent a great deal of time helping me do all. So if this helps, Thank Karl...
 
Are they available from that place in Germany that you had quote the multi-axis Maho table?
Heard back from MMD in Germany today... 224 Euro each...which is about $300...so with shipping they would be more than DMG. :rolleyes5:

Will post what Gortite quotes eventually..
 
It's fixed!
Turn out to be the oiling.
DMG never have called back.
We have checked, indicated, cleaned, adjusted etc.
The more we did, it started wandering after stopping, then later, stick-slip.
We removed the way "clamps"- cleaned back of ways and stoned off the clamp and the turcite just enough to evenly discolor.

There was a fair amount of dried oil/coolant lower than the area the wiper cleans- and maybe the turcite stuff had swelled some. (Karl Reis said that was common, along with the diff/ ballscrew mount loosening up - and mine was)

Thanks for everybody's help!
As always a great forum
Sam
hello Sam,
i have exactly the same error woth maho 500w that you described in the post regarding the y axis not keeping position and showing error GROSS POSITION Y C
(heidenhain cnc 232)
if i understood correctly you solved taking apart the cover and cleaning the ways from oil residues or there is something more to do?

thanks a lot in advance for your help,

Enrico
 








 
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