Maho - gross positioning error Y

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

This alarm occurs

Click to expand...

What is the alarm number and what is the description for same in the manual ?

"gross positioning error Y"
the subject of this post
No mention in the manuals, at least I haven't found anything.

Try giving the machine more lube. If it has the ability to program a lube cycle insert that into your program. Maybe the table is sticking and causing the servo to lag on the Z move. Also if ther is a prociedure to set teh drift or gain for the servo drive do that as well.
Cheers Ross

Setting the gain was something I was trying to figure out, couldn't find it in the manuals (yet- I'm having to run this thing WAO this weekend to meet a deadline, and now, with this happening, not much time for reading)

hello Toolmkr,

How did you clean the Tach? It should be done with the axis moving at say 50%. Use 300 emery paper or big eraeser polish the commutator. Then flush with electrical contact cleaner. If you cleaned it will it was not moving you could have put a flat spot on the com and when moving at a rapid it causes the brushes to bounce.

Which scales does your machine have Heidenhain or phillips? Are they clean? If you have had one off it must be parallel to the axis within .0004 end to end.

Check the machine for mechanical back lash. Could be the thrust bearings need adjusting?

Have you recently made gibb adjustments? Could be the axis is to tight.


Regards
Deckeldoctor

A couple of new observations:
It only happens in Y+ (table down)
Once the engraving got going, it started happening with that program as well. I programmed the feed about 3X greater, turned the override down, thus slowing down the rapids, and was able to run auto.

Now it seems that the problem occurs only when the table is in the far Y- (table up almost to the limit). Those programs I ran over the weekend ran perfectly this morning with the tool offset about 2" longer.

I would guess that wear on the slides is making the movement tight in the areas where the table rarely runs. Some time spent measuring the ways might give some clue. Also set an indicator to measure the "rock" of the vertical slide. Run the table right and left to the extreme travel limits with an indicator on teh top outside edge of the vertical moving element. The total indicator reading will show the table rock from the shift in table weight. Measure this effect at various heights on the machine right up to the problem area....bet you will find some difference. (tightness at the less used spots, full up and full down) Also some coolants or way oils can affect the Turcite used on the ways, or the material can come loose and move causing some wedging. If the problem is most likely when the table moves (rapid) down suspect the slide is tight in that spot, and the screw rotation gets ahead of the actual slide movement. Worn ball screw will contribute to this "delayed fall of the slide"
Cheers Ross

It makes perfect sense that I'm on virgin ways, and the table is sticking; screw out running feedback.
DD suggested maybe someone had snugged up the gibs in the area where it was used most often. That would definately do it.
Longer tool or taller vise jaws are the quick fix.
On my next maintenance session, I'll remove bellows from Y axis and check some things out.

Which leads me to a question I've asked before in another post:
Can I purchase new bellows? (way covers)
If best cost/availability option is to buy something close from mc master-carr, I'll just go ahead and do that before I remove the old one.
Thanks,
Sam

I would try FPS in Germany. They have good stock of parts for the older Deckels and they say that they service Maho as well. You will need a serial number and hopefully a part number. (may try to get a parts manual from them as well.

http://www.fps-service.de/index.htm

I always use the Fax to contact them. Their response to an e-mail seems weak at best....
I would see if they can supply all the wipers on teh machine most important of course is the vertical wiper...These need to be changed on an anual basis if you wish to preserve the ways. (they take a beating on the column)
Cheers Ross

I don't think you'll find suitable way covers at Mc Master Carr. You can get suitable material for way covers. I made the small one for my FP1 but it was a LOT of work and requires access to a heavy commercial sewing machine.

Chris P

DMG has way covers for Deckels...why wouldn't they have them for Maho as well ?

I have the impression that FPS doesn't support Maho's at all. I asked them some questions about my 1990 Maho MH500e2 and they knew basically nothing and had nothing for it. (keeping in mind that I am now an official "customer" with them and they would be more inspired to try and help me that a new prospect)

Don:
You might be correct about the Maho/FPS thing. I have also been a paying customer with FPS (have had an open account there for the last 9 years or so) but since i don't own a Maho i don't have any personal expirence with getting parts for that marque. I am only going off what they say on their web page....My sense is that DMG does not support the older stuff very well, but i will say they have always had the parts i needed for my control (not a great test as my parts requirements from DMG have been very limited)

Has anyone had success with the DMG online shop?
I cant get it to work right. Even after registering and all, my computer will lock up trying get info from it.


In their demo loggin they list these machines (just samples):
CTX 600 E 01190000251 inaktiv

CTX 600 E 01190000311 inaktiv

GD160-42 0429731 inaktiv

GD160-42 0440401 inaktiv

GDM 125MC 0481511 inaktiv

GDM 125MC 0481571 inaktiv

MD20SHAFT 0540004 inaktiv

MD7IT-4A 0541824 inaktiv

MD5S 1017344 inaktiv

MD10S 1030194 inaktiv

MD10S 1031504 inaktiv

MD20S 1031824 inaktiv

MD3IT-4A 1046554 inaktiv

MD5IT-4A 1053164 inaktiv

MD7IT 1083284 inaktiv

MD7IT 1083294 inaktiv

MD7IT 1083304 inaktiv

DMU 125 T/P 10980000143 inaktiv

DMU 200 T/P 10990000613 inaktiv

DMU 200 T/P 10990001643 inaktiv

DMC 60 U 11000000383 inaktiv

DMC 60 U 11000684823 inaktiv

DMC 80 U 11010000053 inaktiv

DMC 80 U 11010000063 inaktiv

DMC 80 U 11010000073 inaktiv

DMC 80 U 11010000373 inaktiv

DMC 125 U 11100000673 inaktiv

DMU 80 P HD 11170000713 inaktiv

DMU 125 P HD 11180000283 inaktiv

DMC 60 U HD 11190000233 inaktiv

DMC 60 U HD 11190000253 inaktiv

DMC 80 U HD 11200000183 inaktiv

DMC 125 U HD 11210001153 inaktiv

MD20SHAF 1790014 inaktiv

FP 3 22010049622 inaktiv

FP 3 22010052682 inaktiv

FP 4 M 22030078272 inaktiv

FP 5 NC 28060008332 inaktiv

CT 40 3091611 inaktiv

CTX 400 3101421 inaktiv

CTX 400 3103081 inaktiv

CTX 500 3153601 inaktiv

CTX 500 3153631 inaktiv

CTX 600 E 3155131 inaktiv

CTX 600 3611971 inaktiv

CTX 600 3611981 inaktiv

NEF 1020 3696634 inaktiv

MD20SHAFT 5040004 inaktiv

MD7IT-4A 5041824 inaktiv

DMU 50 V 5501534 inaktiv

MC 600 681053 inaktiv

DMC 60 U 684793 inaktiv

MH 800 P / MH 800 M 827454 inaktiv

DMU 80 P 859523 inaktiv

DMU 80 P 859933 inaktiv

PS.

I get it to work now, but it is tedious. And the prices are shocking.

but since i don't own a Maho

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There should be a after that statement, not a smiley ! You need to savor the varied iron fruits the world has to offer my man !

I have read a few posts about the service, or lack of, from DMG.

When I first tried to set up communications with my machine; couldn't get it quite right. I could see that the program was being read by the control, but got various alarms (none of which could be found in any doc. I have).
I called Heidenhain first, then DMG looking for a stop code (seemed to be the problem).
They both were extremely helpful. Some of the errors I received- I know I caused by fiddling with the comm. parameters; but since they were nowhere to be found in the manuals, I asked about them too.
The guy at DMG couldn't find them either, but said he would find out for me, because it was his job to do so. I told him not to bother, but he did offer.
Maybe they read this forum and have realized they dont have a very good rep among older machine owners, maybe it's good luck for me (for once), or maybe they know some of you guys are the competition.
They promised to call back about the way covers tomorrow, sent account stuff today.

You fellers do have a sweet sounding female make the first contact when you need something, don't you? Arm her with some (not all) of the info she needs, that way you can eventually get on the phone.

"Older machine owners"
I'm an older owner, and have older machines.

Heard back from DMG today, $222. ea. (need 3)
10-15 days from Deutchland.
RUSH: 4 days, add $250.

At $666 for all three you'd probably be blowin about $150 over what you could get them made for somewhere, but $150 not worth the hassel (supplying them with drawings, etc) so might as well bite the DMG bullet.

Plus you'd be joining the ranks of us rarified gents with DMG "accounts"

There's an issue.
What is it with the instant credit app.?
I never asked for credit, they kinda shunned the idea of cash or whatevercard.