jv3 160sp Y direction acting oddly

[artbot]

1. for the last two days when the printer is doing cleanings, i've heard a low groaning noise. i had a large piece of aluminum leaning up against it. i assumed that it was some echo of a noise coming off the aluminum.

2. do a test print (margin offset 1 inch). the print lands offset from the media's edge about -.75" to -1". yes, behind the border.

3. test a small file, printing at 360x360 one pass bi. the print staggers violently off the margin to the right losing about a half inch per pass.

4. prints next test fine.

5. with a large sheet of aluminum loaded offset margin at .38" it seems to add the .38" to the opposite side and stretches the image maybe an inch. it's hard to tell i was printing varnish.

what does this sound like? i have a rush order that i doubt can be finished in time.

6. restart the printer. print lands fine.

aa

 

[SightLine]

Thats an odd one. Almost sounds like data or encoder problems at first but I wonder if that motor is failing. As in - it has developed a single bad spot that may or may not affect printing depending on where it last stopped. As in - if it happens to stop at a particular rotation of the motor where the bad spot is - there will be a problem but - if it stops anywhere else in the motors rotation it's rotational movement allows it to skip past the small bad spot without issue.

I've seen similar issues in brush motors many times where the commutator develops a bad spot. If it happens to be at rest on that spot the motor might not start at all and simply appear dead. Manually rotate it off the dead spot on the commutator its starts and runs fine simply skipping the dead spot by the sheer speed of it's rotation. Similar issue on non brush motors where is might have multiple windings and one winding goes out.

Unfortunatley if it's that the motor will need to be replaced. Another possibility could be data but coming from a a failing componenet on the mainboard or slider board. Possibly a capacitor crapping out or something. Probably would not hurt to check the motor mounts and it's bearings as well though.

 

[artbot]

@sightline thanks for the reply.

here's a rendering of the two bad prints (tests).

i'm wondering how i can set up a protocol that will get me through this printing day. i have a truck leaving tomorrow morning that this piece needs to be on. otherwise, i'm looking at crating and buyers plotting my death.

would it seem that if the print starts out good, then i'm good for the whole 8 feet? i could put a "non-print" header/target mark at the file to get an early warning if it's going kattywonkers. ??? then halt the print before it gets going. (i print over the same piece about 7 or 8 times, one off register pass and i've ruined a week of work).

 

[MikePro]

i've been racking my brain allday thinking of things you might not have tried yet.
clearly not an encoder strip or media sensor issue. at first I started thinking you were trying to print on clear and I was like "duh, his media sensor must not be reading it" but then as I'm replying I see that you're printing on aluminum so.... crap.

still making the same odd noises now that the sheet of aluminum no longer leaning on the printer i assume?
check the operation of the belt and the y-motor? carriage-out and move the carriage swiftly, by hand, left/right.... notice any slippage? the gear of the y-motor that drives the belt is held in place by an (lol) Allen screw. maybe it's loose/worn and its occasionally slipping?
(attached pic of my old y-motor for reference)