crooked master or crooked paper feed?

[gillje]

Hi, I've been having a problem with my gr3770 skewing my prints.

I've tried adjusting and re-adjusting the parallelism of the timing and guide rollers but that hasn't really improved things consistently... and now after a closer look the masters appear to be sitting under the drums clamps at an angle. I put a grid stencil onto my drum and measured the distance between the edges of the screen and the lines in the stencil across the drum and it is sitting at an angle.

What could be causing this? Could it be the pressure roller? I recently tried installing a new roller, but ran into some difficulties getting it to fit (I think it was the wrong size) so I put the older roller back... Since then my prints have been offset from the lead edge by a 1/4-1/2 inch.

Another possibly related problem are that my masters become wrinkled on the trailing edge when they are being loaded.

Ok any help would be appreciated.

[JustManuals]

Re: crooked master or crooked paper feed?

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[gillje]

Re: crooked master or crooked paper feed?

Thanks, I already have the parts & service manuals. I've also asked riso directly about servicing the machine but they pretty much said no. Any techs in the Greater Toronto Area with exp with GR machines?


Ok, any advice or insight into my problem would be appreciated!

[mikadonovan]

Re: crooked master or crooked paper feed?

Sounds like you have a problem with the write roller, like a bearing is out of position or something. If it started AFTER you removed and reinstalled the roller you had better backtrack your steps. If the master is crooked on the drum, it has nothing to do with the pressure roller.

[gillje]

Re: crooked master or crooked paper feed?

ah, the offsetting of my prints from the lead edge began after I tried to switch the pressure roller, but the skewed masters have been a persisting problem for awhile, I only just realized the masters were being loaded onto the drums crooked. Up until today I thought it was an issue with the paper feed... How do I check out the bearings of the write roller? The manual describes the removal procedure for the roller, I'll take a closer look tomorrow and check back in.

J

[gillje]

Re: crooked master or crooked paper feed?

So I took off the front side cover, the write rollers bearings seem to be sitting all right on both sides, I removed the belt around the pulleys that rotate the write roller and was able to rotate it freely and it seemed to be moving pretty smoothly / evenly on both sides, but to be clear I'm not exactly sure what I was looking for in the first place.

I tightened the tension along the belt / pully G for the write roller, this seems to have improved the situation somewhat... However I don't think I can tighten it anymore and it's still a slight amount off. The pics are kinda blurry, the red drum is pre adjustment and the blue drum is what it's like afterwards. It improved about 1/8 of an inch, but is still approx 1/8 off.

Any one have any ideas about what's going on here?

riso_drum1.jpgriso_drum2.jpg

[gillje]

Re: crooked master or crooked paper feed?

Things have taken a turn for the worse,

I'm trying to reset the vertical positioning of my prints (this became offset by about a half inch when I tried replacing my pressure roller)

So I'm following the steps in the service manual, trying to get the alignment holes of the shaft plate to match the one in the cam pully, but each time I try to loosen the tension on the main belt I'm unable to move the cam pully in any direction - and then when I screw everything back together, the print becomes further out of position. It went to a whole inch and a half off from the lead edge, and now its currently so far off that it's printing about 2.5 inches of the back edge at the front of the sheet - so that's like 14 inches of the image being printed before the paper is even making contact with the drum.

oh man what do i do !

I don't want to throw things any further out of whack ! Any help would be so appreciated !

[gillje]

Re: crooked master or crooked paper feed?

Ok, I got the cam & main pulleys back into alignment, however every time i try to print they become misaligned by about 1/4 - 1/2 inch and it fails to feed any paper through. The error "Paper Misfeed Check Paper Feed area" comes up and it asks me to reset. I'm able to get pulley's aligned manually, but it just misaligns and misfeeds everytime I try to print.

[mikadonovan]

Re: crooked master or crooked paper feed?

Might be time to call a trained Riso tech.

[gillje]

Re: crooked master or crooked paper feed?

Ok I got a tech to come in, he got the gr running again. It turned out that the pickup roller shaft had come was not sitting in place properly and was kind of wedged into the machine - so it wasn't turning when the paper feed clutch would start spinning. SO paper feed problem is solved

Tech also got the timing back to where it should be, we made a master off the glass and a few copies and everything looked good. He's left and I send an image to print through my rip and it's gone out of time again! The prints are offset, which maybe isn't a huge deal

The biggest problem I'm encountering now, and perhaps this is unrelated, is that when I try to print a second colour the image skews. I print one colour and it's printing straight & fine, when I take the second colour and print it onto plain paper it's straight - it's just when trying to line them up with each other, there's a vertical skewing of the prints taking place.

[mikadonovan]

Re: crooked master or crooked paper feed?

Call your tech back. I can assure you my customers would, and I don't like unresolved issues any more than they do. Don't wait for days to call back, or you might get gigged for extra charges. If it is not satisfactory, he/she needs to know. I would have thought you would have covered all the issues while your tech was there.

[gillje]

Re: crooked master or crooked paper feed?

The tech made it pretty clear that he wasn't interested in servicing these older models. Since I'm not under a service contract, I'm not sure I'll be able to get anymore help from riso. There's a dealer who offers riso-service but they're about 2 hours away and paying a tech for that much travel time + the actual work that needs to be done might be too much for this gr

I'm really having trouble pinning down what the problem is, the timing & guide rollers seem pretty parallel, I lubricated the two springs attached to the back of the guide roller - nothing appears to be broken... perhaps it's the stripper pad & feed tires? I guess that's what I'll try next...

The reg floats back and forth by quite a lot and it skews vertically which is pretty noticeable when trying to print straight lines of text.

[jermyth]

Re: crooked master or crooked paper feed?

Is the registration floating during the print run? If that is the case then it maybe the guide roller load springs. The skewing may be from the timing roller pressure is uneven on the guide roller or the mounting screw for the timing roller ass'y has broken off. Hope this helps some.

[gillje]

Re: crooked master or crooked paper feed?

What should I be looking for when I check out the guide roller load springs? I just removed the guide roller and lubricated those springs, there's a one ways spring, and a load spring.. there's some rust around one end of load spring, and there's a bearing(?) between the springs that I can loosen with an allen key...

[SMARTECK]

Re: crooked master or crooked paper feed?

QUOTE=gillje;273855]Hi, I've been having a problem with my gr3770 skewing my prints.
I've tried adjusting and re-adjusting the parallelism of the timing and guide rollers but that hasn't really improved things consistently... and now after a closer look the masters appear to be sitting under the drums clamps at an angle. I put a grid stencil onto my drum and measured the distance between the edges of the screen and the lines in the stencil across the drum and it is sitting at an angle.

What could be causing this? Could it be the pressure roller? I recently tried installing a new roller, but ran into some difficulties getting it to fit (I think it was the wrong size) so I put the older roller back... Since then my prints have been offset from the lead edge by a 1/4-1/2 inch.

Another possibly related problem are that my masters become wrinkled on the trailing edge when they are being loaded.

Ok any help would be appreciated.[/QUOTE]



Hi my friend my name is Conrad from California. I am copier technician since 1996. I've been solve this kind of problems just replacing or inspecting the paper feed tires sometimes is the problem. Have you tried it? I hope my advice help you.