[Misc] GR3770 - Master moves on drum

[felixvie]

Hi everyone,

I am experiencing a peculiar issue with one of my GR machines that I cannot resolve.

Whenever I burn a master, it gets mounted under the clamp perfectly, and the length of the master under the clamp is fine as well. However, after a few impressions, the master starts to move slowly but steadily. After about 50 impressions, it has shifted by approximately 1-2 mm, and after 100 impressions, it has shifted by about 3-4 mm, and so on.

To determine the offset, I marked a line under the clamp with a ballpoint pen immediately after burning the master. The distance between the clamp and the line keeps increasing - it happens with any drum, not just one particular.

Does anyone have any ideas on how to fix this? I am using an OEM pressure roller with high-quality bearings, and the pressure setting is set to minimum. I'm not sure what to check next to resolve this issue.

Thanks in advance for your help!

Best regards,
Felix

[jermyth]

I hazard at the impression roller if it happens to multiple drums. You can try to reduce the amount of press it's applying but most likely it needs replaced. You can check to see if has ink built up on it and scrap it off if it does. Good luck with the dinosaur.

[Rickybobby]

It seems to me, when i had that problem, it had to do with the clamping plate pressure. Especially if it's happening on all drums. Sometimes the clamp solenoid is faulty or out of alignment.
And of course Scrape all the old ink off the pressure roller, don't just clean it.