RZ990 - masters not adhering to drums, misfeeds

[Guest]

Hey all,

I'm having a problem with my Risograph RZ990 where after making a new master the machine is unable to make the initial proof copy - paper misfeeds in the feed area. Pulling out the drum, the master is never entirely applied, occasionally hanging completely loose and the drum appears dry. Masters made before this problem started print fine & with even coverage. The new masters will continue to misfeed - though occasionally I can push down the loose master enough so that it sticks to the drum and then I can make impressions. . I would assume this is some sort of pump error if it wasn't happening between all my drums. I've also tried switching my feed tires and flipping the pressure roller. Is it a timing issue? Does anyone have any ideas?

Thank you!

Matt

[Iowatech]

Re: RZ990 - masters not adhering to drums, misfeeds

As you have indicated there were no print defects before this problem, the most likely issue is that there is not enough prints being made per master. If that is the case, be sure to make at least twenty prints per master, any less and the the ink feed will not keep up and eventually the masters will not stick to the drum.
If you must make less than twenty prints per master, after that run is finished sometimes pressing the "Idling" button on the left hand side of the operator panel before starting the next job can help.

[mattd]

Re: RZ990 - masters not adhering to drums, misfeeds

As you have indicated there were no print defects before this problem, the most likely issue is that there is not enough prints being made per master. If that is the case, be sure to make at least twenty prints per master, any less and the the ink feed will not keep up and eventually the masters will not stick to the drum.
If you must make less than twenty prints per master, after that run is finished sometimes pressing the "Idling" button on the left hand side of the operator panel before starting the next job can help.

Thanks for your response. I've experienced what you describe before - but now I'm running at least 100 copies per master if not more. It's happening universally across all my drums, including ones that have I have just printed off 20+ copies on. It doesn't seem like a cumulative effect from repeatedly making masters. I'm totally baffled.

[jermyth]

Re: RZ990 - masters not adhering to drums, misfeeds

Are you using RISO OEM supplies? I've seen weird problems with non-oem master.
If not a master material issue, and it's happening on multiple drums, perhaps the impression roller is not pushing against the drum or is worn down and not making contact with the drum. Are you getting prints eventually or nothing?