Riso GR3750 wrinkled master

[copmuter]

Hey there!

My GR3750 prints well but ever since I bought there are some wrinkled marks on prints. What is causing those is ofcourse wrinkled master paper on drum and I cannot find out what is causing it. I checked if the master is rolled ok when installed in the master unit and it has no wrinkles on it, but something in a process of transforming master to drum is causing those.

I'm attaching some photos. If anyone has any advice I'd love to hear your ideas.

http://f.cl.ly/items/3I251y0E2J1c2O0b1X3T/IMG_1781.JPG

http://f.cl.ly/items/13450r1T2B3W2Z1T2R2S/IMG_1784.JPG

Thanks in advance!

[copmuter]

Re: Riso GR3750 wrinkled master

No one?

[Iowatech]

Re: Riso GR3750 wrinkled master

If the plastic spindles that go on the master roll aren't there, wrinkles can occur due to not enough tension on the master material.
Non OEM master material can cause wrinkled masters too.
Are there any issues with either the image on the master material or the lead and trail margins on prints? There's a couple of other things that can cause wrinkled masters, but one of those two symptoms usually accompanies them.

[copmuter]

Re: Riso GR3750 wrinkled master

Thanks Iowatech for reply!

Yeah I think plastic spindles might be it. Our drums are not in best shape and I noticed that spindles at some drums are a little damaged. Will look into it, thanks.

Do you maybe know how to settle the problem with separator. IWhen it separates the paper from the drum, it's apparently not moving back fast enough, so it's causing this white line, pictured here IMG_1781.JPG

Do you maybe know how to control the separator? Or is that connected to some other setting?

Thanks in advance!

[Iowatech]

Re: Riso GR3750 wrinkled master

I'm not sure if that is the separator. Most of the time when I saw the separator causes image defects, it damages the master or rubs ink along the paper causing dark lines.
Take a good close look at the master on the drum to see if the line is there.
By the way, thanks for the pictures, I'm better at troubleshooting with visual input.

[copmuter]

Re: Riso GR3750 wrinkled master

Hey, thanks for reply.

Yeah it's definitely a separator. Yesterday we did some tweaking of it with testing what the best position is, how far should it be from the drum etc. According to the tehnician manual it should be 1-2mm from the drum but that position didnt work out for us. But now I think we somehow solved this problem.

About the first problem, wrinkles of the master paper, which part of the drum exactly is "the spindles"? I'm not sure I mean the same part as you. Is it possible to point it out in a picture or something? Thanks again for all the help.

[20gaugeO/U]

Re: Riso GR3750 wrinkled master

"the spindles" are the plastic flanges that go on each end of the master roll when replacing. Sometimes there is a 2nd set in the stand in case someone threw them in the trash by accident.

Wrinkles can also be caused by the rubber black impression roller under the drum being "dog boned" on the ends, or the plastic loading mylars being bent/deformed/missing, the mylars under the clamp plate being broken, the master brake that controls one of the "spindles" rotation speed failing, the drum not spinning as smoothly as it should due to multiple issues....

You can only do so much with a 20 year old machine and no parts available.