GR 3750 color drum prints to the edge of paper

[farabundo]

Hello,

One of my GR drums (red) prints to the edge of the paper, causing a good portion of the print to appear as if it was full bleed. I'm guessing this is a problem with registration, although it has confused me that this only occurs with one particular drum. I was planning to do a maintenance/overall cleaning of my GR 3750, including having a look at the P disc, could this be where the problem originates? I somehow think it isn't, as other color drums don't suffer from this problem, so I'm a bit clueless. In case it is, does anyone have a photo handy of how the P disc should look in the correct position? I've found one, pictured below, but am not entirely sure.

Any help is appreciated.

timing_adjustment.jpg

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

Hello,

One of my GR drums (red) prints to the edge of the paper, causing a good portion of the print to appear as if it was full bleed. I'm guessing this is a problem with registration, although it has confused me that this only occurs with one particular drum. I was planning to do a maintenance/overall cleaning of my GR 3750, including having a look at the P disc, could this be where the problem originates? I somehow think it isn't, as other color drums don't suffer from this problem, so I'm a bit clueless. In case it is, does anyone have a photo handy of how the P disc should look in the correct position? I've found one, pictured below, but am not entirely sure.

Any help is appreciated.

[ATTACH=CONFIG]33816[/ATTACH]

Any ideas?

[allan]

Re: GR 3750 color drum prints to the edge of paper

If your other drums are ok i would not make adjustments on the machine.

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

If your other drums are ok i would not make adjustments on the machine.

I agree. Any ideas as to what could be wrong with the drum that would cause this?

[Iowatech]

Re: GR 3750 color drum prints to the edge of paper

Hello,

One of my GR drums (red) prints to the edge of the paper, causing a good portion of the print to appear as if it was full bleed. I'm guessing this is a problem with registration, although it has confused me that this only occurs with one particular drum. I was planning to do a maintenance/overall cleaning of my GR 3750, including having a look at the P disc, could this be where the problem originates? I somehow think it isn't, as other color drums don't suffer from this problem, so I'm a bit clueless. In case it is, does anyone have a photo handy of how the P disc should look in the correct position? I've found one, pictured below, but am not entirely sure.

Any help is appreciated.

[ATTACH=CONFIG]33816[/ATTACH]

Can you share a picture of the print defect? Sorry, can't see what your machine is doing or the output you find irritating. That's kind of important because the P disk has little to do with what you've described so far. (Heh, if the P disk was the issue, you'd have problems with every drum you possess.)

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

Can you share a picture of the print defect? Sorry, can't see what your machine is doing or the output you find irritating. That's kind of important because the P disk has little to do with what you've described so far. (Heh, if the P disk was the issue, you'd have problems with every drum you possess.)

I sort of figured that, but also wanted to sneak in an opportunity to get someone to confirm whether or not the configuration in that photo is correct, as I want to do some maintenance to my Riso in the hope of it lasting a long time. It's not a great picture, but I've attached a photo of what prints using the red drum come out like, which is a full bleed on one side (literally printing off the edge):

image1.jpg

[20gaugeO/U]

Re: GR 3750 color drum prints to the edge of paper

GR's are 20+ years old, you are one component away from not being able to fix it cause the parts aren't out there any more.

If this one drum is printing off the page I'd think it's the drive chuck on the drum is loose (stick a large straight edge screwdriver in the opening and see if it moves left and right- it shouldn't, should be locked down). Where the large pin in the back wall of the machine meshes with the drum. 2 allen screws under the drum shell. Or the drum isn't spinning internally would be another lesser option.

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

GR's are 20+ years old, you are one component away from not being able to fix it cause the parts aren't out there any more.

If this one drum is printing off the page I'd think it's the drive chuck on the drum is loose (stick a large straight edge screwdriver in the opening and see if it moves left and right- it shouldn't, should be locked down). Where the large pin in the back wall of the machine meshes with the drum. 2 allen screws under the drum shell. Or the drum isn't spinning internally would be another lesser option.

I'm constantly worried about exactly that. I can't afford a newer model though. I'll check what you mention.

[Iowatech]

Re: GR 3750 color drum prints to the edge of paper

I sort of figured that, but also wanted to sneak in an opportunity to get someone to confirm whether or not the configuration in that photo is correct, as I want to do some maintenance to my Riso in the hope of it lasting a long time. It's not a great picture, but I've attached a photo of what prints using the red drum come out like, which is a full bleed on one side (literally printing off the edge):

Thanks for the pictures. I took a look at the disks in your first picture, they are exactly where they need to be.
I agree with 20gaugeO/U, the drive coupling on that drum is likely worn out (I used to carry a drum drive coupling as car stock for high mileage GRs before they were obsolete). If you must use that red drum further you will need to adjust the size of the original to compensate.
Or, just use a different color drum that still works. You won't have red, but you won't have that image defect either.

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

Thanks for the pictures. I took a look at the disks in your first picture, they are exactly where they need to be.
I agree with 20gaugeO/U, the drive coupling on that drum is likely worn out (I used to carry a drum drive coupling as car stock for high mileage GRs before they were obsolete). If you must use that red drum further you will need to adjust the size of the original to compensate.
Or, just use a different color drum that still works. You won't have red, but you won't have that image defect either.

Sorry for resurrecting this, but I never found the part you both mention. Is this the drum chuck/coupling you mention in the photo? How can I check if something is off (the reason why prints are going full bleed off the edge of the page)?

IMG_5876.JPG

[Iowatech]

Re: GR 3750 color drum prints to the edge of paper

Sorry for resurrecting this, but I never found the part you both mention. Is this the drum chuck/coupling you mention in the photo? How can I check if something is off (the reason why prints are going full bleed off the edge of the page)?

[ATTACH=CONFIG]34722[/ATTACH]

That's the part at least I was talking about.
I'd start out with a drum that works, put a confidential master on it, run 10 to 20 sheets of paper through the machine, then open the scanner and gently try to move the drum back and forth by hand. It will move around a little bit, but as long as the drum works that's normal. Then repeat with the red drum, if it moves around more, that drum drum is worn out and needs to be thrown away.

[farabundo]

Re: GR 3750 color drum prints to the edge of paper

That's the part at least I was talking about.
I'd start out with a drum that works, put a confidential master on it, run 10 to 20 sheets of paper through the machine, then open the scanner and gently try to move the drum back and forth by hand. It will move around a little bit, but as long as the drum works that's normal. Then repeat with the red drum, if it moves around more, that drum drum is worn out and needs to be thrown away.

Will do this, thanks for the tip. Just out of interest, could I not just compare the drums without putting a confidential master on and running prints? If there's a noticeable difference and problem with the red drum wouldn't it be regardless of masters/prints? Trying to fully understand the issue going on.

[Iowatech]

Re: GR 3750 color drum prints to the edge of paper

Just out of interest, could I not just compare the drums without putting a confidential master on and running prints? If there's a noticeable difference and problem with the red drum wouldn't it be regardless of masters/prints? Trying to fully understand the issue going on.

You don't absolutely need to put a confidential master on the drums. Regular masters will work OK.
It's just that the confidential master won't waste paper during troubleshooting print job, so it would probably be best to put one on the malfunctioning red drum at least.
Most of the time a confidential master reduced the amount of ink I got on my hands, clothes and workspace during troubleshooting too.