HELP!! CD 102 Double Image

[Olie]

New to the forum and I found it informing. I hope some one can help.

I'm running a SM102 CD 4+L and getting a double image between the second and third units. When running units 1&2 every thing is ok and 3&4 by their self are ok. When running all 4 units there is a double image. I'm new to the CD format and not sure on the gripper settings. I had a talk with Heidelberg and thing it is the 3rd unit Imp. cylinder. I put a dial gauge on it and can not get any movment on it. I've checked over the transfere grippers with a feeler gauge and found some lose ones. As for the Imp. cylinder I'm unsure how to adjust them. I went under the press and checked them and found a few bitting heavy and a .001 differents between the two. The only job that was ready to run tonight fell out so I can't check it. Hoping to get some help. Thanks Olie

 

[gordo]

Assuming it's doubling and not slur, these two pages may help:
Quality In Print: Doubling
http://qualityinprint.blogspot.com/2008/12/doubling-decision-tree.html

best, gordon p
my print blog here: Quality In Print

 

[Olie]

Thanks for the reply Gordo and it is a double from head to tail moving across the cylinder.
I put the dial gauge back on and got a bigger pipe and pulled close to the top of the cylinder and I'm getting a .0025 movement. The same amount that is visable on the sheet.

But I'm still interested in any information on the gripper settings on a CD 102

thanks again Olie.

 

[rbailleu]

do the gripper have any PU left on them. It could also be gripper opening and closing timing. have you checked your cam followers.

 

[otherthoughts]

If the doubling is alternating back and forth from one sheet to the next predictably. By that I mean every other sheet prints identically, and the sheets interlacing them also print identically? Then the Double Diameter drum is likely the source of your doubling. Or in other words, if you sorted every other sheet into separate piles, the sheets in each pile would be printing similarly. Only the double diameter drum can cause a predictable alternating double.

Inspect the Double Diameter drum surfaces closely for any debris, especially near the gripper blocks and along the cam followers accordingly. I have encountered this type of doubling myself from a small piece of foam used to prevent scratching, stuck to only one side of the double drum.

A larger gripper bite at the head stops also minimizes this type of doubling.

otherthoughts

 

[Bret Hesler]

... a double from head to tail moving across the cylinder. ...

I'm not sure which direction the dots are moving based on this comment. If it is a side to side double, bearings are the most likely culprit on a CD. I think they are called thrust bearings, but I have seen them replaced many times on the four CDs we had.

Bret Hesler

 

[REYES1377]

It can also be bad thrust bearings on the back cylindr.

 

[Darth Cantu]

It can also be bad thrust bearings on the back cylindr.

It could also be his redundalator going bad

 

[Luther]

I'm not sure which direction the dots are moving based on this comment. If it is a side to side double, bearings are the most likely culprit on a CD. I think they are called thrust bearings, but I have seen them replaced many times on the four CDs we had.

Bret Hesler

I agree with Brett 100%
Try printing one color on the unit in question with the rest on impression. run some paper and vary the speed of the press. pull sheets while doing this. it will only take about 500 sheets to do this. You will probably see less doubling at lower press speeds and will worsen when changing speed upwards. Make sure you color bar has a slur target on it to see direction of movement. Thrust bearing.

 

[SpeedKing]

yup,Thrust bearings.