Image wont fit on SM52

[RGPW17100]

We have an SM52 5 color with a coater. Unit 1 typically is run as a dead unit to depowder. Unit 2 (Black) seems to print too large both from gripper to tail and from OP to Gear side. I tried to remove 3 thousands packing from the blanket and saw no effect. We do not have a blanket guage and I doubt we will seeing one soon. Any ideas on a quick fix for this? It is worse on 80 gloss text but is apparent on cover stock runs as well.

 

[rbailleu]

my guess is that you have a plate cylinder that is pushed out by .002 or so. packing the blanket wont do any good. you need to pack or unpack the impression cylinder or plate cylinder. to test add .002 under the plate. see what happens I had a sm52 this happened on. I am not sure on the side to side growing. that could be bent journals.

you really should get a packing gauge.

any decent mechanic can put a gauge on the cylinder and bearers and see if one cylinder is out.

on most presses the plate and impression cylinders dont move just the blanket cylinder on an eccentric. so the blanket will ussually will move instead of bending.

 

[Paultheprinter]

Are all cylinders and journals clean, it may be excessive preasure causing stretch as the edges of the cylinders are shitted up, other than that reduce water to minimise dimension change.

 

[RGPW17100]

bearers and cylinders are clean. We put 2 mil packing on the plate and registration was much better. Money is tight so we are putting band aids on a lot of stuff waiting to place a service call when we go down. I dont want to mess with removing the impression cylinder sleeve to check packing. Our mechanic did this a couple of years ago and trashed a $750 sleeve. I will speak with the mechanic about this when he is out here again. We will only pack the plate on real critical jobs. A lot of our stuff is photo shop so the pixels being out of registration arent that noticable.

 

[rbailleu]

ours turned out to be a plate cyl. moved by .002. all that they needed to do was unscrew the cylinder and tap it back in. 2 days labor. but a new cyl is like $7000. the problem is it took them 2 previous days to figure it out. its kind of neat though they put a dial indicator on an arm and inch the cylinder arround with the needle on various points accross the cylinder. you could just see it move in and then back out ever so slightly. put a set of 1 inch grid plates on each unit and you will see which units are out.