Shinohara 75IVP Perfector Registration Trouble

At our shop we have a recurring problem with the perfector turnover drum located directly after the skeleton drum. Press is a 2009. This problem has been on going for several years now. We have difficulty registering 23x29 4 color work. All the of the issues point to area between units 2 & 3.

Grippers have been reset several times but this only fixes the issue temporarily. It seems the press quickly wears after the gripper setting and register gets out.

We have determined that changing the turnover drum cam follower helps the issue in the short term. This cam follower will get a cut in it after ~600,000-1m impressions. The cut is from the bearing riding at a slight angle against its journal. The sharp edge of the journal is what causes the cut. Once the cut is visible, fit begins to suffer. Once the cut is tangible I replace it. Yet, even on a brand new bearing, fit is not optimal. Technician indicates the perfector needs a rebuild because the arm carrying perfector cam follower is tweaked or bent in a very miniscule way.

Anyone have experience with an issue like this? Have you developed an effective work around while waiting for the rebuild service? If you had somebody successfully rebuild your perfector please send me their contact info. That would be greatly appreciated.

So far we have focused our efforts keenly on ensuring all stock is high quality and grain long. We also focus our impositions to be aimed at keeping tight registration as close to the center of the sheet and toward the gripper as possible. Finally, we have installed humidification system to maintain 25-35% RH during the dry Wisconsin winters. All this has helped but not enough on some jobs.

Any input would be greatly appreciated!

 

Update: We have decided to not do any perfecting until we get this cylinder rebuilt. We believe the action of changing to perfect is exacerbating the problem.

 

Thought I'd update with what we've found. The large pin for straight gripper in turnover drum had taken a pretty severe impact at one point. Over time it ground down the needle bearing. Lots of slop was found in the 2 bearings in the cylinder. The 3rd bearing held by the 2 allen cap bolts was not severly damaged but replaced anyway. This was replaced in frame by completely disconnecting cylinder and dropping it to the bottom of the cylinder bearing opening in the frame and sliding the pin out through there.

 

Thought I'd update this a bit. Continuing to operate flawlessly 1.5 years later. Registration issues are minimized through the perfector grippers. I'd still prefer a straight machine for straight printing but... It is what it is.

 

Did you fix it?

 

Yes. Not sure what you mean. I detailed what we did.

 

Sorry,
Regards

 

Hi Broaner, thanks for the detail on your post, may I ask you something? do you have the service password for the 212 screen?