plate cylinder drifting forward on it's own?

[Bill Rothwell]

I have a Heidelberg 6/c sm/cd 102- 2004. when you make ready the register holds, but when you begin to run it will drift forward about 40 points on it's own on units 3 and 6 only. Also during a run if you move units 3 or 6 it will lock in and then drift a little later again. Has anyone experienced this? Heidelberg said that the engineirs said it was the clamps and rebuilt the clamps in unit 6, but we still have the same problem! It wasn't the clamps. This is driving me nuts because during short runs by the time you look at the fit and find that the cylinder has drifted the job is almost finished. Any thoughts or suggestion would be greatly appreciated. Thanks, Bill

[Cornishpastythighs]

Sounds Electrical to me

[Al Ferrari]

Sounds Electrical to me

Please explain how an electrical malfunction could cause this problem.

Al

[Cornishpastythighs]

Possibly getting an intermittent signal, computer board going bad, computer board overheating. I am a printer not an electrician I have seen some computer driven motors do some funky things when they get the wrong signal. Heidelberg dont seem to know either do they?

[Kaoticor]

Is the difference showing up on your display? Or does it move without indicating that it has moved.

Another thing: maybe good to check your blanket/packing thickness if you have changed those recently in those units.

[Bill Rothwell]

the movement of the cylinder does not show on the screen, nor does it show on the pot at the motor of the unit. I hooked up a meter at the motor during a run monitoring the pot and when the cylinder moves it dosen't show that it moved on the pot (potentiometer) therefor, it looks like the cylinder didn't roll, but it is moving. Another strange thing that happens is if the unit rolls forward during a run and I roll it back to put the marks back into register it will then stay, but the very next job i put up, the first pull will show that the unit i moved back is 40 points beyond the rest of the colors on the register marks and then must roll it back down. This is really weird stuff! Thanx again for listening to my plea, Bill

[junker1984]

Hey Bill - The issue you posted is most likely wear in the pin/bushing configuration on the plate cylinder double gear. This is real common, and not real painful, you may even be able to accomplish it yourself with a little guidance. Send me an e-mail, mqgpress@aol.com. Regards, Steve

[Bill Rothwell]

Thanks for getting back to me guys! I'll shoot you a email Junker1984. I'll keep you guys posted on how I make out fixing this problem. Sounds like Junker1984 has the answer!
Bill

[turbotom1052]

some speedmasters have 2 different positions that the pin can be engaged. you might want to try the other engagement position just as a test before getting in too deep. The other thing you may want to check is the bolts going around the cylinder circumfrence just inside of the gear. Be sure they are reasonably tight. Sometimes guys will tumble the cylinder to fit a job on a diffent sized stock and not tighten up the bolts enough when putting it back!!!

[junker1984]

turbotom has a point, sometimes it's best to look at the simpler possibilities to resolve a problem. On that note, another thing to look at would be searching out the grease zerk on the outer plate cylinder gear face and give it a couple squirts of premium synthetic grease. Once the damage (wear) is done, no amount of grease is likely to help, but it's worth a try.