Oscillator Timing

I believe my oscillator timing is off on my QMDI. I read that units (from Feeder to Delivery) 1 and 2 should be at 6 o'clock unit 3 at 12 and unit 4 at 7. Should that be at a press angle of 0 degrees or the angle the press takes after i've idled and hit stop (approx 215 degress)?

Also Given that the timing is off, how do I get it back?

 

It's on zero degree. I inch the press to zero degree, decouple the rollers by intending to image a plate by aborting the procedure. Then I manual rotate the disc's to the position they need. Then start to run the press idle the rollers are coupled and inch again to zero degrees to check.

 

sweet deal. Mine are at 6,10,4 and 4! What problems do you think I could attribute to this? Poor colour consistency and toning?

 

Actually could I just confirm with you that when referring to unit 1 we're talking about the unit above the feeder and that reading from unit 1 to 4 they should be set to 6, 6, 12 and 7? (I only ask because both my presses have units 3 and 4 set to 4 o' clock at 0 degrees and they are the two more similar units in roller structure)

 

Unit 1 is indeed the one above the feeder. There is a hole in the disc that should match with a hole in the frame 6,6,12,7.

 

awesome. Thanks Marc.

 

To answer your question as to whether or not it will cause print related issues... Yes it could. In text related jobs it is hard to tell, but in large screen builds or full sheet four color work you will notice it.

The roller oscillation is not so much the issue when you are out of time but the ductor timing is. The ductor is controlled by a cam which runs behind the oscillation track cam. It was designed to charge the ink rollers during the plate gap. This enables a fresh layer of ink to always start at the lead edge of the sheet. If the timing is out you could have a fresh layer of ink coming down in the middle of the sheet or the tail end. In effect the balance of ink throughout the job could fluctuate.

In my experience most people do not notice their ductors are out of time. As I stated earlier it only shows up in certain types of work. The problem I did usually hear customers complain of was having to constantly adjust their ink throughout the run. That is typically an indication the ductors could be out of time.

 

I too was adjusting my ink constantly throughout the run. Its been better since I adjusted the timing but its still not great. I'll run for 300-400 sheets and then the densities will start to rise mostly in units 2 and 3 from 1.31 to say 1.40 for example. I was wondering if maybe I had a clog or bubble in the chiller?

 

Do you run A Classic, Plus or pro Model.

 

One classic and one plus. The plus needs some work though.

 

I had this with a classic, when the cooling unit came in I could measure a drop of 0.1 in density until the cooling unit switched of an density would rise.

 

I guess thats when they put the reservoir on the plus? Is there much I can do about it or is this pretty much ace's for the classic?

 

The tank was added for that very reason. You could put a tank on the Classic but there would be no temperature guage in it as on the Plus and the Pro. That being said if you had the output of the cooling unit going into the tank it would soften the shock of cold water going directly into the press as the tank would be a buffer.

If your cooling unit runs all the time from the room being above 74 degrees the buffer tank would make no difference as you would be pumping cool water in the press constantly.

 

Hmm.. I'll keep that in mind.
Actually on the subject of chillers, I see that there are two Flow Control Valves on the DS. one before the Fountain Rollers and when after, should they before fully open or only partially open to create more pressure on that side?

 

All should be fully open.

 

cool, thanks.

 

Can you explain what you meant by the"ductors are out of time" and how do I set them? Working on SM74-6+L.