QM46 PU2 Scumming on one side.

[inky]

I have a problem at the moment where the non-operator side of the machine scums on PU2. The problem only starts after about 2000 impressions. The rollers are new, the machine is level, and when the problem occurs I can see fount in the tray so I assume my bottle hasn't got an air lock problem. I have checked all my roller stripes, I can't see anything strange.

As soon as the plate scums at the side and creeps in to the sheet I have stopped the feed and looked at the plate from under the feed area and the plate appears to run clean again. I'm confused by this as unless I wash up and start from scratch the problem just keeps coming back. I did think I had found the culprit as I noticed a build up of ink on the tail end of the plate on the non operator side of the machine where the plate appears to not have clamped flush to the cylinder, I corrected this but the problem still came back.

PU1 prints perfectly.

I'm really puzzled, any ideas as to why this is happening would be much appreciated.

 

[Al Ferrari]

When you check stripes, do it for all roller nips, not just forms/plate. Be sure to check the roller/roller stripes on that side in the water system as well. Check it for all the preceding units. It could be that there is lack of moisture from the preceding units, not just the scumming unit.

Al

 

[Deleted member 16349]

I have a problem at the moment where the non-operator side of the machine scums on PU2. The problem only starts after about 2000 impressions. The rollers are new, the machine is level, and when the problem occurs I can see fount in the tray so I assume my bottle hasn't got an air lock problem. I have checked all my roller stripes, I can't see anything strange.

As soon as the plate scums at the side and creeps in to the sheet I have stopped the feed and looked at the plate from under the feed area and the plate appears to run clean again. I'm confused by this as unless I wash up and start from scratch the problem just keeps coming back. I did think I had found the culprit as I noticed a build up of ink on the tail end of the plate on the non operator side of the machine where the plate appears to not have clamped flush to the cylinder, I corrected this but the problem still came back.

PU1 prints perfectly.

I'm really puzzled, any ideas as to why this is happening would be much appreciated.

I have seen a similar thing happen on a web press. It also tended to scum on the "gear side" of the press. I was thought to be due to a higher temperture on that side of the press than on the operator side. The higher temperature evaported the fount solution at a faster rate there and that resulted in early scumming. If you are having the problem on only one unit, maybe there is a bearing or something going and causing a temperature increase on one side.

Just a thought.

 

[amsman]

QM46-2 Dampaning Issue.

QM46-2 Dampaning Issue.

Al is correct, check all the roller settings in PU2, I would bet it is on the non opertor side as well.

The damper setting should be on 1 at all times.

There is a bearing on the side of the damper unit that fails due to no oil and lots of water, this also could

have happened if the scuming happened quickly.

The roller adjustment on the QM42-2 is tricky as they are moved by different colour cap screws, they oscillate ( unlike GTO Rollers ).

Go by the Manual if you have one, study it carefully.

Hope this helps

 

[RGPW17100]

Water nipple on the bottle or the water tray is deformed. See if you can remove the rubber insert to the water nipple and try again. Sounds like the water tray is running low and the water bottle is not replenishing it. If it is a stripe problem dont waste your time on the ink train chances are it is the damps. When the toning happens go to special features 02 and push minus to disengage your ink rollers while the press is running. See if the toningg goes away.

 

[Albert Noel]

we've had this issue before on several occasions.

both times within the last year it was was a bad bearing. but in the past it's happened when an op would just have a form to osc. setting wrong. i would pull your rollers and dampening unit and check all the bearings and then reset according to the book.

 

[otherthoughts]

Printing with a gravity feed bottle describes, perhaps a real(albeit older) press. As a rule most bottle fed printing units(duplicators) are subject to differentials from one side of the pan to the other side of the pan.

However, washing up would not alter this factor. Washing up does indeed eliminate extensive emulsification in the ink train regardless of side of the press.

otherthoughts

 

[inky]

Thanks for all the replies.

I have to put my hands up to this one, after checking all my roller settings again, there was no stripe between second form to oscillator, how I did this I don't know.

 

[matthew_willmer]

Hi,

We have had the same problem, and like you I couldn't work it out until the other day... the plate would look clean however we would get a tone creeping in down the Op side. Watch your bottle on PU2, because the whole of PU2 moves & the angle stops it from contacting the pan. The best way to do this is to have the press on impression for 400 sheets + (or until you get the catch up) stand at the back. Get another person to press the stop button and watch as PU2 lifts & the water bottle dispenses the water it needs in the pan.... Its a problem for us & have no idea how to fix it, but at least you know what the cause is.

Cheers
Matt

 

[kbd627]

How old is your bottle cap?? Used to have an older one w/o the plastic on the tip. They would wear down that's why Heidelberg added the plastic. I ordered a new cap back then and it had the plastic on tip. If your cap has a metal tip try putting a penny in the tray under the tip so it doesn't stop flowing. If this solves the problem then you need a new cap. As far as roller settings (you probably know this) set to distributor first. When setting to plate 2nd form 1st as this effects 2 and 3.

 

[Shropshire Printer]

Have you made sure that the press is level? Our QMs are on an old wooden floor and occasionally they will settle slightly out of level, causing one end of the fountain roller to sit too high in the fount. For some reason it only seems to affect PU2, or at least the problem is apparent there before PU1 is affected.