form adjustment help

[JoJo]

After adjusting form rollers and plate to blanket cylinder pressure, I get a 2cm stip pf ink at the top of the plate, before adjustments it was 2mm and causing no problems.
I operate an Abdick 8810.. Please advice..

 

[cmac75]

How big are the stripes on the rollers.

 

[Al Ferrari]

How big are the ink roller stripes in the middle of the plate (i.e, half way around)?

Al

 

[JoJo]

upper form is 2.5 mm lower (bigger) form is 4mm. How is chech or measure plate to blanket pressure..

 

[Cornishpastythighs]

I'm not familiar with an AB Dick but have you tried resetting your settings to what they were before as you said it was not causing you any issues. You took your settings from what to what? You adjusted your plate/blanket pressure I assume by increasing/decreasing packing beneath the plate or blanket (again not familiar with the press). How did you arrive at the decision to adjust your printing pressure? It seems you have maybe re-adjusted too many things at once and now you dont know where the issue is. On a press that small it might be very easy to make a change and observe the result and then move to the next change. Good luck

 

[Al Ferrari]

In your first post you wrote this:

"I get a 2cm stip pf ink at the top of the plate, before adjustments it was 2mm".

Is that 2cm really what you meant? Or is that a typo, as in the case of "stip pf"???

The reason I asked about your stripes in the middle of the plate is that your 2cm indicates that the ink rollers are hanging down pretty low in the cylinder gap. So if your ink roller stripe in the middle of the plate are 2.5 mm, your rollers may be too hard.

I recommend that you get an experienced press operator or service man to help you on site. I suspect that the information you are giving us on this forum may not be reliable due to either poor observations, or poor writing skill. No offense intended.

Al

 

[JoJo]

I ment that I get a 3/4 inch (2 cm) bead on the lead edge of the plate while printing. The forms are adjusted to 2.5mm and 4mm..

 

[cmac75]

Back off on the 4mm to 3mm. Sounds like they are boucing in the gap on the plate cylinder.

 

[Al Ferrari]

As I indicated in my 11:03 post, that much ink on the lead edge of the plate is way too excessive.

Look at it this way: ink adheres to non wet areas of the plate. That's how lithography works. So if you were to increase the water form roller to the same excessive setting as the ink forms, so as to dampen the plate at that lead edge area, the ink rollers would be hitting a wet area and you would lessen this 3/4 inch ink build up at the lead edge.

You are probably getting a lot of roller bounce as it is, no?

Al

Edit: I see that cmac75 thinks the same.

 

[JoJo]

I readjusted the form rollers to 2.5 and 3.5mm, no bouncing anymore. But I get scumming on the side of the leading edge of the plate which soon extends to the centre, although I get very weak colors, so emulsification and scumming at the same time.

I adjusted the plate to blanket pressure and planket to impression cylinder pressure.

I suspect it is the dampening system that is playing games with me.
I adjusted the ductor roller eccentrics and tried to time ductor dwell to the fountain roller to be timed to the cylinder gap of the plate cylinder.Does this matter with a continuous flow dampening system that is standard on the abdick.

Any Ideas Please ..

 

[Al Ferrari]

It is good that you have made these adjustments, but none pertain to the water form to plate contact. I suspect that this one is marginal and that you are trying to dampen the plate with a high water transfer setting, which would explain the simultaneous scumming and emulsification.

Set an even stripe for the water form to plate by removing the oscillator roller and evenly ink up the water form roller so that you can gauge the stripe to the plate. Then clean the water form roller and attempt printing again and report back.

Al

 

[JoJo]

There is no separate water form roller. The first ink form roller acts as a dampener as well, I think your are right there is too much water because when I alter the adjustments for this roller still the problem persists.

 

[JoJo]

I remember that the last time I had this kind of problem the water ductor eccentrics needed a lot of adjustments while printing resulting in a lot of waste

 

[Al Ferrari]

OK, so this is an integrated dampening system. I have no experience with AB Dick machines and may not be able to offer much direct help.

Was there a time in the past when this machine functioned properly for you? Perhaps you are the same person posting about what sounds like the same machine in this other forum:

water trouble - Color Printing Forum

If this is you, the problem is most likely due to the inappropriate reassembling of the dampening system. Not being familiar with AB Dick machines, I cannot offer help.

Al

 

[JoJo]

It used to run trouble free it just takes a lot of time and many trials to restore it where it was. I thougnt there might be other adjustments or thing to look for regarding the dampening system.