Faint images

[Web love/hate print]

Hi Everyone I have a small offset Hamada 500 SRA4 press running bigfoot feeder and Varn and do 57000 plus impressions per month here in the uk, I've been in print for 30 years now weboffest and now home run sheetfed and not come across this problem before, when I'm printing a largest area of solid or tint every now and then part of the image prints faint like the impressions come off, it's not all over and not on every sheet, it seems to be at the lead edge only but the really strange thing is it's faint in different parts of the image not the same part every time. I've checked all setting and have 4mm strip on everything I've changed the fount and checked the idle roller is actually idling not checked the form rollers yet maybe it's that or I think maybe the cylinder bearing/gears?? It doesn't matter if I run at 6000 iph or 4000 still the same, has anyone had this type of problem? It's driving me nuts stressed out trying to sort it look forward to any advice many thanks Allan

 

[davarino]

I going to hazard a guess: the image is longer than the circumference of at least one forme roller or of the oscillator roller.

You MIGHT be able to fix this with a "jumbo" oscillator roller. If the problem is what I think it is, that is the only way out that I think of.

 

[smalloffsetpressexperts]

Pressure between forms and oscillators ok? Main Osc. in time and has full travel? How large is the solid? Provide more info please

 

[Alois Senefelder]

Hello, Experience!


30 years experience and you haven't checked the "Plate Inkers setting against the Vibrators " methinks something is wrong!!!!!!

1) Disengage the Damping rollers then roll the plate up solid and print a sheet, next roll the Plate/Blanket solid - then put the press on Impression

and check the "Dwell Line" - "Stripe" width between the Plate/Blanket/ Impression Cyl.

Regards, Alois

P.S. Post a "Good Pic." of what you are seeing on the sheet.

 

[Web love/hate print]

Many thanks for a few ideas, I have checked plate to blanket blanket to impression strip seemed ok, the oscillator sits on top of two small idle rollers I'll check this out but there is no adjustment as it's just the weight of the roller that sets the pressure, I'm a bit busy at the moment but will see if I can get some pics of the image, it' not a huge solid not even half a page, I think it could well be the rollers worn or settings even though I've checked and altered them. Many thanks Allan

 

[keith1]

Something about this seems vaguely familiar. It's been years since I've run a Hamada, or any press for that matter. But I seem to recall once having that problem on a Hamada and it seems to me the impression trip required some minute adjustment. I don't remember how to do that. Could've been something on the non-operator side.
Not terribly helpful. Just when I read it, something resonated.

 

[kdw75]

We have a 555CDA with bigfeet still in use for envelopes. Every time someone asks me for advice in solving an image problem or scumming, first thing I do is go through and check every single roller to roller stripe. I can't even guess how many times that has been to blame. It is like a chain and you know what happens with a weak link.

When this machine was pretty new, we had a wise ass that thought it would be fun to screw with the junior pressman who was running this machine, by spinning the water form bushing on the non-op side causing some hard to solve toning problems for him. After several hours of downtime, another pressman got him going again.

The junior pressman was me. I was 19 and had only been running a press for two years and the other guy was jealous because I was given a brand new press that he thought he should have been running.

 

[Web love/hate print]

Hi Guys Problem solved, it turns out the vibrator roller was sticking due to ink build up cleaned up and oiled that and I also made slight increase in pressure on the form to plate rollers sorted it, thanks for all the advice and ideas Allan

 

[Deleted member 16349]

Glad you found the solution to the problem.