Heidelberg roller oscillation.

[madjock]

After about the 12th time of this occurring in the last 18 months, I thought I would ask around to see if anyone else has had the same problem or is it just me!!
Running a CD102 7 colour 1998 model, and the oscillation on all units keeps failing, the bolt that attaches the arm from the cam to the oscillator shears and oscillation stops, to fit a new bolt is a real pain and time consuming
I have had various theories as to why this keeps happening, from incorrect roller settings, which is not the case, to using UV inks, which I don't understand, and a possible design fault, all I know is that in 25 years of operating speedmasters this has never happened, except on this one press???

 

[turbotom1052]

Are you replacing the bolt with Heidelberg part? If not is it at least the correct grade bolt? You may also want to look to be sure the oscillators are getting oil.

 

[madjock]

Original Heidelberg parts and plenty of oil.

 

[junker1984]

Are the universal bearings in both sides of the arm good? That is a very peculiar problem. I've been repairing these machines for over thirty years, and occasional breakage is not unusual, mostly from the jam but coming loose and causing scoring of the bolt shoulder. Possibly excess buildup of dried ink on journals? Not likely with UV inks. Maybe worn out bushings in oscillator bearing housings causing the oscillators to skew a bit??? Do you have excess oil leakage? That may be a sign of the brass bush being worn. That's really reading, but like I said, unusual problem.

 

[madjock]

Hi Junker.....thanks for your input, the rollers are in pretty good condition, all rubbers are replaced once a year and set properly as per the manual, and I can't see any sign of wear although it is hard to tell because everything is covered in oil, one thing that does happen is the oscillations slowly diminishes to almost zero and then I have to reset it, one time all the allen screws that hold the plate with the scale on it sheared, as well as the bolt itself, very puzzling!!

 

[junker1984]

I hate to speculate...odd indeed! Has to be excessive resistance in the roller train, to shear all the scale bolts, though. Any possibility the inks are partially curing due to an ambient light source? Can the inks be too tacky? I have little to no knowledge of UV applications. Only other thing I can think of, but never seen, is the possibility of worn bushings allowing the oscillators to skew and bind. That comment may get me laughed out of the business, so be careful who you repeat it to.

 

[madjock]

@ Junker......I am puzzled by this as well, I would also think that the cause was excessive resistance, but the rollers are meticulously set and regularly checked so I would be surprised if there was any excess friction, and as far as I know UV ink only cures when is it lamped so that would not appear to be the cause either, not sure what bushings you are referring to, but if you can give me a pointer to their location I will have a look.
@Alibryan.......we always lube units that are not printing, it seems to happen in a random pattern and yes it happened before I operated the press, but never on any other speedmaster I have operated.

 

[Deleted member 16349]

Could it be that the rollers are swelling when running and then provide the higher load? Just a thought.

Maybe for some reason the stroke length is too long and it is bottoming on one side or the other. Shorten the stroke and see what happens if that is possible.

Shearing of bolts is not good and if it is not corrected, one could be liable if there is a related failure and someone gets injured. Maybe a service call is needed.

 

[junker1984]

If there's any credence to what I mentioned, you would be checking the bushings that the oscillators run in. You would have to pull all riders and forms, then grab the oscillator bodies and feel how much play is in them...not radially, as there will be a bit there inherently, but see how much you can move it up and down, forward and back and diagonally. Seems to me there was an allowable .1 mm (.004") in any direction. Keep in mind, I've had many apart in various repairs requiring removal of oscillator assemblies and haven't seen the need for replacement in those I've seen out of tolerance. Speaking of removal, is it possible that there have been repairs done on the affected units requiring removal of the driving arms...and the mechanic didn't get the arms repositioned correctly? That may cause the oscillators to stroke too far in one direction, as Erik mentioned.