Sheet hitting cover lays on front lays of SM74 (2008)

Hi,
Does anyone out there have this issue?
When running a 19x25 #80 coated text weight sheet I am having issues with the corner of the sheet hitting the cover lays on the front lays.
This causes the sheet to fold under at the corner and therefore crease going into the press.
The sheet size means that the edges are in between two grippers but a lot of press houses run this press and size of stock.
Any advice would be appreciated.

 

Usually, you can easily resolve this by opening up your cover height a bit. It is also possible that your cover height motor is not working or is improperly set. When going into the screen where you can adjust your cover height, make sure that the number below the icon is not blinking if you have cptronic, or is black if you have cp2000. If it is blinking or grey, this means that the motor is likely bad or improperly installed.

 

Sheet smoother?

 

The problem is solved. I had Heidelberg come out and the guy removed the two widest front lays. They don't have motors, its basically just a square piece of metal that fits above each head lay to stop the sheet going into the grippers early. I have a photo and video of what was happening but couldn't figure it out how to upload it!!
Thanks for your help though.

 

Not what I would have done, but I guess it solved the problem. Those "square pieces of metal" are actually for controlling the sheet as it goes into the head stops, not to prevent sheet from going into the grippers too early, thats the job of the headstops. As long as you run only a 25 inch sheet you should be ok. The problem could be when you run a wider sheet, the edges might want to flip up. These metal pieces actually hold the that sheet down so the grippers can grab them, now that they have been removed there is really nothing to prevent the outermost grippers from missing the sheet. Also, the actual part of the headstop that the sheet rests against is the thumb wheel. Hopefully he removed that also. That square piece of metal was the mechanical limit for this thumbwheel. Now that it has been removed there is nothing to prevent this thumbwheel from spinning all the way out and falling into the press should it come loose.

 

Why would a Heidelberg engineer remove pieces from a machine especially important items from the infeed, don't really think this would be approved by the factory.......

 

Because sometimes they don't have enough experience one day a washing machine repairer the next a Heidelberg engineer LMAO

 

Yeah, I would have to agree that taking parts off a machine that an engineer has worked so hard to make sure was there can never be a good idea. Im definitly not a fan of taking parts off of presses. Kind of surprises me that a Heidelberg guy would do that. With all their cut backs, pretty much the only guys left are the experienced guys.

 

What, then, would you have done that didn't involve altering the press in some way or ridiculing the work of someone you know nothing about?

 

It is a 2 minute job putting them back on if needed. The problem I have is a machine built to A2 and B2 specs and trying to run a common N.American sheet size on crappy stock that falls between 2 grippers. Common problem by what I have heard. Taking parts of the press is maybe not the best idea but this forum is full of suggestions that are nothing short of old wives tales by so called "experienced" people. You do what you have to do.

 

Is this a suction tape fed machine or does it have wheels on the feedboard, why not use smoothers right behind the head stops? Also, some machines have a vacuum control right by the infeed to hold the sheet flat, have you looked into that?

 

It has the suction tape.
The problem isn't with the sheet going into the infeed, it is when the sheet is gripped and taken into the press. The edge of the sheet curls down slightly and hits the square cover on top of the front stops. This causes it to fold under and then crease when it goes into the press. It only does it on very light stock that is 19x25 inches. An A2 or B2 sheet wouldn't give me this issue because it would be taken by the grippers. Any other sheet size I run is fine as is a 19x25 sheet that is thicker.

 

Ah, I see what you're saying now, yes it's a paper size problem related to whatever market the machine was made for, I assume this is a European model?

In any case, I know it's a bind but for the shorter run jobs, have you tried curling and fanning the paper down on the corners?

 

Yes, tried that but still have same issue. Its only on light weight stock of this size. If I just had that extra inch!LOL
It is a european model though I'm not sure if there is a difference.

 

have your tried to run the sheet a little off center when you get to a 19 X 25 sheet?

 

Not sure how I would be able to "cheat" the settings in Press Center but will look into it.

 

Or get your buyers to sanction running the max sheet size, is that 26" on a 74?

 

you could do this by manually moving your side guide to the desired position. Off course you would also want to manually move your delivery joggers in the same direction.