Distorting offset plates for growth compensation?

[schenkadere]

Does anyone distort offset plates for gripper to tail growth compensation? First time I'm seeing it after all these years and found it odd for sheetfed offest.

 

[schenkadere]

Any insight would be very helpful and appreciated.

 

[SteveSuffRIT]

Has paper grain direction been confirmed, should be grain long, parallel to press cylinders.
Has press packing (thickness of plate, blanket, packing) been confirmed?
Are individual ink colors progressively changing size and not fitting, or are all images fitting but just longer/shorter?

 

[schenkadere]

Has paper grain direction been confirmed, should be grain long, parallel to press cylinders.
Has press packing (thickness of plate, blanket, packing) been confirmed?
Are individual ink colors progressively changing size and not fitting, or are all images fitting but just longer/shorter?

It was just a blanket practice to run plates scaled 99.9% gripper to tail. I don't have the history for the reasoning, I've just never seen this before.
It's not a problem, just unusual to me with CTP and aluminum plates. There's some sheet growth on press. Probably about 1/32" over the length of a 28" sheet.

 

[chriscozi]

Sounds like overpacking.
- But we make our blankets last longer !!! -

 

[Gianni_S]

Have heard something like it some years ago and collected this information… Who knows, it could turn helpful in future.

Prinect Automatic Paper Stretch Compensation | HEIDELBERG

Precise print image, even if the substrate is stretched. Discover Prinect Automatic Paper Stretch Compensation.

www.heidelberg.com

 

[schenkadere]

Sounds like overpacking.
- But we make our blankets last longer !!! -

I agree

 

[schenkadere]

Have heard something like it some years ago and collected this information… Who knows, it could turn helpful in future.

Prinect Automatic Paper Stretch Compensation | HEIDELBERG

Precise print image, even if the substrate is stretched. Discover Prinect Automatic Paper Stretch Compensation.

www.heidelberg.com

That's a neat concept, but I'd imagine it would need to be calculated for repeat running conditions.

 

[Pommyding]

Any insight would be very helpful and appreciated.

Yeah I get it all the time on our itek 3985 2c press always find stretch down one side … put it down to paper grain as we grip on the short edge, our 3304h not as much.

 

[Magnus59]

We used to have an old Speedmaster that always printed longer on the third unit, that was where magenta was run most of the time, we had to create a special plate exposure job (this was back in the Brisque days) to scale the magenta at 99.98% around the cylinder. It was easier than the operator adjusting the permanent packing.