print length

why does the first two units print a fraction longer on a 5/28 2004 lithrone, I've also had the same problem on a 1998 4/28. I have tried different blankets, inks, blanket tension and checked plate - blanket plus blanket - impression.
any ideas anyone?

 

Add a 0.05 underpacking under the blankets.

 

When was the last time you had your bearer pressures checked difference in pressure is most common in small fit issues.

 

same prob

the 526 i run first unit back pressure is set on dials lighter than paper weigh and 2 unit slightly harder ( i know the pressures need calibrating to the dials but the dials are well past it)

 

make sure packing on plates are all the same,if your using perma pak ,try mounting a newer one on those units.perma paks also vary in thickness a bit
blanket packing is not always precise they vary a tad.
on problematic units try backing off cylinder pressure by.002 on dial....
1 more thing you can try is to remove .002 form blanket packing and adding it to the plate, this will give you the longer print lenght your looking for.
........... good luck

 

What about plate that mounts to cylinder..semi apc

 

That seems excessive.
What about back pressurex

 

Two Questions,
Do you have a packing gauge?
Are you running short grain stock?

 

Yes John i use a gauge..also torque blankets..long grain

 

two common causes for small variations in print length can be; 1 excessive water can cause the paper to swell and cause the next unit to print shorter than the colors already down, 2nd large solids printed with a high tack ink can cause the paper to stretch when it is being pulled off of the blanket. Put these two problems togather on a text weight sheet and you can be talking up to .005" stretch over 20". Just something to think about after you check all of the other things the other posters pointed to.

 

0.05 mm, not inches

 

Note..running uv with interdeck curing in 2 4 and 6..hybrid process pms uv..i need feedback on a good blanket..thanx