Best method to check roller stripes

[cmcfarling]

I've read about two different ways to check roller stripes. One way is to ink the form rollers while not in contact with the plate and then drop them down on the plate. Next raise them up and measure the stripe.

The other way is to engage inked form rollers on the plate, run the press for a few minutes, stop it, wait a short time and then raise the form rollers. From there measure the resulting stripe.

You could think of it as positive and negative methods. Is one method better than the other?

[nhprinter]

One way is to ink the form rollers while not in contact with the plate and then drop them down on the plate. Next raise them up and measure the stripe.

I've never heard of doing it any other way than this. I'm not really sure why anyone would want to do it any other way. Maybe it's one of those things that's been over analyzed.


Dave

[Cornishpastythighs]

Only method I have ever taught or been taught is to run ink on the rollers for a few minutes to get the rollers up to temperature, stop press and drop rollers onto plate, raise them off and observe/measure the stripe they leave.

[BillJ]

Actually the second method you listed is a more accurate way to do it. When you engage the rollers, they tend to over travel their natural position (depending on the linkage and the press). It is also the only way to stripe intermediate rollers. Try both and see if there is any appreciable difference on your press.

[RGPW17100]

Form rollers should be down and then stop press. Best to do it when inching in continuous motion. Dropping the forms onto the plate can create a shock which will make the roller appear larger. Checking form to ocillator or to the intermediate I like to use a sheet of coated stock and stick it to the roller then peal it off. Easier to measure the paper and also easier to check to see if the stripe is parallel from gear side to operator side.

[Mike Herndon]

Form rollers should be down and then stop press. Best to do it when inching in continuous motion. Dropping the forms onto the plate can create a shock which will make the roller appear larger. Checking form to ocillator or to the intermediate I like to use a sheet of coated stock and stick it to the roller then peal it off. Easier to measure the paper and also easier to check to see if the stripe is parallel from gear side to operator side.

RGPW and BillJ are correct, this method is much more accurate and precise. We set all the forms including the water form on our SM's this way. Press should not be cold, drop the forms to the plate and let the press crawl, inking up the plate. WATCH THE PLATE and see how it inks up. This is a very good indication of how well your ink forms are set to your distributor rollers. If you see the plate ink up unevenly you probably have a form incorrectly set to a distributor or maybe one of the pneumatic pistons used to drop the forms is starting to go bad.

Using the piece of coated stock method RGPW describes for checking the stripe is also the most accurate way to measure the ink stripe. Do each side of the roller, then hold both pieces of paper side by side and line up the stripe. This will tell you if it's even and the correct thickness. Much easier and more accurate than holding up a stripe gauge covered in yellow ink to an ink form to see if your close.

Mike

[nhprinter]

The original question I believe was more for the ink form to plate adjustment. If you run ink on your plate and then raise the forms the stripe is going to be effected by the amount of ink on the plate and if there is any "kick-back" from the gears depending on the age of the press. Dropping your forms on a clean, dry plate is the most accurate way of measuring the pressure of your ink forms to your plate. There is no "shock" when you drop the forms on the plate unless the press is old enough to have a manual handle to drop the forms such as an old K series Heidi.

[BillJ]

If you let the roller rest on the plate before you inch it there will not be any kick back from the gears when you inch. When you stop inching the press may kick back but not enough to effect the stripe as long as you inch for more than a second or so. As a former press tech that was the way i was taught by the manufacturers to do it right.

[povertycow]

I have seen rollers that contact the plate when dropped down and when inched forward they don't touch anymore. I have also seen no difference at all. No one press is the same. Warm up the rollers. Try it both ways. Some presses it won't make a difference, others it will. Then make the choice that works for that press.

[turbotom1052]

by following method 2 you have the ability to check and adjust many more times as the old roller stripes get rolled out and the next roller stripes become visable. Its a little harder to see but it gives you a clean canvas to check on every time. there is another option that i frequently use that tells a more detailed story. At times i like the drop the rollers on a clean and stationary plate then with the rollers still down i inch the press a couple of inches. I then take the rollers off the plate and observe the stripes. for each form roller you will have 2 distinct stripes that shows the rollers pressure to the plate. In between the 2 stripes you will see an inked plate. If the inked plate is breaking up in between the stripes you will know that there is a lack of contact to the vibrator rollers. It wont tell you if there is too much contact to the vibrator but it will show a lack of contact.