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.

 

[Alois Senefelder]

Roller Setting

Roller Setting

Hello fellow Lithographers,


I suggest you download the PDF I posted, search for Thread: Ink Flow and Roller Setting
Posted: 12/12/2009


Regards, Alois

 

[realaqu]

we were taught by heidelberg guy, the 2nd methond is the right way to check roller settings, but usually we use the first method but make the strip 0.5mm less than standard.

 

[madjock]

I don't know how anyone else sets rollers, but I always set the form inkers to the oscillators first, then check them to the plate by dropping them onto a clean dry plate, and for checking wether or not the ink stripes are even side to side, use a Botcher stripe guide, this is much more accurate than sticking bits of paper onto a roller!

 

[1Pressman]

roller settings

roller settings

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?

SECOND METHOD BUT WHILE INCHING, NOT RUNNING. Larger rollers are heavy and definatly flex, and bounce(momentum)
Forget running paper into nip, that will add more pressure.
DISREGARD the two outer lips of ink at the out side of the stipe!! That is where the rollers DON'T contact and the ink is forced from the nips. Thus is more a measure of ink quantity on rollers. Just look at area between these 'lips'
John L

 

[Twin City Roller]

stripe deception

stripe deception

Even if you get a straight, true stripe it can be deceiving. You also have to check your durometer. Rollers that are too hard will still stripe straight, but, can cause too much pressure on the plate and really bounce in the plate gap.

 

[Servicetech]

Method 2 in your post is more accurate IMO, you can also "take a picture" of the stripe.

Take a small square of paper and place it over the stripe at each end and rub it lightly without moving it. Remove the pieces of paper and see that the stripe has been transferred to the paper. Now line up the stripes on the pieces of paper and you can see even the slightest difference in the stripe.

This will probably take too much time for most commercial shops these days but it is indeed accurate.

 

[dyctechnodude]

Clean plate to start ,roll plate to front edge exposing front edge of plate 2" to 3".Drop forms on to plate
and forward inch press 2 to 3" inches.Stop and lift forms.Roll press around to expose stripes and you
will see Forms stripes on plate plus the feed rollout from the oscillators feeding the form rollers. This procedure knocks 2 birds out with one stone. You will see the roller stripe and how the form roller is correctly or incorrectly feeding ink from the oscillators. Set your rollers to manufactor settings and always your have forms to oscilators setting set to optium because it will give your roller train a long life plus make you print better.Even inkflow is one of the keys to printing excellent work.

 

[fireplug55]

Lets try this method. If you do not have all new rollers in your press, chances are the circumference is not true. So just dropping your rollers to the plate will not be effective.
These next steps have never fail me.
1. Make sure your rollers are evenly inked up.
2. Plate is dry.
3. Now drop your rollers to a clean plate and leave them down.
4. Jog your press 1 to 2 inches and stop.
5. Lift your rollers from the plate and inspect each roller pattern. Do you see an even smooth roller image?
Do you see low spots in any of your rollers. Often there will be hollow spots or rollers that are not touching all the way accross.
6. After you get an even look to the roller pattern, drop the dampeners and clean up the plate.
7. now you are ready to stripe the rollers and see what your stripe looks like. You may need to chnage a form roller if the setting has a buldge to it or a very thin area.
Ghosting, chop marks or steaks are a sure signs of poor roller settings to the plate or distributors.

Setting to manufactor specs is fine with new equipment and rollers but in the real world how often or long do we run with new rollers before you change them. We are on a yearly rotation, that is the best conditions I have worked with in my 36 years in this business.

LAST - The mark of a good craftsman is adapting to the conditions around you, they will never be perfect.

 

[Peter R]

Heidelberg roller damper setting

Heidelberg roller damper setting

Quick method for H/berg with Alcolor.

New press - Vario off, plate inkers /ghostbusters off, ink oscillation on, plate cocking zero.

Remove metering roller/damper
Run up opaque white or pantone yellow to see stripes easier
Wind off 1st & last form rollers to oscillators 2 turns
Check inside form rollers to distributors
Wind on first & last inkers 2 turns to oscillilators & set
Set plate damper to distributor & Z to damper
Replace metering & drop rollers & dampers on plate /draw a line on bearer with a marker to align next roller drop
Wind back metering by hand & check ink stripe / wipe off with water
Lift off rollers & check inkers & damper to plate (1st inker sometimes gives a mottled stripe & isn't actually touching the plate/ check with torch for bold stripe)

Rule of thumb - set heavier to distributors than plate/ keep even across the roller/set last two plate inkers lighter to reduce roller stripes in solids/ wind adjuster on rather than off when setting/ set duct vibrator (oscillator in ths states) correctly to reduce shock marks. Lifting off is the correct method but quick check dropping is fine. Electronic method also good / diginip etc.

 

[sriraghavan]

hi
can any one of you
may explain the above said method in drawing please