Rollers

Printing

If you want to be able to solve problems fast then you'll need to understand how the roller system works. Once it's set up properly then it will give millions of trouble free impressions and produce good image quality. Remember that it's the rollers that are doing all the work and are the whole purpose of the press, to put ink on paper. Set up is in the manual and is well described and fairly straight forward to follow. There are one or two other things that I have done to improve the print quality that I will describe.

The four form rollers are the contact point between the inking system and the plate. These four rollers therefore determine what the print quality is like. The pressure between most of the other rollers is not adjustable because their sole purpose is to transfer the ink from the ink duct to the forms and mill it to a thin and even film. The other rollers also provide a reserve of ink that is available to the forms for printing large solids. On smaller presses they do not have the roller power to produce solids and that's why they run out of ink part of the way down the sheet. On the Speedmaster all of the rollers are a different diameter which helps to reduce the lines in the printed image as they run out of ink at different times. All four forms are fed by two oscillating rollers, with forms 1 and 2 having a piggy back connecting rilsan roller. The oscillators are the key to producing large solids without bar lines. On the side of each printing unit is a door, inside that is the control for adjusting the oscillation. You have an infinite amount of adjustment during the whole 360 degree cycle, but for convenience they are split into two sections, white and red, and they are split into six, making twelve in all. When printing standard jobs the best settings are white four. This will give good damping and even distribution of ink, however, it will give a bar line at about 2/3rds sheet in a full out solid. It is possible to 'steer' the ink towards to front or rear of the sheet by moving the oscillators. When printing a difficult solid it is an option to print a double solid, one of the same plate on each head. If you choose to do this then change the oscillators so that one Unit is on 1 white and the other is on 1 red. This way they will be 180 degrees apart and one unit will ink the top of the image and the other will ink the bottom. This will cut down on drying problems and will give a bar line free and dead even solid.

When printing a one colour job it's best to switch off the oscillators on the unit that is not being used. To do this, un-do the nut and move the arm into the centre of the disk, this will give a zero oscillation. It will reduce the amount of heat produced by the unit. Remember to switch it back on before you wash-up.

Set-up

The bead lines on the form rollers are set at 4mm, the recommendation that the book gives. I have found that if you set the form-to-oscillator bead line to 5mm and the form-to-plate bead to 3mm then the forms are given more drive and spin at a more consistent rate, even through the oscillator change of direction phase. It produces more heat but gives much better printing results. This is not recommended for a set of new rollers. Bed them in at the standard set up and then at about 1million impressions re-set the bead lines.

The form rollers sit inside a mount that is fitted to the chassis of the press. This mount provides the adjustment that moves the rollers to set up the bead lines. Although the fit is good around the bearing, the fit is not very good from side to side. This allows the form roller to move from side to side as the oscillator changes direction. This change of direction means that for a moment the oscillator and form roller are stationary against each other and then the oscillator suddenly moves as it starts back on it's journey across the form roller. It the form roller has movement in the mounts then the phase is enlarged and will aggravate the problem. The problem produces a bar line that will be visible on the printed image. It is, therefore, essential that the form rollers fit the guides as accurately as possible. Heidelberg produce different size shims to prevent movement. First you must measure the amount of play using a feeler gauge and then remove the roller from the press. Once off the press, remove the bearing (1) from the shaft (3). Fit the correct size shim between the two and replace the bearing. This should keep the forms still during the print run. It is also worth saying that the eccentrics should be switched off. I think they only put that feature on the press because the competition has them. I have never used them and have never felt I have had to.

Maintenance

The rollers collect all sorts of rubbish that the clean up doesn't remove. After a while they become saturated in calcium, paper dust, ink and hickeys and you'll have to do something to remove them. It should become part of your maintenance regime to 'service' the roller system once a month or so. Poropaste (from Ultrachem) is good at removing ink pigments but doesn't do much for the other stuff. You will have to use de-calcifyer and roller shampoo to get rid of the unwanted waste. Follow the instructions on the bottle. Hickeys have to be removed by hand but only collect on the rilsan rollers so you only have to remove a couple to clean them off. This is all preventative maintenance and will save you time and trouble if you do it regularly. Eventually the build up will prevent the even flow of ink on the rollers and you'll have problems printing.

Check that the roller pressures are still accurate regularly, stop the press and rotate the cylinder so that the plate clamp is towards the delivery end of the press. Now drop the form rollers onto the plate and leave them there for a few seconds. Release them and rotate the plate around to reveal the bead-lines-to-the-plate. If they are all good then all of the pressures are good. It's best to do this about once a month or so, to give warning that some adjustment may be needed in the future.