I recently attempted to print a very light color of borders that extended from the top of the bed about 10 inches. The ink was mostly composed of white and revealed things about the press that are perplexing. I have several issues going on, and perhaps this was, unwittingly, a test of all of them.
For one thing, I have not got anywhere on the previous post, because I made committments to being ready for shows and having prints to sell at them. I worked around my issues. The roller bearing adjustment has not been done yet. See this post:
I have issues with the top of the bed consistently not having the same amount of impression. During this printing, I can see that there is an abrupt change in color. The top of the bed color looks good, but then it is very muddy. We discovered a feeling of wear on the bearing rails that dips slightly, felt by running a finger over the metal. It is right across from this that the change in color/impression is muddy and heavier. If the bearing rails are worn, then maybe some paper or tape might fill it in. I tried a little, nothing happened. I had to stop my experiment there for the day.
It is also possible that I have set my rollers too low, even with what appears to be the right ink strip size. That is the only thing that comes to mind that might cause the muddy color. Then the form rollers are pressing on the type or sliding (though this is hard to actually see) and dragging/pulling with it issue No. 3. I can’t get my rollers clean. I think I need new rollers. Even after having light ink on them, if I really scrub form rollers with type wash I can always get more dark ink off. Or are the rollers degrading? The roller next to the motorized roller is pitted toward the ends and traps ink all the time.
I know, I sound like a basketcase. If anyone would like to suggest a direction to pursue first, I would be grateful. At least I have no imminent printing plans and I would like to solve these issues if I can.
Do you have this form securely locked up to pica measure, or are the border components just sandwiched between pieces of furniture and locked in with a quoin? Some of this is clearly off it’s feet and this will cause some of these issues as areas of the print surface rise above and drop below type high. It might be shifting because it is not properly locked up on the press.
I would also suggest making sure that you have the correct amount of hard packing on the cylinder to correspond to the paper you are using. Also be sure that the tympan is set properly centered and tight.
If you can afford to put new rollers on your press you will absolutely not regret it. Be sure that when you send them out you remove all hardware including the tiny woodruff key that keeps the gear in proper alignment.
DGM
Thanks everyone for all the suggestions. And KPMartin, I knocked the type down several times during printing, but so far I have not moved it down the bed to test that theory. But I could very well had some border being pushed up.
This form is all metal.
I do have some new info today.
I’m pretty sure we can rule out the adjustable bed being off from the rails. We took a level, the best one we have, and just got a slightly higher top of the bed reading which was consistent from bed to rails. The press may be sitting just a little high on that end. (it’s on 4x4s)This does not seem consistent at all with my impression problem, so it seems unlikely that this could cause it.
We measured the diameter of all rollers with a digital micrometer. The form rollers that are supposed to be 3.0 inches are: front roller: near end 2.9085, and 2.88 the rest of it. That seems significant. back roller: near end 2.9135, middle 2.8975, far end 2.9045.
The (adductor)roller that contacts the motorized drum is 2.8975 all except near end 2.964.
Large steel roller: 3.821, 3.819, 3.8195.
I could not feel a low spot on the rails today! I took pics of this as well and noted that no grooves are there. However, it seems the cylinder carriage bearings would be the place to start, since the adjustable bed seemed ok. Using carbon paper to check impression. And new rollers.
Some of this looks like tilted type. In the wider border (closest to the bottom of the sample), the 7th and 10th units look like they have tipped to the right, giving them gradation from dark (on the left) to light (on the right). There seems to be extra space between the units there which would also indicate tipping.
The dark shadow on the left edge of each of these types might be some combination of too much ink, too-soft ink, forme rollers too low, too-hard rollers, and/or roller skidding, any combination of which will tend to ink the beard of the type.
If you want to distinguish cylinder/bed problems from type problems, move your forme lengthwise on the bed and see if the printing flaw moves with the type or is always the same place on the bed. If the forme is loose (rather than locked in a chase) moving it on the bed might randomly alter problems like tilted type. If the problem remains at the same place on the bed, there are still many possibilities include bed/rail-related inking problems.
Problems with the forme rollers would repeat at the circumference of the rollers (about 9 3/8″ in this case), but would move from one impression to the next as the rollers start in a new position each time.
Another way to distinguish any inking problems from any impression problems (other than John Henry’s carbon paper method) is to ink your form by hand with a brayer.
Like press troubleshooting, packing everything into one comment can be overwhelming. Tearing down and cleaning an adjustable bed can seem daunting. I’ve done it several times now.
Remove the sheet metal panel end plate, as well as the head dead bar and foot dead bar or lockup bar. Inspect threads of the shaft and gear(s) for debris and lubrication.
The top taper sits in the bed and can be lifted out by turning hand wheel until it overhangs to the right of the bottom taper, allowing a pry bar. Rock the top taper back and forth by hand to loosen. Insert lengths of wood underneath to support it and aid in removal. Note that the bed taper is very heavy. In most cases the bottom taper can be cleaned in place without disassembly, but make sure to also clean the side walls of the bed housing and the areas front and back along where it slides. Tapers on the 15-21 and Universal I closely fit the bed housing, while the 219 and Universal III have strips of felt to fill gaps along the length and right end of the bed (replacement felts are available from NA Graphics). To lubricate the tapers, the manuals recommend Molykote Z, but this is expensive and not commonly found. Instead use a heavy-duty clear penetrating grease, such as ZEP 2000.
To calibrate bed height, place type high material in the bed, and adjust hand wheel to make level with the bed bearers. The indicator wire should read 0.918”. If not, the scale can be adjusted. For photos of an adjustable bed tear-down, see flickr.com/photos/its_fancy_letterpress_studio/sets/.
It would appear that the impression adjustment might be the first to tackle as even inking will not overcome poorly adjusted impression. The fact that the press has an adjustable bed throws one more variable into the mix. It may not be totally cylinder-to-bed problems, but rather something causing the bed height adjustment to be out of kilter. I have had one of these apart (long ago) and remember it being a very simple (although heavy) mechanism.
If you can get hold of a very good machinist’s level, you could take readings along the length of the cylinder bearers and compare with the readings of the bed at adjacent points and see if they diverge. If all looks level, perhaps that will eliminate the factor of the bed mis-adjustment, and you can move on to the cylinder.
If you can use carbon paper rather than depending on the inking system, that will eliminate any false results from inking adjustment and give you just the effect of impression on what you are doing. Back off the bed so that you are just beginning to get an impression, and you will see what is happening in a different focus.
As Paul has said, a press with multiple problems requires troubleshooting one problem at a time, even though as a printer, you’d like to get rid of all at once.
John Henry
All troubleshooting must start with examining each element separately. For every one that’s out of spec the problems become exponential. As each one is standardized it can be eliminated as a cause.
Low spots on the under rails are a major obstacle to overcome. You can place metallic tape, but this will require much trial and error. And expect to replace it frequently.
Later Universals (and SPs) have bolted on rails that can be replaced. Planing isn’t really an option, but the metal is surface-hardened and softer underneath. Better to replace the rails. This is expensive but far less than a new press (if you can find one with good under rails).
Futhermore:
Roller diameter should be close to 3.0″. Less important is durometer, or hardness, which should be to 20 (up to 30) on the Shore A scale.
For dark to light color changes use a deep-cleaning roller conditioner such as Van Son Easy Street.
You don’t say what kind of plate you’re using. Is this composed lead type ornaments or photopolymer? The latter is less forgiving when rollers are out of spec. The roller setting gauge is also susceptible to wear. A visible flat spot is indication that it is less that 0.918″ high.
Plate base dimension should be uniform. A base made of medium density fiber board (MDF)could have as much as 0.005″ difference from side-to-side. That’s nearly the thickness of tympan (0.006″).Even when a Boxcar base is used grime underneath could affect the height to paper.
Lastly packing should be uniform and fresh.