Uneven inking with photopolymer - where to find new trucks/roller bearers?
I’ve already read the many threads on this topic, which made me feel better that I wasn’t the only one with this problem but now it has left me feeling horrible that there is no clear solution. All that’s left for me to try are new trucks and roller bearers, but I cannot seem to locate Delrin trucks for my Golding Pearl Improved No. 11 press. Do they even make them? And I haven’t found anywhere that sells roller bearers, it looks like you have to craft your own?
I currently have the metal trucks that came with the press, and brand new composition rollers. I have no issues printing lead type, only photopolymer. I set my rollers to type high with my roller gauge and some tape, and my typeset pieces printed beautifully. I went to use my Boxcar Base for the first time and had horrible results. I spent all day today working on it again and finally got the perfect print only to lose it after about 10 prints, then it under-inks or over-inks. I know the plate is capable of making a perfect print, I saw it! So it must be traveling ink on the rollers? I don’t see how this issue wouldn’t arise using lead-type as well though? Logically I don’t see how the rollers or trucks could be the issue if they work fine for lead type, but I suppose anything is possible with letterpress printing. Is there something about the lead (or magnesium plates) that would be more forgiving with the ink traveling issue than the photopolymer is?
Hi, kathleencorr—
A couple of ideas you might try. Composition rollers are sometimes not quite round. This can reveal itself during the print run by a sort of “weaving” in and out of adequate inking. Ten or fifteen impressions will be fine, and then the rollers will have worked around towards their undersized side and the next half-dozen impressions will be underinked. Then the inking will seem good again for a bit, and so on. The solution is to set the rollers (if possible) to their lowest spot, that is, so that they print well from the low spots, and perhaps overink on the high side. More form rollers help too.
Another test is to place a piece of bond paper (about .003”) under the base, to see if that brings the plate up to touch the roller. With an eight or ten power loupe, you can examine the sides (“neck” or “beard”) of the type to see if ink shows there, which would mean that the plate is getting inked and the problem is elsewhere.
When you pull a stripe on your typehigh gauge to set the rollers, take a stripe from several spots on the roller by turning it with your hands. That should tell you if one side of the roller is lower than the other. I like a stripe about a pica wide, but some light forms will take less if your rollers are truly round, centered on their cores, and parallel.
Try these ideas first, before spending any money!
Regards, Brian
Have you checked to be sure you have the correct height base with the plate? Photopolymer is available in different thicknesses, and if yours is a bit thinner than the base is designed for, that could be the problem too. If you have a type-high gauge you can check the height-to-paper of the plate when it is mounted on the base.
Thanks for the comments!
Brian - I do think the issue has to do with my rollers or trucks. I store my rollers suspended in a protective box to keep them round but I didn’t know that it may be their very nature to be imperfect. Your idea to use the gauge and move the roller around is a good one! I will give that a try when I can work on the press again.
AdLibPress - I have the deep relief base and matching plates. I don’t seem to be having an issue with impression at all, since that is a separate variable from the inking issue. I practiced printing without ink first to make sure the impression was even.
Kathleen,
I’m not familiar with the “Golden Pearl” presses. It sounds like they operate similar to Windmills as far as rollers/trucks are concerned.
It could be the rollers although if it prints fine on lead type or mag then it would be fine on polymer. When I get ghosting where the print floats in and out the solution is to bring the rollers in tighter. Obviously you don’t want them to tight or the print looks like crap. I have found that when switching back and forth between lead/mag or Polymer I do have to adjust the rollers slightly even if the type height is supposed to be the same.
Maybe post a pic of your rollers and trucks? Also if you cannot find new Delrin trucks let me know. If you have the specs of can send me one I can try to make you new ones on my lathe.
Good luck
Ronnie
Kathleen
You’ve read all the threads so the only thing I might be able to add is that metal type and photopolymer plates do not use the same roller settings. You mention you set the rollers at type height? Not sure what that means. The rollers need to be lower than that.
Photopolymer plates don’t need a heavy strike. On a Vandercook or Heidelberg in really fine condition, I’d say 1/32 plus of an inch of ink strike. Type was usually specked at 1/16 plus of an inch. At any rate, not the same setting. Not sure if that will help.
Gerald
http://BielerPress.blogspot.com
I’m having the exact same problem!
Gerald, according to 1/32 strike for polymer / 1/16 strike for type, the rollers would need to be lower (closer to the bed of press) for metal type and higher (farther from bed) for polymer. If Kathleen and I are both getting good results with type, that means our rollers are in a lower position, which should be over inking the polymer — but the exact opposite is happening, under inking. What am I missing?
akluna
You might want to take an impression strike (without ink) of the type form and the photopolymer plate/base. While bases like the Boxcar and Bunting are noted for their precision, there are certain tolerances stated by the manufacturers. In other words, are the bases with mounted plate actually type-high? If not, you would need to underlay to make them so.
Gerald
http://BielerPress.blogspot.com
I set my rollers using a roller setting gauge which is .918” in diameter. When I get a 1/16” stripe on the gauge, I consider myself well set. Using rubber rollers which have been ground concentric to the roller shafts, this setting works for both photopolymer and typeset forms. It seems to me that there should not be a different setting for typeforms and plate images if they both are the same height.
I have, however had problems with molded rollers being not concentric with the shaft. This can be a very big problem if the rollers are off by as much as the depth of the relief of the plate, and I have seen composition rollers off by that much.