Casting Urethane Rollers for the Kelsey

We’re a makerspace with a letterpress studio, so we’re in the fairly unique position to make stuff rather than buy it, as well as do fun stuff like welding cast iron to repair presses. We were given a couple of the little Kelsey presses for our classes, and they needed rollers.

After trying out some neoprene materials with not great results, we did some research and tried casting our own urethane rollers. Popped them out of the molds this morning, and they look really good. We’re going to let them cure for a week or so, and then try them out.

The blog post with the details is here:

image: Screen Shot 2019-11-10 at 10.29.18 AM.png

Screen Shot 2019-11-10 at 10.29.18 AM.png

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Got the second one cast, and did a test fit while it continues to cure. They still need to be trimmed, but look pretty good:

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They look great! I’ll be interested in getting more feedback when you start printing with them.

A couple of things that come to mind are:

1) were you able to get the rollers close enough to being concentric on the cores (shafts) with your method of taping the trucks? If not, this would probably be easy to fix.

2) over time, will the roller compound come loose from the cores? With old rollers I have seen, there was string or other material wrapped around the cores to help the roller compound adhere to the core under the repeated mechanical forces of printing. If the roller compound did come loose, you could probably wrap some duct tape or other material around the core so that the roller compound could get a better grip.

Finally able to work out some bugs: After a couple of false starts, first from not washing off the mold release enough, we thought, but even then the ink wasn’t really staying on the rollers, we put them in a lathe and ran some 600 grit sandpaper over them to take the shine out. They work great - some fast and dirty tests:

Sorry, I missed your questions Geoffrey. Yes, they were pretty much perfectly centered. I can’t see the need for anything more precise.

Yes, the rollers I cut off had that string wound around the shaft, which I didn’t put on our test. I will next time, it’s already loosening up in spots.

Thanks for the feedback. I’m not surprised you had to take the shine off the rollers. Rollers are not supposed to be shiny, but rather are supposed to have a very slight roughness to hold the ink better. I think pretty much all of the rollers which are made by vulcanizing rubber or other materials on the cores, are ground afterwards. I think the rollers are basically chucked into a lathe and then a tool post grinder goes across the surface to grind them (although the roller companies undoubtedly have dedicated machines for this).

Geoffrey, sorry but your comment is incorrect. When running Heidelberg cylinder presses and large Miehles we would use one smooth polyurathane roller in the roller train inking the type which acted as a scavanging roller and picked up paper dust. They were generally slightly softer than the rubber rollers and were just as good at inking. We also used gelatine compostion rollers but they could not be used on high speed presses as they would overheat and melt. I had one melt on a press, took quite a while to pick the bits out of the type.

Interesting. I left the shine to start off because we have some urethane rollers that are quite shiny and work fine, but these didn’t - it must be something specific to this compound that we used.

I think you’re right about grinding the rollers for precision tolerances, we may try that just for fun at some point. With these rollers I’m not sure if we’d have to freeze them or something, but they’re pretty soft and didn’t really want to get sanded. ;)

Frank, thanks for your comments. To hear you say you did use a smooth polyurethane roller on large presses, that is interesting. Aside from that roller, what were the other ink train rollers on your large presses made of? Regarding composition rollers which I agree are smooth, I didn’t mention them because they are to the best of my knowledge unavailable, unless a few people still make them themselves.

Now talking about a rubber roller, after the rubber roller compound is vulcanized onto the core, it still needs to be ground to size and to make it perfectly round. I think most rollers that people on this site use for letterpress are rubber. Note paragraph 7 of the following article. Even though they are talking about offset rollers, our rollers are basically the same. It is hard to find info specifically for letterpress rollers any more except from people like you who have first hand experience, and for that we are fortunate. I never ran a letterpress larger than a 12X18 C&P and 10X15 windmill, so I don’t have large letterpress experience like you do.

Note especially paragraph 7:

Regards, Geoff

Awesome piece, thanks for posting!

Geoff, glad you found my note useful. I was printing 45 inch sheets on the Miehles and German Rotaman sheet fed rotaries all with rubber rollers as were the Heidelberg cylinder presses. Now I just have a windmill as a hobby press and again still use rubber. My Miehle Vertical was also kitted out with rubber rollers although I did have a couple of polyu rollers but they had gone very hard with age. A bonus with polyu rollers I found was they were eaay to clean and did not adsorb ink like the rubber rollers.

Frank, this reminds me of another thing that used to happen on the small offset presses. Paper lint would get picked off the paper and would work all the way back through the roller train and end up in the ink fountain, especially on jobs where there wasn’t much ink coverage and the same ink was in the press for a long time. I never could figure this out until someone explained it to me. They said the most tacky ink in the press was the ink which was taken out of the can and put in the fountain. As the ink was used up out of the fountain and was worked up by the rollers, and worked its way through the roller train, it would get less and less tacky. Finally when it was printed, it was the least tacky. So what would happen is the ink on the blanket would pull the lint off the paper and onto the blanket. Then since the ink on the plate was just a little more tacky, the lint would be pulled off the blanket and onto the plate. Then since the ink on the form rollers was a little more tacky still, the lint would be pulled off the plate and onto the form rollers. Then since the ink on the ink train rollers was yet a little more tacky, the lint would be pulled onto them. And so on until the lint would be pulled all the way back onto the fountain roller, and then it was pulled into the fountain where the ink was the most tacky.

For this reason, at the end of the run we never took the ink out of the fountain and put it back in the can, because it was full of lint and paper dust.

Did this happen on your big letterpresses too?

Interesting story about lint in the ink on small offset presses (and presumably large ones too). I have run millions of impressions on Multi, A. B. Dick and Hamada presses and never gave much thought to the why but certainly rarely would ever return ink to the can.

Geoff, that did happen, the company I worked for started in 1777 and closed in 2015, in the later years it specialised in paperback production but when I worked there they did a good range of comercial work as well. That said I did a fair amount of novel printing on bulky antique stock which tended to be dusty. We used an ink that dried by absorbtion and came in 56 lb drums and it was not unusual to have that ink in the duct for the whole week, although we washed up the rollers each night we had a way of leaving the ink in the duct without it drying, before the advent of sprays to stop the ink skinning over. This was to was to clean the duct roller a bit at a time and apply lubrication oil to the cleaned section then covering over the ink in the duct with an oiled paper strip. It could be pretty mucky by the end of the week.

Frank and gachap, thanks for your replies. I never get tired of hearing about the experiences of others. My family printing firm started in 1868 and lasted until about 1971. It was started by my great grandfather but by the end, it was run by a cousin of my mother’s. My great grandfather specialized in printing drug labels. I have a book that was published about the history of drug containers and their labels, and in that book my great grandfather’s business was credited with being the first to ever print poison labels in red.

This is fantastic!!!! Gonna try it before the end of the year!!!!! (hopefully!!)