Comments on: I, too, am having roller problems on my SP-15

By: Jenni Won

Jenni Won — Wed, 30 Apr 2008 05:20:29 +0000

Thanks to Sara who also gave me a very simple and straightforward fix - that WORKED! Yay!

Indeed, my form roller gear wheel had come very loose - so loose that it wasn’t doing much at all really.

I’m still having problems with my inking my entire bed but I’ll tackle that another day since I rarely take advantage of the full bed.

Thanks to all for their invaluable input. I still plan on getting new rollers but it’s not so urgent.

By: Fritz Klinke

Fritz Klinke — Tue, 29 Apr 2008 22:58:42 +0000

Shrink or swell within the expected life of the roller, and using the right solvents. Typically that is expressed in the manufacturer’s one year warranty against defects. Our main reference is that synthetic rubber rollers do not behave like composition, shrinking and swelling with heat and humidity–thus much more predictable in performance.

By: Jenni Won

Jenni Won — Tue, 29 Apr 2008 19:21:25 +0000

Ah ha!

I will try this and hopefully this will fix things in the interim.

I will let y’all know how it goes.

Thanks!!

By: Sara Langworthy

Sara Langworthy — Tue, 29 Apr 2008 19:11:36 +0000

Setting aside that the simplest explanation is often the best (rollers are outta whack): we had a similar problem with one of the SP-20’s at the University of Iowa. The set screw on the form roller gear wheel had come loose and was not making contact with the roller core–it was inconsistent, but would keep the roller from turning smoothly across the form. The resultant crappy inking looked pretty similar to yours, an inked area followed by a skid.
Tightening the screw helped for a while; we eventually used a slightly longer screw and the gear stayed put.

And when we had the money we replaced the ancient rollers.

Sara

By: Jenni Won

Jenni Won — Tue, 29 Apr 2008 18:54:31 +0000

Hi Fritz!

Thanks for your input.

On the NA Graphics site, it says that your rollers are “are made from a soft compound that will not shrink or swell.” Is that true for the lifetime of these rollers or should I still replace them after 2 years?

I will doublecheck diameter although I’m not sure if I will be able to check durometer.

Thanks!

By: Fritz Klinke

Fritz Klinke — Tue, 29 Apr 2008 18:36:00 +0000

Five years is well past the break point for good work–many printers recover their rollers within the first 2 years. I think all the indicators point to the rollers, and as Paul mentions, both durometer and diameter should be checked. If the rollers are less than 2.500″ in diameter, then they have shrunken and most likely not uniformly, so that’s where the problem is. Cleaning all the parts described is fine but doesn’t relate to the inking problem. Correct diameter of the rollers to work with the oscillating and rider roller is important, and the original tac and softness of the rollers, measured in part by durometer, is required for proper transfer of ink. Also check the front rider roller bearings (in each end of the steel roller are bronze bearings) and these should both be the same diameter–if not, get new ones from us and eliminate that possibility.

By: Jenni Won

Jenni Won — Tue, 29 Apr 2008 17:28:24 +0000

Well, it’s inconsistent. There are details I accidentally left out…

I started with rubber based ink and suspected that it was the culprit for the misprinting (it was also printing a little goopy) so I switched to oil based ink. Things seemed to be going smoothly but about 50 impressions later, I was back to square one.

My rollers are about 5 years old. But they seem to be in okay shape. What is the best way to ascertain if it is a problem with swelling/shrinking and durometer?

The ink is just reflex blue - no transparent white. I didn’t put on a heavy coat but I didn’t consider the viscosity.

I’ve tried double-inking but the rollers still won’t hit the tailend of the bed.

By: Paul Moxon, Moderator

Paul Moxon, Moderator — Tue, 29 Apr 2008 15:13:26 +0000

You say the rollers suddenly crapped out, but perhaps you’ve just reached a tipping point. You did not state how old your rollers are. The diameter of one core may be shrunken (undersized) and the other swelled (oversized). The durometer or hardness of the rubber increases over time and is also influenced by other factors (solvent, oxidized ink, light

Also it looks as if the viscosity of your ink is too thin. Is there a lot of transparence white in this color? You could add magnesium carbonate to the ink on your mixing plate.

The second image appears to be a fairly large form. You probably need to double ink it in trip mode before making impression.