Every platen or lever press has wear on the rails and needs tape on the rails to raise the rollers to the right height. This is whether you use lead type or polymer—although the problem surfaces more frequently on polymer if the roller rails aren’t set correctly. You have to build up the rails that the roller trucks travel on so that the rollers just graze the surface of the form. The best way to do this is to add equal layers of masking or strapping tape to each rail. Keep building up the rails in this fashion until whatever you’re printing doesn’t ink up at all (i.e. bring the rollers up just past the point where the rollers ink the plate). Then take off one layer of tape so that the rollers drop down with minimum contact to the plate. This will keep ink from getting on the backing of the plate and the base, and it will also help make your printing crisper. It’s not uncommon to have to add as much as a 1/16″—or sometimes 1/8″—in tape in order to get the rails to the right height. These presses are often 100 years old and have 100 years of wear that you have to overcome. We do not recommend that you adjust your trucks or printing plate/base for this problem. Better printing results from type-high rollers. After you add tape to your rails, we recommend using a roller gauge to perfect the height of your rollers.
Posted in: Boxcar Base manual, Letterpress Manual, Printing with a Platen Press