I’m somewhat new to using a letterpress for printing. I recently bought a Kelsey Excelsior 6x10 that was in pretty good condition. The only major thing I had to do was replace the rollers.
Overall, it works pretty good, but I’m having a few reoccuring issues when printing.
First, im getting a harsh, heavy line of ink around the edge of the print in most cases. Typically on bottom part of the plate (the part of the plate that is closest to the rollers when locked up in the chase (see attached photo). Any idea what could be causing this and how to remedy it?
Also, I’m having trouble getting good ink coverage at times on the plate. It’s seems to be happening in the same section of the plate each time. It helps if I double or triple ink before printing. It will also help if I add a bit of manual pressure to the rollers as the glide across the plate. The weird thing is, it seems like the rollers are making decent contact with the plate without me doing that. I’ve tried everything… more packing, less packing, more ink, less ink, adjusting the platen, adjusting the tension on the rollers, etc.
I know it’s probably hard to give advice without seeing this in action, but please let me know if you have any advice!
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It appears that the rollers are hitting the edge of the image and at that point are wiping off the very edge of the ink, leaving it on the outside edge of the image. You might try adding a strip of image plate material at the edge of the base at a point where the rollers will hit it prior to hitting your image. This will start the rollers turning at the proper rate before they hit the image areas. If you can do this outside the paper area, it will not print, and will possibly alleviate the problem. It will deposit ink on your tympan paper, and you might need to clean it off every 20 or so impressions.
Generally I have seen this when the trucks are not keyed to the roller shafts, so that it is hitting the image that starts the rollers turning. If this is not the case, you might have to reset your rollers so they are just a tad higher.
Roller diameter, roller truck diameter, and rail height are all pretty critical for printing with photopolymer, if that is what you are doing. The rollers should just kiss the raised image, so if they are “hopping up” onto the plate that is part of the trouble. But John may have nailed it — ink roller bearers outside the area of the paper will often cure both roller/truck diameter issues and low rails, all of which occur often on the small tabletop presses.