Monthly Archives: May 2011

Ink Rollers

After considerable back and forth I am back to where I started. When I got the press there were only two of the three ink rollers present. Since I am going to use the press to print from engravings rather than from movable type (individually placed lead letter forms), the inking procedure is maybe a bit more critical. The rollers are built on a steel core of 9/16″ diameter, with the center 20″ covered with rubber to a two inch diameter. The roller trucks are slightly smaller in diameter, the idea being that the rollers are moved along by the trucks rolling on the rail until the part of the form that needs to be coated with ink is contacted by the rubber roller and sightly lifted, with the roller now rolling along the surface of the engraving (inking it).

Due to a chance encounter with a structural engineer in a coffee shop I got an education in the deflection/deformation experienced by the rollers as they move over the form (the parts of the engraving that gets coated with ink). Dave is his name, and after I asked about the workability of higher quality steel versus the original mild steel rods, he told me that I was addressing the wrong valiable. With a solid rod the strength of the steel has only a minor effect on deflection. He then explained the equations behind the resistance to deflection in a rod versus a tube, that is where the improvement can be had – making the portion under the rubber a tube would make it a lot more rigid.

Great, now I had a mission. I determined that a one inch OD tube would be ideal, would result in a half inch coating of rubber to get to the original two inch roller OD. Now I just had to figure out a way to insert the 9/16″ rods in both ends of the 20″ long tube and then everything in the roller saddle areas would be back to the original version. My approach to this is to get the tube line drilled at the ends, for say 3″ and to – with a slight interference fit – hammer in the shaft stubs for each end. About one inch from the end of the tube a 1/8″ hole can then be drilled perpendicular through the tube and shaft, and a spring pin hammered in to hold things together. Another set of spring pins can be used to hold the delrin trucks in place, and since they are made to specifications I can get them made the same diameter as the roller OD.

And then I had the great epiphany, what if the original roller cores were made of such small diameter steel in case the rollers came off the saddles during printing? I have heard of that happening. That would be a mess, if the rollers fell between bed and platen while the press was closing! So now I have another mission – is that a valid concern? Onward…

Leave a comment

Filed under C & P, C&P, Letterpress