Old problem, new solution (maybe)
This may not be a totally new solution, but, I am not aware of anybody trying this.
The problem: How to adjust the height of the rails to fix an inking issue. The common solution is tape. It’s not a great solution, but, we don’t seem to have any good ones short of having a machinist do some expensive fix. I don’t think the machinist fix is very practical for most people. Notice I didn’t talk about taping trucks. If your rails are worn, taping trucks is not appropriate. It is not addressing the problem correctly.
I had just finished the restoration of my Merritt Gally Universal and was dialing it in when it became clear the rails were worn on yet another press I had restored. I did not want to go to the tape fix. I wanted something better, but, short of the machinist work. I think this is a worthy solution. Maybe it will be a doable fix for others, so I am sharing my experience.
The solution: I purchased steel shim stock from McMaster Carr. https://www.mcmaster.com/9300K14 In my case I used the .008” sheet and cut it(ordinary paper cutter) into two pieces the width of the rails on the press. I used 3m spray adhesive and sprayed the back of the shim stock then immediately applied them to the rails. I purchased metal ducting tape to seal the very ends of the shim stock for added security. I gotta tell you it works great. It is much more accurate than tape and does not dent if the trucks are left on the rails. It has only been on a month, but, there are no signs of failure. If it does, I can clean the old adhesive off with a solvent and reapply the glue. It looks good too.
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I like that as a direction. You’re right, taping trucks is usually not the way to remedy it. I think a lot of presses were just originally made with rails too low to begin with.
John, this is a good idea but a baseline if you have varying forms.
Look, when these presses were made, .918” was not a US or global industry standard. Every foundry might have a different type-height, so pressmen dealt with variations as normal. Underlays, interlays, overlays were all part of a journeyman’s skill-set; track and truck adjustment too. Today the use of photopolymer plates (and #@&! transparent PMS inks) requires far more precise adjustments than the metal forms and opaque inks of our ancestors.
My take: First, rollers and trucks must be about equal, or there will be slur. The old idea that trucks should be 1/16” smaller than rollers comes from soft composition rollers needing to contact varying heights of worn handset type; this is not the contemporary practice of Briarpress printers.
When I started using photopolymer on a C&P, I had adjustable Morgan trucks and composition rollers, the worst possible combination. My real education came from the simple observation of the ghost image of a 1” circle on the roller and comparing it to the actual form, and seeing distortion. If the circle isn’t exactly the same on the roller as the form, you have slur and need to adjust truck to roller until there is no slip. Only then can you adjust roller to form for proper contact. And consider that different forms need different contact. A rule form vs. text form vs. display form, they’re different needs for roller contact, and a mixed form, that takes real skill.
My Victoria actually has adjustable tracks, but a faulty mechanism, so I use tape and adjust it for each job depending on form. .005” white drafting tape and .0025” clear tape are adequate for any adjustment for metal or photopolymer forms. I replace continually for results, lighter for photopolymer and heavier for metal; mixed forms are common here, so there may be localized corrections on the tracks.
Eric,
Thanks for your thoughts. I agree with all your points. Especially the truck/roller relationship. I am extremely concerned and careful when ordering new rollers. This press for instance was ordered at 1.993” for the two larger diameter rollers. I’m not sure the roller companies can accomplish that degree of accuracy, but, I ask, and I have returned a couple of orders for regrinding in the 8 years of restorations I’ve done. I am a firm believer in the trucks being the same diameter as the roller. I do realize that the rail height adjustment I made is not going to work for all projects. I set it up to work with most polymer projects. (a nickel thickness stripe on the roller gauge) So, it is set up to have a light pressure on the correct thickness form which satisfies most of my projects. I also have several presses to choose from should the project really not be well suited for this setup.
John