Cylinder Undercut Variables

[In a previous post I stated that all 4Ts have an cylinder undercut of .070″. —PM]

Just to add my two cents, my 4T cylinder is undercut to .070″ as are the other 4T’s at the Wells Book Arts Center. … I’m curious why a Uni I manual at the Center would have been undercut to .160″? That’s got to be some sort of record depth, but controling that much packing (near 8 sheets of .020″ hard packing) is a headache. —Terry Chouinard

8 thoughts on “Cylinder Undercut Variables

  1. Fritz Klinke - October 4, 2006

    I had a little help on the SN from Paul earlier in the day—he tracks such things from all his teaching visits to schools and service calls.

    The device you mention was probably used in testing printing characteristics of paper for such things as picking, tearing, etc., under simulated offset printing conditions using stress gauges tied into a computer. I’ve seen such a setup at the International Paper Co. labs outside Cincinnati, and Nancy Plowman Associates, provides test equipment and converted Vandercooks to paper mills for this purpose. A number of Vandercooks are still in use for quality control purposes in paper production. Coming from a printing school, I’m assuming that this press was used in the same manner.

    We’ll provide more than a cot and also meals for any indexing volunteers that stray out this way. Summer is best unless you’re into snow sports and the cold of winter. We do have heat, plus there’s a fully loaded letterpress shop to play in as well as all the Vandercook material.

  2. Eric Holub - October 3, 2006

    Another way to fill up such a deep undercut is to use a rubber underblanket. I use a .030″ blanket (from Fritz) on my .070″ undercut 325G, with hard packing above it. A more typical offset blanket is .065″. Maybe add a few .010″ litho plates to that, and you have made up much of the difference from standard.

  3. Fritz Klinke - October 3, 2006

    Alas, Terry’s press, SN 29621, does not have a card on file, only a note I wrote in October of 1997 that this press was at RIT. But it dates from 1973 and is at the almost end of Vandercook production. Many presses went to uses other than for printing–paint companies, flooring companies like Armstrong, cork fabricating plants where these were used as short run diecutters, etc. So, a cylinder with this extreme an undercut was for a specific purpose we may never know at this point. Even Kodak in Rochester had a number of Vandercooks, including some with special features, so this could be one of those presses.

    We do have some .010 Cromwell tympan on hand that might work for the Univ I–I’ll have to check. Another possibility would be to use Engraver’s Board, and that’s around .030 thick, but is not of a uniform caliper. A top sheet of mylar may stand up to the tearing problem, and is a common top sheet anyway–strong, but flexible, but the shingling effect also limits the start of the image area. Paul’s idea of binding the leading edge together has serious merit to it.

    I can use all the help I can get here in Silverton, and a good start would be to cross index all the Vandercook drawings—what an aid that would be. I hate to spend an hour or two tracking down the size of a dowel pin, as an example.

    A question that occurred to me is the position of the gripper bar–is it even with the surface of the unpacked cylinder, or is it raised to compensate for packing?

  4. Terry Chouinard - October 3, 2006

    Thanks Fritz. Where did the s/n come from? I’ll check on the press itself tomorrow. If it is indeed SN 29621, I am going to be thoroughly impressed. And a little freaked out too. How can someone channel serial numbers across three time zones? I know for sure it is of the ITW vintage, the carriage proudly says as much.

    To answer your question, the gripper bar is raised to compensate for packing. I should send you an image of the two holes someone at RIT drilled in the bed of the press as well. Seems there was some sort of primitive digital attached under the plate at the end of the press and it was connected to a triggering device srewed into the bed of the press. Don’t ask me, I just spend 30 minutes taking it all off when the press arrived and stowing that stuff in the nearest dumpster.

    I would be happy to volunteer some time helping index the archive material, but I’d have to talk with the Mrs & the accountant first. I know all I’d need is a cot and directions to some decent eats and a key to the water closet.

  5. Terry Chouinard - October 3, 2006

    Thanks Paul. I know attaching the packing at one end is a technique Harold at Boxcar employs. I wonder if the Kimlon is more flexible/pliable than the .020″ pressboard. If so, I wonder if multiple Kimlon blankets might help even more. I hadn’t even considered a .010″ topsheet. Brilliant! I have a stash for our 325G. I’ll cut one down to fit the Uni 1 and see if it helps.

  6. Paul Moxon, Moderator - October 3, 2006

    Perhaps glueing one end of the packing sheets to one another may prevent them from slipping away from the gripper bar and beveling. It sounds like a bother, but if it works just call it makeready. You could also swap one sheet or more of the .020″ pressboard for a .021″ Kimlon blanket and place it on the bottom next to the cylinder.

    For a stronger drawsheet consider .010″ tympan instead of the standard .006″. A 10 mil mylar may also be serviceable.

  7. Terry Chouinard - October 3, 2006

    Thanks Eric. This press is on permanent loan to us from Herb Johnson. He acquired during his tenure at RIT, although I don’t believe it was a press in Lawson or Provan’s classes. I knew I could send Fritz the serial number. In fact, I think I did some time ago, but it may have been a daunting email. I was bothering him for the manufacturing histories of all 8 of our Vandercooks. I’ll have to write him again, perhaps this time with an offer to volunteer time in CO entering such card information into a database or spreadsheet.

    The most difficult problem dealing with such a deep cylinder is controlling the packing as it curves around the cylinder. I’ve been using .020″ blue pressboard (from Xpedx) to fill most of it. Works well so long as the grain direction of the board runs across the cylinder and not around. Still, the curve creates a bevel at the beginning and end of the packing. That small bit of angle creates a gap between the grippers and the beginning of the printing surface of the cylinder. Also, so much packing requires me to use two topsheets, otherwise the tension of the packing will make a tiny topsheet tear into a big one very quickly.

  8. Eric Holub - October 3, 2006

    If you give Fritz the serial number, he can look up the original purchaser and any special circumstances of manufacture. And a .160″ undercut would seem to be a special circumstance!
    –Eric Holub. SF

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