Heidelberg Cylinder Base Idea


I posted a topic a few months ago when my company was considering buying a Heidelberg Cylinder SBG (http://www.briarpress.org/62198#comment-81876) and everyone was extremely helpful here, so now that we’ve pulled the trigger and bought that beauty, I had an idea about a couple of things, but thought it might be best to ask here, maybe it’s just a stupid idea.

So we bought this machine because we have one client that is interested in printing books, as well as some other clients (illustrators mostly) that want to make large graphic posters and others that would like to do specialised business cards. Considering that we have that much potential interest, we pulled the trigger.

We’ll do all printing with photopolymer plates with thickness of 0,95 mm, which means we need a base that is 2,61 mm thick to reach that holy number of 2,56 mm for printing. Since the size of the machine allows for quite a large format, I believe we might print 8 pages of a book per side at once (or is this perhaps too much if a single page is slightly larger than A5 format? Especially when it comes to folding later on?), as well as doing large graphic posters. But the frame of the machine is quite restricting if we want to do it all, so I had this crazy idea: why not make the base the size of the frame, with all the necessary holes for fixing it inside the machine. Sure, it will be expensive, but if we’re working with only that one specific polymer, it might be worth it as we only need to use adhesive to get it into place (we would anodise a grid onto it as well so we can position it properly).

Furthermore, after reading so much about registration pins here, I was thinking of adding several positions for those as well. I.e. one for large sheets of polymer and other for smaller sheets, like if we wanted to pin down individual pages of a book to save on photopolymer waste.

Is this idea worthwhile or am I missing something and I should just stick to using a frame like everyone else? Maybe create two smaller bases that I can mix and match as needed?

Hopefully someone can shed some light on this. Thanks!

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John Sullivan at Logos Graphics has used a one-piece chase & base on his Heidelberg KS cylinder. If I remember correctly, it is nearly full bed width, with head and tail conforming to normal chase form.
Personally, I use multiple sizes of base within a standard chase on my KS, and have the head and tail bars for that wider image area. But the thing to consider, and pins will help a lot here, is that you want the plates mounted dead straight. It is not good to adjust the head stops to compensate for a skewed plate if you are doing tight register work, especially on larger S-series presses.

Okay, good to hear that my idea is not that crazy.

My biggest problem from using the frame comes from height actually. Making a one-piece frame & base would allow me to go for a larger page format while neatly fitting eight pages per side, which would maximise the use of the machine and make the printing of the book faster, or at least that’s was the idea.

I only wanted to ask what did you mean when you said you I should want the plates mounted dead straight? I must admit I didn’t quite get that last part.

Laying down a flexible plate with an adhesive back gets more difficult the bigger it gets. Being off at the head will swing your plate out at the rear side. Even if you develop a pin-mount method, it is only as accurate as your ability to place the hole exactly where the image needs it. You can have a plate with pin-mount that still ends up skewed on the base. And in that case, you do not want to compensate by making image adjustments using the headstops (front lays in Heidelberguese) on the feed board of the press. Backing up a book form with similarly skewed plate can be a headache.
With a base within a chase, paper shims can solve a skew problem easily.

Ah, I see, thank you, that was very informative!

One other thing, do you maybe have an example of a good pin to use? I’m having troubles figuring out how would a pin look like since the photopolymer plate is so thin (0,95mm). We found a manufacturer who said they can make anything we want, including the pins and the appropriate holes if we provide him with the exact positions, but I’m having a hard time figuring out what would be the best ones and google is not providing a lot of information.

Thank you!

I use standard 1/4” pins for photomechanical work, but in the chase I am using 16 gauge brads (1/16”) driven into 18º high-base slug, the same height as my PatMag bases. Grind off the brad head until it is just over plate-backing thickness. The holes are made manually with a 1/16” drill in a pin vise, and for register work that position is located by circles in the original document. Even if not register work, the pins prevent plate creep of non-adhesive steel-back plates on magnetic bases.
If you want fabricated pinbars and punches, you’ll need to ponder that process.

Great, thank you very much for the detail explanation!