Printable View
Heidelberg letterpress in operation.
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Previously:
https://www.homemadetools.net/forum/...335#post158110
https://www.homemadetools.net/forum/...580#post166820
https://www.homemadetools.net/forum/...711#post128888
In case anyone is wondering, "Why is the press feeding sheets through that are already printed?"
This press is being used in a secondary operation; likely for sheets of a limited run printed on an offset printing press.
(Large operations usually have systems that accomplish all operations on one machine.)
Ths press is setup with either, slitting rule, perforation rule, scoring rule or combination of these.
The ink tray and inking cylinders have been removed and replaced with clear cover guards.
When you look at the bed of the press, you see reddish strips. Those are rubber foam surrounding what die rule is set into a plywood sheet.
This 'Die matrix' (die locked into the 'chase' metal frame locked in place with quoin locks that exerts pressure sideways from the sides.)
The whole unit is laid onto the press bed and the side locks are tightened to keep it from moving.
If the printed sheet being worked is .010" thick, the impression is set for that plus another .0010" to .0015" deep.
The cylinder, has a steel jacket clamped on to it with silicone strips that match the die rule being used to take the cutting edge.
This provides a 'Kiss cut' that is just enough, but not too much to accomplish the work.
Many of these Heidelberg cylinder presses were converted beginning in the 60's and 70's to do die work.
Other secondary operations include numbering and hole punching.
Many printing operations are still in a similar situation to machine shops.
How much time does it take to program a CNC to do this whole job?
versus
How long would it take to do it on 3 different machines?
In medium and short run jobs the old equipment is still more economical to get a job together at times.
It's hard to tell but the die board doesn't look to be cutting anything as the corking would run on both sides of the cutting rule, likely just a scoring operation but still love to see these older 'bergs working away! Ours is a nonstop, 7 print stand, web-fed flexo press with front and backside print / coat capabilities and a sheeter at the end. We can go from 6' diameter paper rolls to printed, coated, sheeted stock in one operation. We had the option of an inline diecutter but the machine is already 170' long and we would have had to remove a wall to add it! It could literally run non-stop until we ran out of paper, which we did when many of the mills closed due to covid! Supply is a mess and probably will be for another year or so...
HS
For me, it is hard to tell because of the minimal time showing the die.
We don't always have rubber right up on strips; it depends on the effect on the sheet.
The NOS could be but again it's not long enough or close enough for me.
There are jobs, for various reasons, that may be scored before being sent to a folder.
(for instance: a booklet cover where there is a very distinct line that is going to be very apparent if it isn't folded exact.)
The most likely, the stock doesn't fold exactly because of the stiffness of the stock (or contrary grain in the sheet)
OR
The stock has a top coating that makes it susceptible to scratching and the pieces will actually be folded by hand.
It is a fact paper supply is all over the place for many reasons and not all of them are good reasons.