August 06, 2005

McGiver Press, How May I Help You?

WARNING: This post will probably be tedious even for my fellow printing pressmen. (Anybody out there run a printing press?) I'm writing this more for my own amusement than for whatever readership I have left, mheh. Anyhoo...

A few days ago my boss asked me if I could run these #5 1/2 envelopes. They're little brown coin envelopes that measure 5 1/2" by 3 1/8". I grabbed one and put it on the press's register board to see if the side guides and the guide wheel could register it at the elevator frame.


Oh, right. A little nomenclature for the uninitiated is in order. Since most machine parts are named for what they are and/or what they do, this shouldn't be too hard to explain. I hope.

Here is the press that I run:


That's not my actual press, it's a photo I found online. But, it's the exact model -- Multigraphics 1360 -- that I run.

Anyway, at the front end of the press (the far end in the photo) is an elevator that the paper envelope pile sits on while it waits to be fed onto the register board. The height of the pile of envelopes is controlled by an up-and-down bobbing paper height control bar. As the paper is fed into the press the elevator will automatically raise the platform.

There are blowers along the sides to the paper pile that keep the paper fanned for easier grabbing by the suction feet. The suction feet will grab the envelope and feed it to the pull-out wheels which, in turn, feed it onto the register board where it is moved on a conveyer consisting of five 3/4"-wide guide belts. The envelope will be secured against the guide belts by one or more guide wheels and several spring guide strips that simply ride atop the guide belts. (This just keeps the stock from flying loosely all over the place.)

The envelope will be conveyed across the register board until it meets the stop fingers at the elevator frame. (Why is it call called an "elevator frame"? Beats me, but it's a complicated assembly that consists of what I'm going to mention in the next few paragraphs.) The stop fingers are several steel projections that move up and down as the press runs. When the envelope meets them they will be in the up position. The front of the envelope will be at the stop fingers while a guide wheel is just at the back edge, keeping it nice as snug against the stop fingers.

One other feature that needs to be mentioned at this juncture is the trip switch. The trip switch is located just along the same line of doohickies as the stop fingers, and is what tells the press "hey, there's a piece of paper here!". Without the trip switch, the press would need to make an impression every cycle. This would be bad 'cause if there's no paper passing through the image would be printed on the bottom impression cylinder, and the pages that followed would have that image on their back sides.

Anyway, once the envelope is caught between the stop fingers and a hard place, the oscillating left side register guide will move in and jog the envelope up against the stationary right side register spring guide. The envelope is now "registered". It is in position to be fed into the press, and every envelope that follows should be in that exact same position. (When you check your proofs to see if all of the images are in the same position on every sheet of paper, you are checking the "registration".) All of this so far happens in about half a second.

The stop fingers will then drop just as the feed rollers close, grab the envelope and feed it into the impression cylinder's grippers. The grippers are several 1/2"-wide clamps that pull the envelope through as it is then pressed between the impression cylinder and the blanket cylinder. The blanket cylinder is the one that carries the ink.

After the envelope is imprinted, it is fed to one of three gripper bars that rotate on the chain delivery. The chain delivery gripper bar carries the envelope all the way to the back of the press where it is dropped onto the pile of envelopes that took that same journey a moment earlier.


So, as I was saying, my boss asked me if I could run those little #5 1/2 envelopes. I checked to see if the guide wheel could reach forward enough (5 1/2") to hold them up against the stop fingers. It could. Of course, it could. I've run 5 1/2" x 8 1/2" the short way plenty of times.

But, could I set the register guides to have the envelopes meet two of the stop fingers? (The stop fingers are several inches apart.) The 3 1/8"-wide envelopes ju-u-u-u-st made it, but there was little elbow room. I would have to be precise when I made the plate, but that's certainly do-able.

Next question was: "Since I have to have the 3 1/8"-wide envelopes meet this exact spot, at these two stop fingers and the trip switch, is there a gripper on the impression cylinder that is in place to take it once it's through the imprression phase?" I ran one through by hand. Yes!
"Will it meet up with a gripper on the chain delivery's gripper bars?" Yes, right there! Perfect placement. Apparantly the machine was designed with this very job in mind.

So, I said to bossman "Yes, I can run these." "Are ya sure?" "Sure."

Thursday afternoon I grabbed a box of 500 envelopes and set the machine up to run them. I didn't want to waste envelopes, so I set the image in place by using some card stock that I'd cut down to size. The image was perfectly centered and the cards were running flawlessly. Time to start printing on the envelopes!


The envelopes went through just fine except for one little thing: the bottom flaps (the secured ones, not the open ones) weren't glued down tightly They were glued near the very bottom edge, but the whole flap wasn't secure and they were catching on the stop fingers. A whole pile of envelopes -- with perfectly centered images -- had mangled bottom flaps on the back. Dumpster food.

I lowered the stop fingers to try to have them drop below the loose-fitting flaps as the envelopes passed over them. Still catching. Still crap. I lowered the stop fingers some more. Still catching and tearing the supposed-to-be-glued-down-tight-but-aren't bottom flaps! I lowered the stop fingers until they were letting the envelopes fly through the elevator frame before the feed rollers came down to grab them. Bad.

I lowered the feed rollers to put them more in sync with the stop fingers. They grabbed them on cue, but too soon for the impression cylinder's grippers. Very bad. And to add insult to injury, the envelopes' flaps were STILL catching on the stop fingers. There was no way in Helsinki that these envelopes were going to run cleanly through the press like this. The only solution was to run them sideways -- so's as there're no supposed-to-be-glued-down-tight-but-aren't flaps to catch on the stop fingers.

There are several reasons why I can't run the envelopes through sideways. F'rinstance:
1) The back paper guide of the elevator (that keeps the pile of envelopes in a pile) can't get within 3 1/8" of the front guides (sheet seperators).
2) The paper height control bar hits at the very back edge of the envelope pile, causing the top of the pile to flop around rediculously.
3) The space between the pullout wheels and the guide belts is about 5", meaning that the pullout wheels are essentially tossing the envelopes onto the register board resulting in all manner of flappy, crooked, fall-as-they-may envelopes ambling through.
4) The guide wheel, due to the construction of the assembly and crossbars that keep it in place, can't get within 4" of the stop fingers.
5) The left oscillating register guide can only reach the last 1/4" or so of the envelope once it meets the stop fingers -- making the envelope not set squarely -- and the right spring guide can't reach it at all.

I actually did run some envelopes through just to see what would happen.

"Impossible," I told bossman Friday morning.

"Thing is," he said nervously, "I promised this job for next week. The most reasonable place that I can outsource it to said it'd take three weeks. The second most reasonable place would charge me more than I'm billing the customer. Try to find a way to do it, please."

Ooooookay. I can't run this job on this press. But, I have to. So, we go into McGiver mode.


[TO BE CONTINUED pork chops are done]

Posted by Tuning Spork at August 6, 2005 04:47 PM | TrackBack

What is the percentage of spoilage? It might be worth it to just buy enough envelopes to complete the order on time and eat the spoilage. Apply the lesson learned to the next time.

If its a good or potentially good customer it's worth the investment.

Posted by: Stephen Macklin at August 6, 2005 06:20 PM

Initially, the spoilage was 100%. The stop fingers just would NOT ignore the flaps.

Then I got an idea or two.

But that's in the to be continued... department... ;)

Posted by: Tuning Spork at August 6, 2005 08:23 PM

Not boring at all, machinery fascinates me.

Posted by: Ted at August 7, 2005 11:44 AM

I'm with Ted. No boring to be found here. That was totally interesting and I can't wait to hear if you solved the problem.

Also, cool looking machine!

Posted by: RP at August 8, 2005 01:10 PM

Thanks, guys! I tried to make it so yer eyes wouldn't glaze over. :)

Posted by: Tuning Spork at August 8, 2005 09:12 PM
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