O.K., here's the deal. I've been a pressman for 25 years, have run everything from a Multi-1250, to a 40" 2-color Harris, to a few Heidelberg GTOs and KORDs, to a variety of 4, 5 and 6 color Komori Lithrones. Right now, I'm running a full-auto Komori L-628, with perfector, coater, scanner...the whole works. It's now 5 years old, and I've been the lead on the second shift for 4 1/2 of those years. We are a fairly high-end commercial printer and run typical stocks, usually ranging from 60 lb coated on the thin side, to 16pt on the heavy side. We rarely run anything outside of that range. On all presses in this shop, and on every other press at every other shop I've ever worked in, we NEVER regularly adjusted the swing arm gripper clearance unless the stock was something truly exceptional, like onionskin or board stock. And we never, ever, had a problem using the "standard" setting.
Until recently, that is. The swing arm on the 628 started making soft clacking noises, and while we tried to identify an exact cause of the noise, and made the obvious attempts at adjustment, we couldn't eliminate the noise. The swing arm eventually stopped accepting sheets properly. We had to call Komori in to investigate. They said we needed to replace the gripper pads and cam follower. They made the repairs, and solved the problem. They also said we were supposed to adjust the clearance setting for any stock thicker than 80lb/0.004. This means we get to move the press to the proper position, get out the wrench, and make the adjustment on basically every job we run. We go back and forth between 80lb and 100lb all the time - which are on opposite sides of the standard setting. We never once did that before (either in this shop or in any of the others) and the swing arm on this press ran problem free for 5 WHOLE YEARS.
My questions are: What's your take on this, do you adjust the swing arm clearance setting on your press daily? And, what's wrong with setting it for ample clearance and leaving it there, if it works for the jobs you're running? I realize some jobs or stocks may require a careful adjustment of the clearance setting for a wide variety of reasons, but Komori is apparently implying that we somehow damaged the gripper pads and cam follower by regularly running the gap too tight for the stock. I was taught (and I've seen it myself, firsthand) that the press will let you know instantly if the setting is too tight, by either damaging the sheet, causing mis-register, or bouncing the sheet out from the headstops entirely. How could I be wrong about this, after 25 years of experience? And how bad could a "too tight" setting be, if it took 5 years of 24hr/6-day run time to develop any problem whatsoever?
I'm not sure I've ever even heard the term "cover guide", although I can think of at least one type of apparatus on the L628 that it could be the proper name for - what we refer to as sheet flatteners. My first post actually refers to an adjustment located right on the swing arm of a sheetfed press. The adjustment effectively raises or lowers the swing arm position slightly to accommodate for the thickness of the stock. The Komori tech is saying it needs to be reset for all stocks thicker than 0.004". We've never done that before, except in EXTREME cases, and it worked fine for years.
Hi, I think we are Talking About the Same thing But its Called different things in Different Parts of the World. on the R700's they are Adjusted Automatically when you set the Printing Pressure at the Console. on other presses i have run i Rarley Adjusted it on paper from 115 Gram upto around 250 Gram and even then if i was to forget to adjust it i seldom had problems
"They also said we were supposed to adjust the clearance setting for any stock thicker than 80lb/0.004. This means we get to move the press to the proper position, get out the wrench, and make the adjustment on basically every job we run."
How high up the Komori service organization have you pursued this? And what does the manual for this particular model have to say on this?
The cover lay is sometimes also referred to as the hood lay, and on the '00 Komori 40" I run they are small chrome covers that run from the head stops and effectively cover the first 5mm or so of the grip edge of the sheet, with the purpose being to stop the sheet from riding up over the head stops. They are adjustable under the feed table with a 13mm spanner, and generally a setting of about .4/.6 (could also be .04/.06!! cant remember right now!) will suffice for almost any stock the press can handle.
The only time i have really adjusted the cover lay is when running heavy board (ie 350gsm+), or when running super light stock, as even with lightest possible feedtable brush wheel setting light stock can ride up slightly in the lay and give you bounce and fit issues.
We run the swing arm gripper setting at around .03 all the time, as the minimum setting on the guage equates to .03 so effectively a setting of .06. The only times it requires adjustment is when going to heavy stock that snags slightly in the grippers and wont pull over and register correctly, or on very light stock where too wide a gripper setting seems to result in creasing of the sheet. This can also result in a bit of run in and paper stretch making fitting the back corners a nightmare.
I dont think you have done anything wrong at all, did they look at the swing arm cam follower whilst they were fixing the grippers? Its possible, but not likely that the bearing and cam may be slightly worn and affecting the gripper timing etc.
The adjustment I'm referring to is not to the "cover guides", as they are described above. I have adjusted these before from below the feed table, although very rarely, and not on this particular press (yet).
The adjustment I'm referring to is on a dial located directly ON the swing arm itself, accessed from above the headstops, on the op side. It can only be accessed at a certain rotation position of the press. There is a locking nut, and an adjustment nut. After unlocking the first bolt, the same 14 mm wrench is used to turn a second bolt, which has a reference mark, up or down a dial. The "standard" setting and the minimum setting are numerically indicated on the dial, with other increments also shown but not labeled, mostly above the standard setting (i.e., for thicker stocks). To the best of my recollection, most other shops I've worked in have found a workable setting greater than the standard setting, and left it there for 99% or more of their jobs, the idea being to make it wide enough to accept every normal stock, but not so wide as to potentially cause issues with the thinnest stocks they run.
That's what I've always done: found a point where it worked well for basically everything, and left it there. To me, the idea of stopping a fully automatic press and making a manual adjustment like this on practically every different job is ridiculous. If this adjustment really was supposed to be made all the time, they would have found a way to automate IT, too. It just doesn't make any sense, otherwise.
I have not pursued this with Komori beyond the tech who worked on the press. He's a good guy, and I'm familiar with him, although I didn't personally talk to him this time (I'm on the night shift).
The manual says the exact same thing the tech did...as far as I can tell. Komori manuals are horrible, although they have been getting a little better over the years. It's as if a German translated it into English from the original Japanese using one of those little translation books. It's usually not very clear what they mean. But the manual refers to the same numbers the tech did. I'm sure he has no choice but to give us the standard numbers out of the manual; he probably can't recommend a setting that isn't to spec. I think that is basically Komori "covering it's butt": they don't want to tell you to do something that could eventually screw up a run. They would rather tell you to leave it at the standard setting for thinner stocks, and adjust it accordingly when you run any thicker stocks.
That doesn't mean anyone HAS to do it, however. What I'm getting from you guys, so far, is that you don't make the adjustment I'm talking about very often. Every press I've ever run (that had a swing arm in the first place) had the same sort of adjustment dial on the swing arm. But I've only felt it necessary to make that adjustment about 3 or 4 times in 25 years, for extraordinarily thick stocks.
I'll be back soon to check for further comments. Thanks again. I'll get to the bottom of this, one way or another.
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