Presstek 52DI

[wcisme]

Re: Presstek 52DI

Hello,

This is my first post, and first time looking around this site.

I would have to agree with most of what has been said about the 52DI. We installed one in June of this year and although much of the work looks great, we have had quite a long list of issues. I am hoping for some help with one major issue we have had since the install, so here goes.

We are in Kansas City MO, and i demo'ed the machine in a shop in St. Louis. I spent the whole day with the owner, the operator, and the prepress manager. They are very happy with the machine and the work is has produced. So much so, they just added another one. They are using the Nexus workflow.

We purchased the Harlequin Momentum RIP with the 52 for a couple of reasons. The main one being that we had no litho machines till this. We have a pair of Digimasters and a Nexpress. So the way we saw it, we wanted something simple and inexpensive to make the 1 bit tiffs for the press.

The main problem we are seeing is a somewhat complicated issue i believe, and we are still not sure if it is RIP related, or mechanical on press. Morie's and strange patterning in screens. We have tried all the usual traditional things to rectify this to no avail. We have figured out some work around's to keep the jobs moving through, but these are not long term solution's.

We have been running 300lpi on coated stocks and 175 on uncoated, 2540 dpi, euclitian dot shape. We have been using 2 different screen angle sets. One set is the traditional angles (15, 75, 0, and 45) default on the rip, and one is a set that Presstek gave us to try. (Not sure the exact angles off the top of my head. I'm at home).

The reason we were given the second set of angles to try is that the black unit will not run a 45 degree angle without a corduroy pattern in all values of screens. ?? We still have not been given a reason why after many a screaming match. The traditional angles, even though the black has the pattern in it *will* run on certain jobs. I still see some grainyness in the 3 quarter tones, and over all quality is average, but they dont morie.

The second set of angles look really good, considerably better than the traditional angles in fact, when the morie doesn't pop up. When it does show itself its bad,...very bad. When it does show, we use the traditional angles. This has been a every couple of days problem for us. The field engineers are lost, so am I.

Supposedly engineers are working on this in NH. I believe there is a problem with the press on the tower that burns the black and magenta plate, I have spoke to other installs and they are able to run without seeing the pattern in the black.

Thanks for reading, if you need more detailed information let me know, and if you have any ideas it would be much appreciated.

Thanks in advance,

William Mitchell
Kansas City Digital Press

 

[Guest]

Re: Presstek 52DI

William,

I feel your pain! The moire is probably a rip issue, but the "corduroy" pattern is most certainly a press problem. If the pattern is parallel to the cylinder axis and the spacing of the lines is the same as the pitch of the cylinder gears, it's my old friend the gear streak problem. I cut my teeth on an old used Chief 22 that had the problem big time back in the late 60's. It showed up on screens AND solids with either normal or low tack inks, and could be masked with high tack inks. This was with molleton dampening and conventional albumen plates burned from camera films.

You probably have a mild version of the problem, and it is first imparted to the screens as they are imaged on press since the same gears are involved as when printing. Later on when printing, the problem recurs and reinforces the pattern burned on to the plate. Otherwise why only the black unit, and why only in your install? The challenging difficulty in manufacturing precision gears for printing presses is well known. It's your bad luck to have ended up with a substandard one in your machine. Test this idea by reducing the ink a little and watching the problem worsen. Then do a thorough wash up and repeat the test with high tack ink and the problem should lessen.

As for a real solution, stop making payments, and enforce the contract on the seller. Simply put, they must replace the press! Sorry I can't make a more positive comment.

Al

Edit: To learn more about this do a Google search for "gear streaks in printing."

Edited by: Al Ferrari on Dec 29, 2007 11:38 PM

 

[[email protected]]

Re: Presstek 52DI

William,
Can you see the pattern on the plate? Maybe a cylinder has end play? Or form rollers etc?
Are your blankets ok? Are they tight? What happens when you run just the unit with the problem?
There are probably pre loaded test screens on the DI you could output and by pass the rip have you asked the Ptek boys about that? Nice test would be a 300 screen all fours colors from the DI directly.
Presstek just laid off many service techs so it may be hard getting one to your site. They seem to be counting beans and parts and the stock holders are not happy.
Best of luck
©G

 

[wcisme]

Re: Presstek 52DI

Thanks guys,.....I think.

Yes there are files on the press that came pre loaded, and I have run these as well. The worm dens test? The same problem appears. It was noticed during the install testing and they replaced the main spindle and belt. They said it was caused by vibration. It was for not. The lines run around the cylinder and yes the blankets are good and tight. I have burned the black plate in the cyan unit and there is no sign of the problem. You can only see the problem on the plate after it has been inked up and some sheets have been run, not right after burn and plate clean. It looks like the same pattern thats on the plate cleaning towels. The plate cleaning in general has been thought to be the culprit up till the last few weeks.

I can trade the angles with cyan and the problem disappears. Although the overall grainyness of the printing is there, and obviously this is not a fix. Just like the new angles they gave us,....just a band-aid covering up the real problem.

I sent many printed sample and RIP'ed files to NH, and on friday I did get conformation from the Tech testing my files that his worm dens test did not look like mine. Although the new angle files I gave him did morie like mine. He was careful in what he was saying as I'm sure they are all in CYA mode. He did mention that it could be that the first tower laser was "out of focus" a bit. ?? So here I am with 2 angle sets and neither will work.


The last few months have been painful, and I must admit I'm not feeling warm and fuzzy Al. We are prepared to take legal action, it has been discussed, I just want to have all my ducks in a row.

Thanks so much for your responses. Any more info would be great.

William

 

[Guest]

Re: Presstek 52DI

William,

If the lines run around the cylinder, then dismiss my suggestion that it may be a gear streak problem.

So what could it be? From the info in your last post I would guess it is an imaging problem, not a printing problem. Does an imaging head actually travel across the plate during imaging, or are there multiple diodes across the plate? If an imaging head is moving across the plate during imaging, it seems that there is a stuttering vibration in that motion. If it is multiple diodes, then they may be picking up a vibration from some source, and if the focus is not optimal that could be the cause of the banding. Except, why would all diodes be equally miss focussed? Have you tried to detect a vibration during imaging in that unit that is not present in the others? Just a guess.

Al

Edit: As for having your ducks in a row before taking action: it is not performing as promised, you have given them the opportunity to fix it, and you are loosing money and going through grief. What more is needed? They should remedy it with a replacement. It's that simple.

Edited by: Al Ferrari on Dec 30, 2007 2:09 PM

 

[wcisme]

Re: Presstek 52DI

Al,

I would agree it's imaging. If it's vibration why not show up in the second tower? Yes there are multiple diodes. I believe there are 12, not sure.

The vibration issue has been looked at, and they replace the worm spindle and belt. They admitted they had seen this before, and the replacement would fix it. There was no difference. Friday was the first I had heard of the laser being out of focus, and like I said before, the tech was very careful of his wording and information he was willing to give up. Not sure how the lasers are focused and what mechanical adjustments can be made. Maybe an overall adjustment?

It's a mystery at this point and the worst part is it's been there since install in June. I made a huge deal about it in the beginning because I just didn't understand why we couldn't run a 45 degree angle in black without the anomaly. How many years has black been run at 45??? They have already stated they thought we "fixed" the problem with the new screen angles. I don't know about you but 1 in 5 jobs with a morie is not a "fix".

Thanks again for all your input.

William

 

[Guest]

Re: Presstek 52DI

William,

I am participating in this discussion out of general interest, but as I do not have experience with this machine, I have no concept of what the worm spindle and belt are. Can you explain a little about their function? It may stimulate some idea from your readers.

Al

 

[wcisme]

Re: Presstek 52DI

Al,

I'm sorry. To the best of my knowledge, the worm spindle is the piece that drive's the entire press. It spins, and the belt attached to it turns the press. Both during imaging and during impression. It was replaced, and we were told that this should "stop the vibration", which they believed was the problem. Also we were told proper tension of this belt is of top importance. This has been checked and r-checked numerous times. Seems this is a known problem with the 52DI now. Just didn't make a difference in our case. I really have lost a lot of confidence in the field engineers we have in our area, and it could be this tension or belt is *still* the problem? Getting tiered of shoulder shrugging. I want some answers.

This whole thing came to a head this last week. Because of several major changes at our shop we were not able to take the time to push for a resolution to this problem. Testing time down time, and the like have been put off because we just moved into a new facility. I'm sure anyone who has moved a small shop knows how difficult that can be. I now have several jobs that just won't run to the expectation of the client. We are looking like fools and that makes me angry.


Thanks again.
William

 

[[email protected]]

Re: Presstek 52DI

William,

Wow vertical banding. Have they considered swapping the lasers from unit 1 to unit 2 etc?
I agree the traditional screen angles are K 45: M 75: Y 90: C 105. Do the registration targets line up in all 4 corners? No image fit problems? You mentioned you saw a demo close by to you, have you asked them to print a file for you? I would call them and ask if you can send a job over and see what results they get using your settings and their settings etc. I mean you spent the day at the demo shop and saw printed sheets coming out and you were impressed enough to buy a DI so maybe they can offer you some insight.
What have the local techs told you? June install and still problems? HMMMM Have they brought the Ryobi techs in from Japan yet? I am sure Ptek will solve your problem somehow, posting here will defiantly help your cause .
[http://en.wikipedia.org/wiki/CMYK_color_model]
Not a bad read
Keep us posted and Best of Luck
OG

 

[Guest]

Re: Presstek 52DI

William,

From what you say about the spindle worm and belt, that can't be the problem since that would affect the whole press, not just the black unit. Clearly your machine (ahem, their machine, since it's not paid for yet) has a unit specific problem. In this regard, the suggestion by Offset Guy to test by swapping the black laser with one from another unit makes a lot of sense. Also swapping other components from the problem unit and a working unit.

Al

 

[wcisme]

Re: Presstek 52DI

Guys,

Swapping lasers has not been done or suggested yet. Great idea. The color to color fit is amazing. Perfect really. I moved the plate to plate register one time since install and it's very consistent. I'll have to give them that one.

I have talked to the shop in St louis, operator and prepress manager, on Friday, and they will run files, or RIP files for us. This is what we will be doing tomorrow morning.

I will say this too, some of the work coming off the press is really great. It totally depends on the content being printed. Problem is, we don't control the content, do we? So finding something that will be a consistent and reliable way to produce jobs is what has to happen,...right now.

Also, I mentioned in an earlier post the worm dens test. This is the test file thats run on both towers black and cyan. Its the test you run to adjust the lasers. Basically its some solids and screens that are printed from both towers, you then have to, by eye, adjust to all appear the same value. You do this through the front end of the press in number values. You see the problem in this test in black. It was sent to NH, and this is what the tech told me did not mach. Said his didn't have the pattern.

Thanks again.
William

 

[[email protected]]

Re: Presstek 52DI

How are you making out William? Did The laser boys hook you up? They can not afford to have customers not satisfied.
They just raised prices on supplies also, LOL. When the stock price is down they raise prices. Razor and Blade Theroy.
Any way let us know what happens?

 

[GraphicGuru]

Re: Presstek 52DI

I see that this thread is an ongoing topic. So I hope to revive it with my issue. The shop I work at has a 3404 DI the basic model.

We have had problems in the past with an older harlequin rip and have updated to a Xitron Xenith Extreme RIP, so our Workflow is fairly new and reliable. We also had the press fingerprinted after the Xenith system was installed - all good there. We were in the process of trying to make sure our contract proofs could be matched on press. Worked out pretty good. Until...

Here is the status of the location of the 3404 DI. It is in the press room with 2 other traditional one and 2 color presses - 3302 & 3200. There is also a paper cutter and the main garage door about 15 feet away from the DI. Basically not in a controilled room. Our DI does not have the auto INK key System. Our DI has two towers, and 2 doides each diode having 6 banks.

Here is our problem:
About 2 months ago there was a strange line occurring inbetween the 5th and 6th diode bank on the first tower. We rotated the image and still have the problem in the same spot. Project MAnager and I spoke aobut the culprit being the file. To No avail I explained the fact that the Xenith system is giving the file as it should print to the DI, but the file is getting imaged differently than the Xenith system is showing. Taking the files after the DI has imaged them and sending off to support has verified that the 1-bit tif is exactly as it should be. My statement back then was there is a laser problem. The problem reoccurred only on this particular file. It may not have shown up on other press runs as other files did not fall into the area where diode banks 5&6 met on the first tower. We ended up rotating 90 and printing it that way thus avoiding the 5&6 bank on the first tower. Job printed fine that way! Now I went back to 4 other print jobs before this one problem, and I noticed it was there in those runs, so thus verifying again that the Files are not the culprit.

This seems to be a problem in a file that contains a tonal value of each of the CMYK colors. Meaning that there is not a 100% build of any one of those - CMYK.

OK, so we had the tech out and he was totally stumped. The owner here gave some suggestions and the tech stated that may be part of the problem (is it the Diodes or the power supply change we receltly did?) - Are we to get paid this guys salery if we are giving him the answers?? - NOPE! He stated he would get back to us with some answers, but no soild answer from him to date - still 2 mths later.

At any rate Support from our RIP is stating we need an "expert" to come out. I have suggested this to my employer, but he states that there is no one better than the guy that has no idea of what is going on. Besides the guys in Kansas - or even Japan (AS I SEE OFFSET GUY HAS ASKED of others here...). I would love for the guys from Japan to visit our small shop to see that we are throwing away plates daily - due to press/machine issues!

Again last week a job came in to us with gradients. Now this one stumps even me. I use a one up PDF with color at the bottom of the 5.5x8.8....then impose 2up using Dynastrip and then use the xenith extreme to rip the files to the DI. Well this particular job is a Post card folded down to 4.25x5.5 - basically the file has fair amount of coverage at the grip and not so much at the tail...... What has happened this time is that the second stepped file on the right hand side of the press sheet has a solid going across the piece and the one on the left is like the contract proof showing the gradient. This is mostly predominant in the Cyan plate. So we rotated 180 and this time (different from the file issues 2 mths ago) the solid went to the upper left.. and the one on the upper right is like the contract proof. AM I GOING CRAZY YET? You bet.

I get on the horn with Xitron and send them the files.They verified that the files even after going through rasterhblaster (a 1-bit tif catcher converting the 1-bit tif to a language the DI can understand for imaging) are accurate and that there is something going on with the press.

I for one think it is related to some of the same tpoics dicussed in this thread. We are near a train track and I sit on the second floor - when the train goes by the building shakes!! Like a minor earthquake - This makes me think a vibration issue could be doing something to the laser (diodes). The other factor is that the temperature where I work is for the most part stable, but can fluxuate dramatacally when it rains. Being in the Pacific Northwest has its benefits as well as downpours!

I have stated over and over again that this is most likely the main issue - the humidity. I have aksed to get a device to show the Temp/Humidity in the press room, so we can corrilate the two together - error on plate - humidity out above or below range of acceptable for the device etc...

The owner is not able to make this drastic of a change for this press - Converting the room into a controlled environment.

I am at an impass. Any thoughts from other DI users out there.

I am doing my best to make sure I show what I find to the power people involved with the decision making, but they are not understainging or wanting to listen. SO, I know I have done my job to the best of my ability I just have to keep my lips seald when isses continually arise, and my suggestions are not taken seriously as a solution to the problem. I mean how do we know if doing the controlled environment idea would work unless we tried it?

Thanks in advance for any thoughts on this matter....

 

[John Roberds]

Re: Presstek 52DI

Two comments:

If you rotate the image and the line is in the same position on the sheet, check the diodes. If the line moves with the image, check the rip.

Trying to run a DI with waterless inks without controling the temperature in the room is asking for trouble. You will spend more money on waste and re-prints (and pain killers for the headaches) than it wil take to set the room up properly. No way aound it.

John