Well, the management finally decided to calibrate our plates to the presses.
Our Komori 5 colour was measured and calibration curves were input to the rip for each of CMYK.
Our Komori 4 color pressman was away on holidays and his press did not get calibrated, he's been running linear plates for years with no big complaints. Boss says give him the same curves for the plates as the 5 colour but he is having a hell of a time making his work look good now. We have had to bump up his calibration curves a lot for him to get good colour. We're still trying..... next trial is a dot gain in the 50 percent area of about 8 percent. The other press is about 18 percent which seems about normal. Both guys are running the same Agfa Azura plates. They are running up the proper ink densities on the color bars....up to spec.
Question is.... could 2 presses be so far apart in the calibration curves they require?
Even a simple yep or nope would help. Providing you know what you're talking about. :banana: :drunk3:
short answer is yes.
2 presses, even if they are identical and the same age, will print different. You will need to calibrate each press to a standard, and yes, they will probably need different curves.
I can understand how they could each need separate curves, but such a big difference? Doesn't seem to make sense somehow.
(one dot gain at 50 about 18 percent, one about 8? This guy used to run plates with no calibration on them at all and made it look good. Never used color bars like the other pressman).
Maybe we should just give him the plates with no calibration applied.
Ahhhh...the old calibrate one press and use those settings for every press to save money trick. Never has worked. Never will work.
Yeah, I figured as much.
Can't say I am not suprised. :banghead:
Quote from: pspdfppdfxhd on August 10, 2017, 11:08:22 AMI can understand how they could each need separate curves, but such a big difference? Doesn't seem to make sense somehow.
(one dot gain at 50 about 18 percent, one about 8? This guy used to run plates with no calibration on them at all and made it look good. Never used color bars like the other pressman).
Maybe we should just give him the plates with no calibration applied.
when is the last time he checked his blankets?
is the press maintained to specs?
checked the ph?
The fact that he runs "without colorbars" means you have no idea what the press gain is even on a good day. It's a crap shoot.
Yes, I am not the guy to ask these questions, there are much smarter people around here than me about such things.... :drunk3:
Question: Does anyone on here run linear plates? (like the 50 coming out 50)..... AGFA Azura plates.
It really depends on what your standard is. It could be an in house standard/target or Gracol or ISO or SWOP or other. This will direct what the dot gain is based on the paper and ink combination along with the many other variables. A linear plate will print with the adherent dot gain but will that meet the target? If not, then you need a curve to achieve it.
Best,
Mark
Yes, the one press that was calibrated correctly was done with the G7 method. Basically it was balancing out the greys on the press. For a simplified example, printing a 50 percent black circle on top of a 50 cyan, 40 magenta, 40 yellow square and making them look grey like the black circle.
We have 2 nearly identical presses that are just 2 years apart in age and we have found that they will drift apart. Maintenance is key.
We need to run one curve for these because work will often bounce from press to press after jobs are plated. The two presses can also run in tandem.
We have another press that has had an aggressive curve in the yellow for years. We were pulling 15 points out of the yellow in the 50 and sometimes they needed to lower density to match a proof. They went through the unit and replaced almost all rollers, we fingerprinted again and now we are adding slightly in the yellow at the 50.
John
Well that pretty well says it all.
Thanks.
Quote from: Joe on August 10, 2017, 12:02:31 PMAhhhh...the old calibrate one press and use those settings for every press to save money trick. Never has worked. Never will work.
Yet it worked well enough in the place I used to work. There was a single curve for all 6 presses and we didn't change a damn thing when they bought 4 new ones.
Not saying it was right but having curves for each press would never work there. They would hop jobs around from press to press constantly.
They also caved in to their salesmen when they insisted they needed a dot accurate proof. Much $$$ later we had a Creo specturm. Few months later as we were using it for basically just dielines.
Through trial and error, we've ALMOST gone back to linear and the 2nd press.
Cyan linear, MYK just a small cutback, about 45 percent at 50 like a rubber band going from 1 to 100.
Doesn't make too much sense to me but it's working ok.
Quote from: Farabomb on August 14, 2017, 06:15:12 AMQuote from: Joe on August 10, 2017, 12:02:31 PMAhhhh...the old calibrate one press and use those settings for every press to save money trick. Never has worked. Never will work.
Yet it worked well enough in the place I used to work. There was a single curve for all 6 presses and we didn't change a damn thing when they bought 4 new ones.
Not saying it was right but having curves for each press would never work there. They would hop jobs around from press to press constantly.
They also caved in to their salesmen when they insisted they needed a dot accurate proof. Much $$$ later we had a Creo specturm. Few months later as we were using it for basically just dielines.
Hey we do it here with 4 out of 5 web presses. Still doesn't make it right. :rotf:
We have a "new to us" ManRoland web press being installed right now. They say they are going to be G7 certified on this press.
Me: :lmao:
Quote from: pspdfppdfxhd on August 10, 2017, 12:45:27 PMYes, I am not the guy to ask these questions, there are much smarter people around here than me about such things.... :drunk3:
Question: Does anyone on here run linear plates? (like the 50 coming out 50)..... AGFA Azura plates.
When using conventional packaging ink (i.e.: not UV), our plates are almost linear for both the CD74 & the CD102.
Well here is an example of the calibration of the magenta plates (other colors are similar, only the black is slightly non-linear on one press).
Well it works, seems to keep both pressmen happy so why argue with something that makes no sense to me?
(http://i.imgur.com/S0Z2W7j.jpg)
Joe or anyone that has used Nexus - wondering if I can tap your memory to the Nexus days. We are trying to update our cal curves from FastCal to Symphony. We have everything working except spot colours. Every test we send the CMYK goes ok, but the spot colours fail (no curve chosen) even though we have designated a curve to use. We can get it to run by choosing the spot colour tif in the workflow and picking the curve manually, but I'f like it to pick it up automatically, like it is doing for CMYK. Any ideas?
This seems to be what we are getting right now:
Oh man that has been 8+ years since I used Nexus and I can't even remember what I had for dinner yesterday. I do remember using Nexus and we were using Symphony and we did output spot colors occasionally but I don't think we ever had a problem in doing so. Sorry.
That's ok Joe - sounds a lot like me. We never did get the spots to take the curve automatically, so we did it the old-fashioned way and created separate curves for CMYK & spot and directed each to it's own proprietary curve in the workflow. It does work in kind of a late '90's way.
:cane: