Searching for an independent UV Printer Technician with CET experience

[MrNick86]

After today's experimentation, I discovered a few things to add to my previous post here:

So, could the negative pressure system have play in why I drop out with high ink demands, in particular magenta? Yesterday, as well as the last time I ran this job, I drop out about every 12 inches of rich red on a full 96 inch sheet. I jacked the negative pressure way up to 4.5 and it made it about 24 inches. That was with a 3 extract. I have struggled with figuring out why the FK512x drops out all the time.

Please help...

If you look into some of my previous posts, I have modified the negative pressure manifold to have high quality metal piston valves, I have capped one of the two inlet/outlets that go into the heads from the secondary's, eliminating the bleed tubes. I have also replaced all of the crappy plastic tube fittings with stainless ones and Teflon taped anything that could be taped. I basically have done everything possible to eliminate air from entering the system, it is completely sealed. I have had a fairly stable system until I have high ink demand. It is almost like the ink cannot keep a steady flow to the heads, especially quickly enough.

A couple other observations I have made are that I notice the negative pressure slowly increases throughout the day, even when I come in the morning and fire it up, it will be higher then I left it. Also, when I open a valve on the manifold and attempt to manually purge, the pressure cannot push ink through the heads unless I drop the negative pressure to the point where it would drop anyways. That pump has been replaced, no difference. Many parts and filters have all been replaced and I have seen zero improvement with these faults.

Ideas???

Mind you, this is all regarding printing a very rich RED. If I print this full sheet of red at 4 pass, bidirectional, on 720 I can make it all the way through without dropout. Of course it looks like crap because I have a couple nozzles out, but that is besides the point. If I print the same thing on 16 pass, bidirectional, 720 I dropout magenta anywhere from 12-20 inches into the bed. So here I am thinking that no extract gets me through without dropout, why not try 8 pass, unidirectional, 720 to relieve the nozzles being out and allow time for the ink to resupply on the returning pass. Guess what, drops out in roughly the exact same spot. This is totally bass-ackwards. I am at a loss. I cannot get a successful quality print off of this color.

I have experimented with negative pressure being sky high, but I feel like it is restricting the ink flow to the head and not allowing it to flow at the needed demand. With a bare minimum negative pressure, just barely keeping the ink in the heads has had the closest to best success, and allowing the ink to flow freely through the head.


Here was another observation:
If you refer to the attached photo, I managed to catch an entire pass of a left and a right pass of the red. What is up with the color difference in passes based off of pass direction?

 

[player]

Attached photo?

 

[MrNick86]

Sorry, the photo did not upload for some reason,. Trying again...

 

[gregwallace]

Sorry, the photo did not upload for some reason,. Trying again...

Looks like your yellow is acting up too. Does your printer have dampers? If you pause the printer right before the dropout and run a purge what happens? Does this extend print time before the dropout?

 

[MrNick86]

Feeling stupid & dumb

I discovered that the negative pressure magenta line going into the the secondary reservoir was slightly kinked. :Oops:
So, that solved the dropout issue. I ended up lengthening all of them to be safe. Fixing the kink also got the manual purge to work again. The pressure can actually climb high enough now to push the ink through the heads. Live and learn, I guess.

However, that separate color between passes still boggles me.

What is a damper?

 

[MrNick86]

Spoke too soon, the problem persists. I got lucky for a few beds.

 

[gregwallace]

We have a vutek and suffered with ink starvation issues for over a year. In our case it turned out to be the dampers. They regulate the flow of ink from our secondary tanks to the heads. If your negative pressure line has a leak or a kink ink will weep from the heads with no vacuum to hold it up.

 

[artbot]

the CET FK512 that i had for a year had horrible cyan starvation issues. it was a factor in the failure of the partnership that i signed in on. i heard recently that despite the new owner's attempts that the printer still has the same issue and the recommendation was to refurb the whole printer into perhaps a Q series!

as for the change in pigment from left to right vs right to left that is metamerism caused by the head order in bidirectional mode. in one direction the fore head vs the aft lays down dots in a different top to bottom order. so left will have yellow dots on top of magenta dots and the other direction will have magenta on top of yellow dots.

have you tried cranking the heat waaaay up? and do the heads hold consistent temperature. i think i remember that when we'd experience drop out there may have been a temperature relationship where temporarily the temp would fall and recover. this could be the head or the data to the head.

 

[Tekkie1]

Hi does this machine have led or lamp curing?
If lamp curing lubricate the shutter solenoids they may look like thay are opening and shutting poroperly but thay may not be.
I had this same issue on a machine that would give very different results in either direction. changing the lamp before or after switching gave very different results and it was actually better with the lamp turning on before curing, which goes against the general rules.
After finding that the lamp shutters were stcking and then lubricating them all was back to normal just like a new machine.
this machine had been used heavily for about 7 months before this problem happened.
Tekkie1