QTR-Quadtone RIP

I had such good luck with my question the other day, I thought I might push that luck with the "big one".

With Epson's smaller K3 printers, the ones that have the pinwheels and also the rubber wheels that push (or drag) the paper through the machine, under the right circumstances an effect I refer to as "skid marks" or "railroad tracks" (same thing) occurs. I am referring to the SP 3800/3880 and their smaller thirteen inch brethren.

These marks might be described as 'chatter' lines, as if the paper were perhaps slipping and then being recaptured. The lines run perpendicular to the paper path, seem to occur right where those rubber rollers touch the material. Lines are about 2mm (roughly) apart and generally run along half the length of the print.

They occur in from one to several groups across the print, but never where all the rubber rollers are, just some.

They also look as though ink were getting pushed in front and then left behind and then picked up yet again.

Also, this problem appears to be humidity related. People who live in humid climates report it a lot. Here in Arizona, I see it seldom enough that I can't get sufficient repetition to really study it.

This is occurring with a smooth surface material.

I have devised some techniques that seem to provide improvement, but no cure.

Things that I know are definitely NOT the cause:

the pinwheels (front feed is used)

slow ink drying

dirty rollers

failure to swing a dead cat at midnight

This may actually be more head-alignment and dither related than roller-related . . . verify head alignment and print with the epson driver (with a similar ink load) to ensure that these same tracks actually appear in that environment. If they don’t, you know it’s something about nozzle timing. Improper nozzle timing or weave/dither errors can cause something very similar.

Best,
Walker


> On Oct 26, 2018, at 10:18 AM, david@davidkachel.com [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> 
> I had such good luck with my question the other day, I thought I might push that luck with the "big one".
> 
> With Epson's smaller K3 printers, the ones that have the pinwheels and also the rubber wheels that push  (or drag) the paper through the machine, under the right circumstances an effect I refer to as "skid marks" or "railroad tracks" (same thing) occurs. I am referring to the SP 3800/3880 and their smaller thirteen inch brethren.
> 
> These marks might be described as 'chatter' lines, as if the paper were perhaps slipping and then being recaptured. The lines run perpendicular to the paper path, seem to occur right where those rubber rollers touch the material. Lines are about 2mm (roughly) apart and generally run along half the length of the print.
> 
> They occur in from one to several groups across the print, but never where all the rubber rollers are, just some.
> 
> They also look as though ink were getting pushed in front and then left behind and then picked up yet again.
> 
> Also, this problem appears to be humidity related. People who live in humid climates report it a lot. Here in Arizona, I see it seldom enough that I can't get sufficient repetition to really study it.
> 
> This is occurring with a smooth surface material.
> 
> I have devised some techniques that seem to provide improvement, but no cure.
> 
> Things that I know are definitely NOT the cause:
> 
> the pinwheels (front feed is used)
> 
> slow ink drying
> 
> dirty rollers
> 
> 
> failure to swing a dead cat at midnight
> 
> 
> 
> 



[Non-text portions of this message have been removed]

Walker,

Thanks, but I think we can safely rule those causes out. (I hope.)

Until just a day or two ago, it was not possible to test with the Epson 
driver as QTR was completely necessary for this work.
I can theoretically test it now with the Epson driver, but I don't think 
that will solve anything, and I cannot force the problem to occur so 
have now way of knowing if any testing of the Epson driver is giving 
valid results. I forgot to mention that when this does occur for me, 
running two or three prints through the machine makes the problem go 
away. In more humid climes, it persists much longer.

Even if the Epson driver solved the railroad track problem, it wouldn't 
solve the problem. ;-) If using the Epson driver works for RR tracks, it 
is still too ham fisted a tool for this kind of work on a regular basis. 
Only QTR is sufficiently sophisticated.

If you mean choosing a different kind of dither in the QTR driver, that 
didn't work either.

Also, this problem does not occur with Epson's larger printers, only the 
smaller ones.


On 10/26/18 8:37 AM, 'forums@...' 
forums@... [QuadtoneRIP] wrote:
> This may actually be more head-alignment and dither related than 
> roller-related . . . verify head alignment and print with the epson 
> driver (with a similar ink load) to ensure that these same tracks 
> actually appear in that environment. If they don\u2019t, you know it\u2019s 
> something about nozzle timing. Improper nozzle timing or weave/dither 
> errors can cause something very similar.

-- 
David Kachel

_________________________

Artist-Photographer
Fine B&W Photographs & Photogravures
Inventor of Selective Latent Image Manipulation Techniques

Walker,

I imagine so. What I am really printing on is a 50 micron thick dry 
photopolymer on a PETG plastic base.

I have never see it on actual paper.

On 10/26/18 9:23 AM, Walker Blackwell forums@... 
[QuadtoneRIP] wrote:
> I have a lot of experience with this printer and it\u2019s very rare that I 
> see this problem. (Like one out of every 500 or 600 prints).

-- 
David Kachel

_________________________

Artist-Photographer
Fine B&W Photographs & Photogravures
Inventor of Selective Latent Image Manipulation Techniques

Hmmmm. OK, changing roller pressure is an interesting possibility. How 
does one do that?

On 10/26/18 11:18 AM, Walker Blackwell forums@... 
[QuadtoneRIP] wrote:
> Oh. Well that explains it. This variable was not explained (or was 
> it?). These printers are not built for that material. You will need to 
> change the roller pressure manually somehow and you will also need to 
> control your humidity.

-- 
David Kachel

_________________________

Artist-Photographer
Fine B&W Photographs & Photogravures
Inventor of Selective Latent Image Manipulation Techniques

Most likely nobody has ever significantly attempted to do this . . . you would probably be the first one.

-W

> On Oct 26, 2018, at 1:40 PM, David Kachel david@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> Hmmmm. OK, changing roller pressure is an interesting possibility. How
> does one do that?
> 
> On 10/26/18 11:18 AM, Walker Blackwell forums@walkerblackwell.com <mailto:forums@...>
> [QuadtoneRIP] wrote:
> > Oh. Well that explains it. This variable was not explained (or was
> > it?). These printers are not built for that material. You will need to
> > change the roller pressure manually somehow and you will also need to
> > control your humidity.
> 
> --
> David Kachel
> 
> _________________________
> 
> Artist-Photographer
> Fine B&W Photographs & Photogravures
> Inventor of Selective Latent Image Manipulation Techniques
> 
> 
> 



[Non-text portions of this message have been removed]

Oh, wonderful. First guy in the minefield!� ;-)

I don't suppose closing the platen gap would have any effect?


On 10/26/18 1:20 PM, 'forums@...' 
forums@... [QuadtoneRIP] wrote:
> Most likely nobody has ever significantly attempted to do this . . . 
> you would probably be the first one.

-- 
David Kachel

_________________________

Artist-Photographer
Fine B&W Photographs & Photogravures
Inventor of Selective Latent Image Manipulation Techniques