squeegee pressure on an auto

[mooseman]

can anyone kinda quantify the amount of squeegee load an auto applies to a print stroke please.
i have never seen an auto live, in action outside of a show and there is this bug up my butt theat really wants to how much more pressure an auto applies relative to a geek like me on a manual.
Highly subjective , I know , but I do not have a clue and would like to get one . THANK YOU ......mooseman
PS I am good with the consistency that auto delivers but it  is the load element I seek...........................

[spotcolorsupply]

I may get corrected here... But I believe it is about the same as you would use on a manual relative to mesh count. Screens, ink, and squeegee don’t change. The goal is to clear the mesh in one stroke. An auto is just more consistent, and doesn’t get tired. I will say auto printers do typically print on higher mesh counts because the machine is capable of putting down more pressure (consistently  ) than a person can.

I have a stroke cylinder mounted above my screen stretching table that is used to apply downward force on the mesh in the center of the screen; using a square of MDF/Melamine as a plate (Does that make sense?). When I first set it up I used a UPS scale to see how many pounds of down force it was capable of. I was quite surprised; it could put down anything from 0 to like 80 or 90 lbs depending on the PSI I set it at.

I guess what I am saying is an auto can out do a person on high mesh counts, due to the extra force it is capable of... 

[bimmridder]

I bet Alan chimes in on this one. I don't get too hooked on what a regulator says. There are enough variables to make me just want to look at print strokes. Squeegee angle is a big one. Off contact another. Go deeper. Squeegee length from holder. Platen height (there is a lot of height adjustment on press set up, if that makes sense) To answer your question, 25-40 PSI.

[spotcolorsupply]

Actually I just went and checked.... 120 PSI = 155 Lbs on a UPS scale. I could have kept going, but the scale maxes out at 158 

[blue moon]

I think the pressure on the auto is a little deceiving as there is a physical limit to the distance the squeegee can travel. What happens when you set the travel to go past the mesh but not hit the platten? There's some very funky physics going on with the pressures.

I believe we are pushing too hard, but if we back off, the ink is not clearing. From my very brief manual printing days, I think I was able to push with considerably less force than these days and still clear the screen. Maybe it is just an illusion as we are printing through higher meshes on the auto . . .

pierre

[ebscreen]

1-6 bar. Human equivalent of being able to just kiss the platen, but also fold a 70 duro squeegee
in half.

I have noticed that the heavier fellas tend to make pretty good manual printers. Not sure if that
means anything or I'm just self conscious about my buck and a half.

[spotcolorsupply]

1-6 bar. Human equivalent of being able to just kiss the platen, but also fold a 70 duro squeegee
in half.

I have noticed that the heavier fellas tend to make pretty good manual printers. Not sure if that
means anything or I'm just self conscious about my buck and a half.

Note: for us dummies 1 bar = 14.5 PSI 

[ZooCity]

I've wondered about this too.  We're all-manual here.  I push stroke and honestly, unless we're talking a large open area through a finer mesh, the pressure is very light to me. 

What wears me out is hucking our 8/8 chameleon around and around and also holding the screen up while I do the hard fill stroke.  I put way more work into the fill stroke.  The print stroke is just clipping the ink off more or less.

[tonypep]

Contrary to some statements there is no one setting for pressure whether its PSI or old school twist and lock. This will depend on blade profile, durometer, unsupported height, angle of attack, and speed of travel. Then there is mesh count and tension, ink rheology, and off contact. There's probably more interdependant factors but that's enough variables to think about this early in the morning.
Seasoned press ops know how to "read the screen" in order to determine all this. Ideally when the stroke is completed you should be able wipe your finger across the image area and have it come off with practically no ink on it. If you are achieving proper shear and insufficient coverage you may wish to go back to the other variables and re-asses your pre-press. The quick bandaid is to double stroke.
tp

[inkbrigade]

I believe we are pushing too hard, but if we back off, the ink is not clearing.

pierre

Story of my life dude.

[alan802]

We usually print between 18-40 psi from 83 mesh to maxopaque ink through a 305 at 40.  I don't know how to relate psi on an auto to actual force from a human being.  I do have lot's of thoughts on print pressure but it doesn't really apply to the question.  I'll sum it up like this, why print with 30 psi when 22 will clear the screen?  You'll get more opacity from your ink, a better ink deposit, and countless other benefits from less wear and tear on your massive press investment to more life out of your stencil and screen mesh.  Now that I'm not on the auto all the time, I'm constantly dialing down the printhead pressure and pulling the squeegee up higher when I go check on the jobs being run, and my guy just doesn't get it.  I know not all autos are the same in that 35 psi on my press might equal 40 psi on a sportsman, but as long as your printing with an amount of pressure that is light enough to where it won't clear the screen if you were to change the central off contact a little bit, then I think you're doing it right.  The few different autos I've used, like our centurian, we were in the high 20's to 50 psi but I wasn't near as experienced on the ink transfer process. 

I know there are literally dozens of other factors that can affect how much pressure it takes to clear a screen, but my general principal always applies, print with just enough pressure to get the ink to clear the screen.  You can change numerous other factors to do that besides actual print pressure but it is a major component of the process. 

[Homer]

let's toss flood bar pressure into this equation. we have to double stroke most of the time to get the ink to clear the screen -white ink that is- . I have tried everything from mesh counts, eom, pressure, inks, bases, new platens, warm platens, swearing, speed, squeegies, angles, garments, off contact, list goes on -we just can't get it to clear right in one pass without really cranking the pressure. I am using the old school twist-n-lock pressure jammies. . .my next thing to play with is the flood pressure.

[Clark]

I flood heavier than most I would guess.  That said the only time my pressures get above 40 is printing poly ink.  When I got the press the previous owner had all of the pressured at 60+.  FOr most day to day stuff I find 30psi to be just about right.  However there are times when I can clear the mesh with so little pressure the choppers won't lift till the fill blade is half way through the screen, so the lowest we go is around 20.

That's weird Homer.  I can clear Wilflex Quick white or Rutland Snap White all day long at 30-35psi through a 166N with one stroke.  I probably couldnt do it with a standard 70 duro, but I run smilin jacks almost exclusively.

[ZooCity]

let's toss flood bar pressure into this equation. we have to double stroke most of the time to get the ink to clear the screen -white ink that is- . I have tried everything from mesh counts, eom, pressure, inks, bases, new platens, warm platens, swearing, speed, squeegies, angles, garments, off contact, list goes on -we just can't get it to clear right in one pass without really cranking the pressure. I am using the old school twist-n-lock pressure jammies. . .my next thing to play with is the flood pressure.

Again, I'm no auto op but that's what I see as the major factor in clearing the screen in a single stroke if the other major variables are dialed in - ink rheology, mesh, eom, tension, art, off contact, press is in parallel, blades are sharp and true, angles are correct, press is capable of repeatability, and of course assuming all of the previous is appropriate for the substrate.

I've noticed that when our ink is "rolling" on both the flood and print stroke that we get excellent clearance. Warm temps facilitate this for sure. I believe Joe Clark (?) refers to this as the ink "funnel" in some of the technical articles I've perused.  If I was in your shoes Homer, I would lock down every other variable, get it as close as possible and maybe try out a newman flood (not the squeegee, just the flood).  They seem to have really latched on to the concept of getting a good rheological response out of the ink on the initial fill stroke. 

[DouglasGrigar]

Contrary to some statements there is no one setting for pressure whether its PSI or old school twist and lock. This will depend on blade profile, durometer, unsupported height, angle of attack, and speed of travel. Then there is mesh count and tension, ink rheology, and off contact. There's probably more interdependant factors but that's enough variables to think about this early in the morning.
Seasoned press ops know how to "read the screen" in order to determine all this. Ideally when the stroke is completed you should be able wipe your finger across the image area and have it come off with practically no ink on it. If you are achieving proper shear and insufficient coverage you may wish to go back to the other variables and re-asses your pre-press. The quick bandaid is to double stroke.
tp

No newbie wants to hear the fact that in this issue we have at least... what... 20 variables to deal with, and then the problem of the “kiss the shirt with ink” thing that is only confusing to a newbie. Who wants to deal with the confusion with “kiss the shirt” could be (of course this changes with the variables) 25 pounds of pressure?