Auto press off contact

[chubsetc]

I am about 2 months into printing on my new diamondback, and am still having trouble clearing the screen with even 2 passes when printing directly onto the shirt (i've had some better luck while printing on an underbase but still need 2 strokes) I've tried different things with the squeegee/flood pressures, speed, and angles and modifying my inks.  I finally got down to platen level to look at the off contact (which is set at its smallest distance) and I feel like there is way too much off contact.  With the shirt on the platen I had room to set 2 quarters.  So my questions are:

1.  Is it possible that excessive off contact is causing my issues clearing the ink.

2.  How much off contact do you guys usually use on standard t's?

Also I am using roller frames with all my mesh tensions between high 20's and mid 30's.  I liked to run 160-180 mesh for my spot color white bases on t's with the manual press and can't even clear a 110 in 1 stroke on the auto.  I need to check every head as i just checked the off contact distance on 1 head but I am worried the press wasn't setup right. 

[alan802]

Yeah, can't clear a 110 with one stroke is definitely a problem.  Our OC on our high tension screens is roughly 1/16" and we can go lower than that to around .06-.08".  I think you'll be fine at about half the OC that you're using now, one quarter.  I also had a guy in a recent workshop that was somewhat experienced in automatic printing and was having issues with clearing the screen with one stroke, even through low mesh screens, same auto and specs.  I gave him a few pointers and I'll email him over the weekend to see what kind of progress he's had with single stroking versus double.

First thing I would do would be lower the central OC to around 1/16" for those high 20's screens.  Then I'd take a look at your squeegee angle and adjust those to about 75-80 degrees.  Then sharp squeegees of the right durometer, I recommend something around 70-75 duro.  If your press has squeegee regulators then drop them to about 30psi and depending on mesh count, go lower or higher.  Another area I would check is the actual mesh count.  Do you have a way to check to see if a 110 is actually a 110.  Then I'd check to see what thread thickness your mesh has.  % mesh open area makes such a huge difference in single versus double stroking and if I had an all air machine, I'd probably have nothing but thin thread mesh with larger % open area.

And the sad part about most of what I just said is that it means very little if your press wasn't setup correctly and calibrated to a fairly high tolerance.  If your screen in print head 1 is at 1/16" OC and the screen on head 6 is 1/8", then you've got problems that can only be fixed by paralleling the press.

[Screened Gear]

I do almost zero offcontact to about 1/8. I run statics

I think the best way to help is to see a video of the press printing. Show all the settings and angles se we can see every thing. Many times what is wrong is not what you think it is. More off contact usually helps clear the screen. Let's see a video.

[inkstain]

I am about 2 months into printing on my new diamondback, and am still having trouble clearing the screen with even 2 passes when printing directly onto the shirt (i've had some better luck while printing on an underbase but still need 2 strokes) I've tried different things with the squeegee/flood pressures, speed, and angles and modifying my inks.  I finally got down to platen level to look at the off contact (which is set at its smallest distance) and I feel like there is way too much off contact.  With the shirt on the platen I had room to set 2 quarters.  So my questions are:

1.  Is it possible that excessive off contact is causing my issues clearing the ink.

2.  How much off contact do you guys usually use on standard t's?

Also I am using roller frames with all my mesh tensions between high 20's and mid 30's.  I liked to run 160-180 mesh for my spot color white bases on t's with the manual press and can't even clear a 110 in 1 stroke on the auto.  I need to check every head as i just checked the off contact distance on 1 head but I am worried the press wasn't setup right.

Howdy.
Hope to help in some way.
I've had my diamondback for about 3 months or so and am very pleased!  In the beginning I was having some issues like yourself.  The good guys here helped me a lot with how to improve my printing, cause to me it's pretty different then the manual printing that I did for many years.
First, Sam from Palomar asked me how I coat my screens.  I would coat them 1/1 with the sharp edge.  I was told by him to coat them 2/2 with the round edge.  It sorta scared me, thinking my exposures wouldn't work as I use flourescent bulbs.  But I tried it, and my screens exposed great, maybe had to add a little more exposure time.  It made the HUGEST difference in printing for me.  So first, try coating your screens 2/2 with the round edge.

I use newman rollers as well.  Got some 150s mesh, 160 mesh, 200, etc.  I coat them all the same way except my 300's.
My off contact on my press is set to the lowest setting, never measured it, but it's pretty close to my shirts when printing.
I use around 30-35 pressure on my 150s meshes, 40-45 on the other meshes, depending on the ink.
Underbases I almost always to a double stroke.  Top colors you I can get away with one stroke depending on the design.
Squeegee angle is about 15 degrees.  Slower stroke on bigger designs.

Hope this helps in some way and if you have any other questions, I can try and help.
Cheers!

[Socalfmf]

Chubs..

there is a laundry list of things I would check...

#1.  like ink stated...how are you coating your screens?
#2.  what is your flood pressure?  it should have a little pressure to get the ink into the stencil
#3.  what are all your settings? pressure, angle ect.
#4.  how fast is your flood...is this happening with all colors or just say white ink or gold?
#5.  which notch is your central off contact?


having some of those questions answered could help a lot...also if you have an Iphone we can facetime and show you our entire press set up.  we will hit the million mark on our press this year...pretty cool....

let me know or pm me...but those questions should help us help you

sam

[chubsetc]

Hey guys, thanks for the reply's.  My wife just had a little girl on Wednesday so it may take me a bit to get some pics/video.  I have searched the boards and watched other conversations to try to get this figured out on my own over the past 2 months but I don't want to keep hitting things 3 times and just use excessive strokes as a crutch.  I also want to start pulling off discharge underbases but If I can't lay atleast a nice 230 on top with plastisol I feel like its kind of worthless.

To answer a couple of the questions, as for the emulsion:

I use the AWT coater with only one edge, coat my 110's and 160's with either 3/2 or 4/1 and my other meshes I usually coat 2/2.

Right now im using Aquasol HVP, and I'm using Sefar E-mesh.  Hoping to connect with a supplier close to me to get some S-mesh in.

I have my floods set so that they are just short of touching the mesh.

I have only had good luck using about 50 psi on the print stroke, my angle is usually 15 degrees.

My only squeegees right now are 70 durometer.  I ordered some 70/90/70 but don't have it yet.

Sam- my off contact is on the first setting which was set to be the thickness of 1 quarter by the installer but it seems like it changed since the install.  I was only using head 8 for a 1 color when I noticed what I thought to be excessive off-contact even at the smallest setting.  I will recheck all my heads next time I can get to the shop.  Tony from M&R was here for a couple days helping me out after the install and he said that the diamondback is typically installed with the 1 quarter width of off contact but it is on the second notch so you can get closer to the screen when on the first notch.  I do have an iphone so a facetime session would be great.

Thanks again for any help in advance.

Eric

[Rockers]

What helped us a lot was adding some reducer to the white, having the floodbars actually touch the mesh so that you fill the stencil and depending on the image size increase the speed f your print stroke.
Make sure you have enough glue on your pallets. We apply an angle of 15 degrees. 65/90/65 squeegees even though I would like to try a 75/90/75 soon. Off contact is around 2mm or 5/64 of an inch, that's our lowest setting. We use only roller frames with tension of 35-40N.

[ScreenPrinter123]

In addition to what everyone else has said, could you go a little lower on where you shoot out the image?  The tension at 5" from outer diameter and could be quite tighter and therefore needing a butt load more pressure to clear than, for instance 6.5-7" from od. If the entire image isn't clearing I'd say this prolly isn't  the issue, but if its a wide image and its only at the top or the very edges that clearing issues are occurring I'd try lowering the image or using wider screens as a possible help too.  Just a thought.

[Dottonedan]

I'd imagine that everything everyone said is correct and valid. I'm adding a theory that isn't mentioned yet. It could be nothing, but could also play a roll.


You mentioned coating 3&2 and 4&1.  To me on low mesh like that it sounds right. But if you are traveling slow on that 3&2 for each pass, you could be lawing down too thick of an emulsion layer causing a very long tube or (image area opening). Lets say they are halftones,  See image below.


Long tubes of emulsion can bee "too long" for the ratio of pressure and ink thickness to pass all way way though. It could be getting hung up in the stencil and thus not clearing the screen.


I'm not saying this is your answer. Just another thought to look into.

[ScreenFoo]

Lots of good stuff.  If you're printing detail and/or dots, Dan is right on the money.  Say a 110 with an 80 micron thread is about 144 microns thick, 3/2 coating could be 50+% EOM.
Rule of thumb I've always heard is the dot shouldn't be any smaller than the thickness of your stencil, 288 microns is a pretty big minimum dot size.
I know from messing it up myself that a 125/72 coated 2/1 or even 1/1 will print a properly ranged 25-35LPI halftone much better than one coated 2/2.

I think Rockers touched on what I'd look at first--reducer isn't the sin many will present it as.
As far as getting more ink down in one stroke, it's definitely a contested opinion, but I also have great luck with thicker inks pushing the floodbar into the mesh at least slightly. 
Make sure it's not so far down that bumping the platens up will split your screen against it.

[Rockers]

If the white is too thick you can as well add viscosity buster. I saw the girls at Wilflex recommending that on the M&R forum. But be careful, it does not cure and therefor has to be used as instructed, I think only 2-3% max.

[ondalevel]

when you speak of coating the screens 2/1 or 3/2 which side is getting the first number, the print side or the shirt side? or does it matter

[Inkworks]

ondalevel, check this article on coating:

http://www.theshirtboard.com/index.php/topic,2621.0.html

[Lizard]

1.  This may help a little.  We coat 80 mesh, 1-1, 110 mesh, 2-1, every thing else 3-2.
2.  This will help a lot.  Flood hard enough that you can see the image in the screen after the flood stroke.  Then you will need minimal pressure to clear the screen.  White underbase will sometimes need 2 strokes depending on mesh.
3.  Top colors should never need 2 strokes.  Again flood hard, print light.

[Frog]

when you speak of coating the screens 2/1 or 3/2 which side is getting the first number, the print side or the shirt side? or does it matter

Always end with the squeegee side. That pushes the emulsion through to the shirt side where it does its thing. Remember that your emulsion works as both an ink-holder (from the flood or fill stroke) and a gasket on the print stroke.