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screen printing => Screen Making => Topic started by: TCT on October 31, 2015, 10:20:27 PM
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Thought this question was covered before but couldn't find it anywhere...
For CTS users that don't have a integrated exposure device- When you made the switch from films and glass exposure unit to CTS and no glass, how did you determine your new exposure times/units? I don't seem to remember hearing(not that it hasn't been talked about) about a exposure test or a step test you can print on your screens. Just trial and error?
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Start with 50% of what you were doing if you glass was 3/8 thick
Sent from my iPhone using Tapatalk
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Start with 50% of what you were doing if you glass was 3/8 thick
Sent from my iPhone using Tapatalk
Johnny on the spot there Alex! Don't think I barely finished pushing "post"! ;D Let me guess, your kids are just done trick or treating now also?
Good starting point, thanks!
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Tape a stouffer strip to the screen before exposjng.
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All the above and lots of trial and error, I have the 1st starlight with the CTS conversion no glass, so I have probably been doing it the longest. Still testing as matter of fact!
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We still use glass on our starlight, we have a constant loop basically 2 guys, one outputting screens / exposing. The other taking the exposed screen and washing it out. I assume removing glass would speed up burning but not much point as it takes about the amount of time to burn it as it dose to rise.
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We still use glass on our starlight, we have a constant loop basically 2 guys, one outputting screens / exposing. The other taking the exposed screen and washing it out. I assume removing glass would speed up burning but not much point as it takes about the amount of time to burn it as it dose to rise.
are you just 'shimming' the screen above the glass?
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Trial and Error.
Taped a calcluator to it and exposed, then went from there. We are still tweaking, but that's due to no automatic coater yet.
After a 4-5minute soak in water, screens should rinse out very easy in 30 seconds or less...if you loose dots quickly add half a sec and repeat.
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We still use glass on our starlight, we have a constant loop basically 2 guys, one outputting screens / exposing. The other taking the exposed screen and washing it out. I assume removing glass would speed up burning but not much point as it takes about the amount of time to burn it as it dose to rise.
are you just 'shimming' the screen above the glass?
Correct.
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I may have to give 'shimming' a try... might help with the over-cure on one side, raw on the other side, as the screen will expose slower....
hmm...
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I may have to give 'shimming' a try... might help with the over-cure on one side, raw on the other side, as the screen will expose slower....
hmm...
We use paint sticks, so not super thick. We have zero issues.
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we shoot through the glass as well. it gives us a bit larger window to nail times....and the metal fab guy never got me a quote back. It's a small job for him anyway.
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I may have to give 'shimming' a try... might help with the over-cure on one side, raw on the other side, as the screen will expose slower....
hmm...
We use paint sticks, so not super thick. We have zero issues.
we do something similar on our Douthitt DMZ - we went with yardsticks. zero issues as well
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yesterday, I tried shimming the screens about 1/8" 'higher' than the glass would have been (but left the glass out as I have my homemade cts conversion kit on my starlight)
interestingly enough, the times changed a touch, but more importantly, the stouffer strip results and resulting screens seem better... I need a few days of HSA and discharge jobs before I'll be willing to say that my old problems are licked, but I'm guessing that I was a fraction of an inch too close to the LEDs.
I cut up some various sets of blocks in 1/16" increments so I can play with the screen height a bit more... I'm shooting a halftone grid on the edge of the screens where I can, and I haven't noticed any differences in the halftones when looking with a loupe.
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This shimming idea is pretty fascinating to me. But couldn't this potentially result in hot-spots, cold-spots and potentially undercutting from the change in what I'm sure was a carefully engineered distance/angles to account for the extremely multi-point nature of LED exposure units?
I'm curious if Rich has anything to chime in with.
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yesterday, I tried shimming the screens about 1/8" 'higher' than the glass would have been (but left the glass out as I have my homemade cts conversion kit on my starlight)
interestingly enough, the times changed a touch, but more importantly, the stouffer strip results and resulting screens seem better... I need a few days of HSA and discharge jobs before I'll be willing to say that my old problems are licked, but I'm guessing that I was a fraction of an inch too close to the LEDs.
I cut up some various sets of blocks in 1/16" increments so I can play with the screen height a bit more... I'm shooting a halftone grid on the edge of the screens where I can, and I haven't noticed any differences in the halftones when looking with a loupe.
I can assure you the placement of the LED grid is correct where it's at. Many hours of engineering went in the placement. By shimming the glass and raising the height of the screen it will still work but slower. We make a conversion rack to eliminate the glass and it places the screen exactly where it belongs from the grid. Just a FYI.
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I can assure you the placement of the LED grid is correct where it's at. Many hours of engineering went in the placement. By shimming the glass and raising the height of the screen it will still work but slower. We make a conversion rack to eliminate the glass and it places the screen exactly where it belongs from the grid. Just a FYI.
it's on my list of things to purchase...
However... I'm still wondering tho on the 'slower' is better... it just seems like the people who are posting the best results with WB work are the ones that are still using glass in their units... which of course slows down the exposure, which in turn gives more chance of curing all the way through the stencil.
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I can assure you the placement of the LED grid is correct where it's at. Many hours of engineering went in the placement. By shimming the glass and raising the height of the screen it will still work but slower. We make a conversion rack to eliminate the glass and it places the screen exactly where it belongs from the grid. Just a FYI.
it's on my list of things to purchase...
However... I'm still wondering tho on the 'slower' is better... it just seems like the people who are posting the best results with WB work are the ones that are still using glass in their units... which of course slows down the exposure, which in turn gives more chance of curing all the way through the stencil.
Reading this was kind of funny in a way, most of you bought the LED units for it's speed of exposing screens I think at least that was what it seemed like when you all first started buying this unit, now slower is better? might as well have kept what you had or have unless the electric savings over time is a big factor.
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I can assure you the placement of the LED grid is correct where it's at. Many hours of engineering went in the placement. By shimming the glass and raising the height of the screen it will still work but slower. We make a conversion rack to eliminate the glass and it places the screen exactly where it belongs from the grid. Just a FYI.
it's on my list of things to purchase...
However... I'm still wondering tho on the 'slower' is better... it just seems like the people who are posting the best results with WB work are the ones that are still using glass in their units... which of course slows down the exposure, which in turn gives more chance of curing all the way through the stencil.
there is a lot of misinformation posted on this subject. Slower is not better.
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I can assure you the placement of the LED grid is correct where it's at. Many hours of engineering went in the placement. By shimming the glass and raising the height of the screen it will still work but slower. We make a conversion rack to eliminate the glass and it places the screen exactly where it belongs from the grid. Just a FYI.
it's on my list of things to purchase...
However... I'm still wondering tho on the 'slower' is better... it just seems like the people who are posting the best results with WB work are the ones that are still using glass in their units... which of course slows down the exposure, which in turn gives more chance of curing all the way through the stencil.
Reading this was kind of funny in a way, most of you bought the LED units for it's speed of exposing screens I think at least that was what it seemed like when you all first started buying this unit, now slower is better? might as well have kept what you had or have unless the electric savings over time is a big factor.
Yeah but Darryl, I think what they are talking about is in seconds. Unlike the MH units like I still use, chunks of minutes to dual cures and diazos. But like Diggler and his starlight. He's talking about like SBQ emulsions in 1.5 seconds for perfect crosslink, and then 30 seconds, to maybe a minute for a dual cure, which there aren't many MH units out there that can do that. I used to have a Richmond Solar Beam 10k. Used it with glass and film, still needed what translated to a good 8 minute exposure for an emulsion like HXT, or Ulano 925wr, or Nova with diazo. When we went CTS that same unit only shaved off a couple of those minutes. Now using a Trilight, my HXT exposures range from 4-6, sometimes 7 minutes depending on mesh counts. If our water based orders really increased I would need to speed things up. So even if the starlight needs 1-2 minutes for a perfectly crosslinked Dual cure or diazo emulsion for discharge printing. That's still faster than any MH unit I've heard about and I don't think there is much stronger out there than the Trilight or Solar Beam for MH units. I would love to put one in now, but with the slower time of year approaching, the huge investment we just installed here and of course some added expenses we didn't plan for, I gotta wait a little bit, but I see a starlight in the near future. Spending some days with PattFinn from M&R for the training on the new GT3, his experiences working in the screen printing development department at M&R, we got to learn a ton about emulsions, what types are best suited for what mesh you are using and the type of printing you are wanting to do. Trust me, he's a waterbased guy, even though that department does tons of plastisol, the WB is where Patrick excels at so he got to be right there with the testing of emulsions and prints and whats going to work and not work. I've learned that cheaping out only hurts all of us. So if you buy a starlight and plan to use it with a CTS, that little bit extra for the rack that was engineered specifically for that purpose is a minor investment vs the time and waste of dicking around with a home made rig. I've wasted too much time and money trying to rig things. Either do it right or wait a little bit till you can. At the very least, just know that your expectations most likely will not be met trying to rig something and not blame the gear for it's performance when a work around device is jimmy'd into place. I have to say, 1.5 seconds per screen for SBQ emulsions is pretty sick. I could image a stack of 50 screens, return and email or two and have a highschool intern place the screen, push the button, and repeat. All I'd need after that is one of those cool Eco Rinse deals. Same highschooler could do that. I bet 50 screens in that loop would be done verrrrrrrry fast.
Kinda went off topic there, lol. Must have inhaled too much discharge stank today. lol :o :o :o ;D ;D ;D