Single point LED....

[TCT]

Had a demo of the single unit last week and for the money looks like great results in our CTS shop.


I think we will be going forward with the triple soon, although the concept of no integrator is a bit counter to my upbringing.


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Greg, are you guys planning on using the 300 unit for exposing your "wall of screens" once they are imaged?

[GKitson]

That's the initial plan, we were exposing to 9 on the 21 step scale at 30 inches and 30 seconds with the single.


Will do more eval with the triple as we move forward


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[ABuffington]

Hello TCT and all the members.

Regarding water base, discharge and HSA screen exposure.  I get to see a lot of printers using these new HSA inks with long print runs and typically those that have high wattage units tend be able to avoid break down more than low wattage units or direct light to screen exposure units.  The other key area is the right emulsion for the ink.  In terms of the ink's ability to break down the emulsion I look at them like this:

Plastisol - not aggressive at all.
Water base (totally transparent no opacity inks) - Aggressive rating 2 on a 1-5 scale
Discharge - Aggressive rating 4
HSA - Agressive rating 5 - but this can vary from different manufacturers

My thought is we need to look at an individual light ray from the various units and how much strength it has left when it hits the squeegee side of the emulsion.  This is the breakdown area usually not the print side.  So if you have a 1000 watt vs a 5,000 watt the 1,000 watt will be quite weak after going through the emulsion and mesh compared to the 5,000 watt which will have more punch after the mesh and emulsion it needs to travel through.  Give me the strongest light ray possible for Discharge and HSA inks. The more aggressive the ink, the more light energy I want to expose with.  Emulsion is not underexposed only, or over exposed only.  There is a linear ramp in between and some light sources give decent images and partial exposure.  For these inks I want both the best resolution and the best exposure, where Metal Halides are proven to do so.

LED's overcome this with proximity and have strength due to the inverse square law.  I did some math on another post here that shows that doubling the distance, multiplying the wattage by 4 at each doubling yields comparable wattage at the 40-48" distance for metal halides.

so Starlight wattage proximity is 3/4"x2=1.5" multiply by 4 for comparable wattage needed to equal the 3/4" distance exposure, 1.5x2=3" multiply previous wattage by 4, 3x2 = 6" multiply previous wattage equivalent, 6x2=12" multiply previous wattage, 12x2=24 multiply previous wattage, 24x2=48 multiply previous wattage.  This is the equivalent wattage needed to match the Starlight wattage at 3/4" 

So if the 300 watt is at 30" x2 = 60" 300 watts times 4 for the equivalent wattage needed at 60" which  is 1200 watts.  So replacing in a 1000 watt MH would work, but then also the histogram of the light spikes typically in an LED at one wavelength while the MH 1000 may have a multi spectral bulb that emulsions prefer.  Especially dual cures that have diazo (likes 360nm) and SBQ (likes 400-420).  So a single spectral bulb even with equivalent exposure may not yield as strong a screen for wb, discharge and especially HSA that a multi spectral with equivalent wattage might yield.  It's the quality of the cross linked molecules and what we call handshakes.  The stronger the handshake brought about by the sensitizers and what percentage of emulsion molecules have complete handshakes will determine the emulsion strength.  Stronger light equals molecule handshakes that forms a stronger exposed screen.

My tests on the starlight were very strong.  The scattered light doesn't seem to matter much, but could be noticeable on 65-85 lpi tonals with inkjet imagery, wax, no problems.

I am old school.  I like Metal Halides and probably I am little biased.  But nothing has ever come close to exposing as well as my 8k Olec (Douthitt now markets them)  for long discharge runs.  We printed for Disney back in the day and had one set of screens with Aquasol TS and A&B hardened last to 250,000 pcs on an 8 color discharge and foil print.  Once your exposure unit does that for you and you see the results in non stop production, there is no reason to go a different direction.  For shorter runs and especially plastisol the new LED's are so much cheaper to operate that it is obviously a benefit. SBQ can be post exposed to gain more strength as well as hardening screens, but these are band aids that can't equal the initial exposure with strong light at the longest time possible without over exposing. 

[TCT]

Hello TCT and all the members.

Regarding water base, discharge and HSA screen exposure.  I get to see a lot of printers using these new HSA inks with long print runs and typically those that have high wattage units tend be able to avoid break down more than low wattage units or direct light to screen exposure units.  The other key area is the right emulsion for the ink.  In terms of the ink's ability to break down the emulsion I look at them like this:

Plastisol - not aggressive at all.
Water base (totally transparent no opacity inks) - Aggressive rating 2 on a 1-5 scale
Discharge - Aggressive rating 4
HSA - Agressive rating 5 - but this can vary from different manufacturers

My thought is we need to look at an individual light ray from the various units and how much strength it has left when it hits the squeegee side of the emulsion.  This is the breakdown area usually not the print side.  So if you have a 1000 watt vs a 5,000 watt the 1,000 watt will be quite weak after going through the emulsion and mesh compared to the 5,000 watt which will have more punch after the mesh and emulsion it needs to travel through.  Give me the strongest light ray possible for Discharge and HSA inks. The more aggressive the ink, the more light energy I want to expose with.  Emulsion is not underexposed only, or over exposed only.  There is a linear ramp in between and some light sources give decent images and partial exposure.  For these inks I want both the best resolution and the best exposure, where Metal Halides are proven to do so.

LED's overcome this with proximity and have strength due to the inverse square law.  I did some math on another post here that shows that doubling the distance, multiplying the wattage by 4 at each doubling yields comparable wattage at the 40-48" distance for metal halides.

so Starlight wattage proximity is 3/4"x2=1.5" multiply by 4 for comparable wattage needed to equal the 3/4" distance exposure, 1.5x2=3" multiply previous wattage by 4, 3x2 = 6" multiply previous wattage equivalent, 6x2=12" multiply previous wattage, 12x2=24 multiply previous wattage, 24x2=48 multiply previous wattage.  This is the equivalent wattage needed to match the Starlight wattage at 3/4" 

So if the 300 watt is at 30" x2 = 60" 300 watts times 4 for the equivalent wattage needed at 60" which  is 1200 watts.  So replacing in a 1000 watt MH would work, but then also the histogram of the light spikes typically in an LED at one wavelength while the MH 1000 may have a multi spectral bulb that emulsions prefer.  Especially dual cures that have diazo (likes 360nm) and SBQ (likes 400-420).  So a single spectral bulb even with equivalent exposure may not yield as strong a screen for wb, discharge and especially HSA that a multi spectral with equivalent wattage might yield.  It's the quality of the cross linked molecules and what we call handshakes.  The stronger the handshake brought about by the sensitizers and what percentage of emulsion molecules have complete handshakes will determine the emulsion strength.  Stronger light equals molecule handshakes that forms a stronger exposed screen.

My tests on the starlight were very strong.  The scattered light doesn't seem to matter much, but could be noticeable on 65-85 lpi tonals with inkjet imagery, wax, no problems.

I am old school.  I like Metal Halides and probably I am little biased.  But nothing has ever come close to exposing as well as my 8k Olec (Douthitt now markets them)  for long discharge runs.  We printed for Disney back in the day and had one set of screens with Aquasol TS and A&B hardened last to 250,000 pcs on an 8 color discharge and foil print.  Once your exposure unit does that for you and you see the results in non stop production, there is no reason to go a different direction.  For shorter runs and especially plastisol the new LED's are so much cheaper to operate that it is obviously a benefit. SBQ can be post exposed to gain more strength as well as hardening screens, but these are band aids that can't equal the initial exposure with strong light at the longest time possible without over exposing.

[Sbrem]

I'm really liking this thread, a lot like a roller coaster; good solid information that can be used to make a decision depending on the size of your shop and length of runs. I've always had 3k to 5k MH, except for the arc lamp, but really like the idea of lower electricity costs of LED; the proximity seems to solve the depth of the initial exposure, at least for those of us printing 1K to 5K, not 250K. I'm sure orders that large take care of electricity costs better. We're about to see a 30% to 35% increase in electricity here in Massachusetts, OUCH

Steve

[blue moon]

So if the 300 watt is at 30" x2 = 60" 300 watts times 4 for the equivalent wattage needed at 60" which  is 1200 watts.  So replacing in a 1000 watt MH would work, but then also the histogram of the light spikes typically in an LED at one wavelength while the MH 1000 may have a multi spectral bulb that emulsions prefer.  Especially dual cures that have diazo (likes 360nm) and SBQ (likes 400-420).

isn't this the other way around? I thought diazo was around 400 and SBQ is at 360. . . not that it makes any difference in the argument.

pierre

[ScreenFoo]

^^I recall 370, but either way, pretty sure Diazo is lower than SBQ in wavelength.

edit:  Pretty sure I recalled wrong, that's what I get for never using SBQ. 


Alan:  Great read.

A single point LED could be the future, but from what I see of the industry (LED, that is,) it will likely be prohibitively expensive for a long time.
Would likely have a pretty esoteric heat sinking setup, unless there's some huge advance in LED tech.

I'm not selling my MH units anytime soon... 

[TCT]

A single point LED could be the future, but from what I see of the industry (LED, that is,) it will likely be prohibitively expensive for a long time.

With these single point units it doesn't seem that way.... The "list" prices were about $500 for the 100 watt unit and $1200 for the 300 watt unit. So take what you pay for a MH replacement bulb and the ROI on a single point unit(as long as it exposes as good or better) isn't that horrible...



I talked to 3 shops that have the units last week. It kind of sucks because they were shops/numbers that Saati gave me to call so that screws up the "honest review" aspect of things, but they all really liked the units. 2 of the shops had the 100 unit and 1 shop had the 300 unit. All were CTS and 2 of them were exposing multiple screens on a wall. All the shops were also using Saati emulsion.

It still leaves a lot up in the air for me here as I am still using films and have no intention switching from Murakami emulsion(Saati is sending over a sample gallon so we will see I guess).  For me 11 second exposure times are not something I would pay more for right now. If I could get them to ~45 sec. or less that would be huge. Even at that rate screens would be done exposing before the first one was washed out... It would remove the bottleneck we currently have at the exposure unit.

[ScreenFoo]

If there is an LED system that actually competes, single point, no undercutting, with a 5K or 8K MH unit I'd be interested in checking it out.  I'm assuming a sales person would have already bothered me if that were claimed, much less happening in reality.

The other thing about the market the way it is, you can get a MH for 500-1000, or even free, depending on the situation.   If you do any type of volume, it's easy to justify 300 bucks a year on a new bulb, when you never have to re-shoot a screen or lose a dot because of it.

As has been mentioned, it would likely have to be a VERY high wattage LED array, considering efficiencies are similar. 
Don't take me as being too retro-grouchy, I think it's cool. 

To me, it's not cutting edge, it's bleeding edge. 

[244]

If there is an LED system that actually competes, single point, no undercutting, with a 5K or 8K MH unit I'd be interested in checking it out.  I'm assuming a sales person would have already bothered me if that were claimed, much less happening in reality.

The other thing about the market the way it is, you can get a MH for 500-1000, or even free, depending on the situation.   If you do any type of volume, it's easy to justify 300 bucks a year on a new bulb, when you never have to re-shoot a screen or lose a dot because of it.

As has been mentioned, it would likely have to be a VERY high wattage LED array, considering efficiencies are similar. 
Don't take me as being too retro-grouchy, I think it's cool. 

To me, it's not cutting edge, it's bleeding edge. 

the StarLight would very well against any exposure unit you put up against it. Regardless of whatever wattage you would like to compare it to.

[Northland]

Sorry gents....I haven't read this thread end-to-end, so this post may be a rehash of previous comments:
Here goes:
-- I've got an old Atlas exposure unit that started life as a 'beamed blacklight" fluorescent.
-- A couple years ago, I converted it to MH to get a more through exposure with thicker stencils.
-- I became intrigued with the LED concept and decided to attempt another conversion
-- I bought 25 meters of 5050 SMD strip lighting (that's 1500 individual LEDs) and a pair of 12 volt LED drivers
-- I attached the strips to a piece of plexi and mounted it 4" below the glass of the exposure unit.
-- I've always been a dual cure guy... but this light is pretty wavelength specific (about 395-405), so I have switched to a pure-photo emulsion (Chromablue). Chromaline has a new LED specific emulsion "ChromaLIME", I'd like to try that.
-- I haven't burned enough screens to really fully dial it in, but a 137S mesh (coated 1x2) is about a 40 second exposure.
-- The real attraction for me is getting rid of the warm-up time required by the MH
-- I've got about $200 into materials and the jury is still out... I may go back to MH and dual cure, if the halftone dots aren't what I'm used to.
-- mine is definitely a crude DIY project, but I can envision a savvy manufacturer selling a drop in conversion.

[3Deep]

North I've been saying that from the start, some company will make a drop in version of LED, sorry Rich, but whatever bulbs you are using someone else might get the same ones and do the drop in.  some people will still rather buy a new unit while some others might use there old box and convert it's, just a matter of time before some smart cookie does this, it just seems to simple not to do this I could be very wrong on the simple, but time will tell.

[Prosperi-Tees]

Vastex already has retro kits

[IntegrityShirts]

North I've been saying that from the start, some company will make a drop in version of LED, sorry Rich, but whatever bulbs you are using someone else might get the same ones and do the drop in.

If someone were to use the same LED's that Rich uses, a drop in board, all wired up with power supply and operating on at least 100% markup would have to sell for over $2k. Starlight LED's ain't cheap!

North, I pretty much did the same thing with similar results here:
http://www.theshirtboard.com/index.php/topic,12120.msg114469.html#msg114469

I am in the process of trying out some different LED's that are non-waterproof. Along with powering EACH ROW individually to avoid power loss through the tiny traces on these strips. Hopefully will get better results this go around. If I can't get times under my 5k Olec, then it's just not worth anything more than a backup in case the MH lamp goes out unexpectedly.

[ScreenFoo]

I am sure you are correct about that, Rich--I am looking forward to seeing one in service, I would guess you guys have put some work into the geometry of the light that is so critical to a good exposure.   I would make the uneducated guess that a Starlight and your equivalent MH unit go for similar prices for good reason.  (And that is a guess, I have no idea what your NuArc stuff is going for these days)

But your products not withstanding, really I was just mentioning it seems like a poor decision TO ME to pay more (or possibly a lot more) for a single point 300W LED than you can buy a used 5K MH unit for, 300 dollar bulbs or not.

Perhaps it does make sense, for someone else.