# DIY 100 UV LED Exposure Unit.



## MBrhythm (Mar 1, 2007)

I'm going to build my own LED exposure unit. 

What I have:
120 3w UV LEDs 395-410nm 

Glass top 40" x 30"

Vacuum top to fit. 

I need help with power supply and driver. 
Can anyone point me to the right kind of driver/power supply unit i need? 

I'll keep everyone posted once I start building.


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## sben763 (May 17, 2009)

You need more info before deciding on a driver. Forward voltage. Your best bet would be several drivers if your in the standard 3v range of most 3watt, what angle are they. If they are 60- 120 degree your wasting your time. There will be too much overlapping and undercutting will occur and will likely be worse then a unfiltered black light unit. 15-45 degree depending on your distance is what you'll need. 

You can pick up 18 Led 3 watt drivers for around $9. I run 4 on my multi led conversions.


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## MBrhythm (Mar 1, 2007)

sben763 said:


> You need more info before deciding on a driver. Forward voltage. Your best bet would be several drivers if your in the standard 3v range of most 3watt, what angle are they. If they are 60- 120 degree your wasting your time. There will be too much overlapping and undercutting will occur and will likely be worse then a unfiltered black light unit. 15-45 degree depending on your distance is what you'll need.
> 
> You can pick up 18 Led 3 watt drivers for around $9. I run 4 on my multi led conversions.


Where did you find 18 LEDs for $9?


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## sben763 (May 17, 2009)

Driver for 18-3W LEDs $9.


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## MBrhythm (Mar 1, 2007)

sben763 said:


> Driver for 18-3W LEDs $9.


Sorry. Read that wrong above. 

Still looking to build my own.


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## elusiveprint (Aug 29, 2013)

sben763 said:


> You need more info before deciding on a driver. Forward voltage. Your best bet would be several drivers if your in the standard 3v range of most 3watt, what angle are they. If they are 60- 120 degree your wasting your time. There will be too much overlapping and undercutting will occur and will likely be worse then a unfiltered black light unit. 15-45 degree depending on your distance is what you'll need.
> 
> You can pick up 18 Led 3 watt drivers for around $9. I run 4 on my multi led conversions.


Sben, how close to the glass can you go with LEDs do you think? Is 2" too close if you are using the right degree LEDs? At that distance would 15-45 degree still be the ideal range?

Thanks


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## sben763 (May 17, 2009)

It all depends on the setup. If using multi point they can be relatively close. I am using a single point 200w at about 12-14". With the muti point at you would have to figure lens degree, led spacing to prevent over lap before calculating the space to glass.


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## elusiveprint (Aug 29, 2013)

sben763 said:


> It all depends on the setup. If using multi point they can be relatively close. I am using a single point 200w at about 12-14". With the muti point at you would have to figure lens degree, led spacing to prevent over lap before calculating the space to glass.


Makes sense. I working on a table top unit that uses 2 bare frames stacked on top of each other as the box. By my calculations the bottom of the glass will be 2.75" from the LEDs not including the height of the LEDs (however small that would be). The strips I have seen posted before had 1" spacing. Based on my research of the better commercial units out there, the LEDs create a grid meaning the strips are set 1" apart so that all it creates "squares". Know what I mean? Do you think doing a unit in this manner would produce good results? If I spaced the LEDs as such, what do think the lens degree would have to be to minimize any undercutting that would occur? 

Im very into building a tabletop LED unit as I had great success with my last homemade unit. UV setup, dual cure emulsion holding 65lpi on 255 mesh with a 4-5 minute burn time. I was hoping to improve the burn time with the LED unit and also hold some finer detail. Do you think its possible with the route I'm headed?


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## elusiveprint (Aug 29, 2013)

sben763 said:


> It all depends on the setup. If using multi point they can be relatively close. I am using a single point 200w at about 12-14". With the muti point at you would have to figure lens degree, led spacing to prevent over lap before calculating the space to glass.


Also, by my calculations I would have anywhere from 500-600 LEDs in the unit depending on how much space I leave inside the unit for safe lights If I space them the way I described in my last post. These are the strips I saw posted before somewhere: 16.4ft 5M UV Ultraviolet 395nm 5050 SMD Purple 300 LED Flex Strip Light 12V free shipping-in LED Strips from Lights & Lighting on Aliexpress.com | Alibaba Group

How many watts is each bulb putting out? Do you know of anywhere to get better LEDs? Are these any good?

Thanks for your help.


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## sben763 (May 17, 2009)

With what you are wanting to do you won't get much better results then your black light unit. The LED multipoint require that it be engineered so that the light not over lap or even over lap or uneven exposure will occur. Your link to the LEDs is what the origonal patent is based upon although if I remember right the original was 1w SMD strips. Most those strips are 1/8-1/4 watt so a lot would be needed. Then it was refined by others with stronger LEDs, engineered overlap or exact line up of the light. I gave it several tries with multipoint led and you can get good results. I'm sure if I took the time to figure a exact overlap or butt the light edges it would be close to the single point I'm using now. It was just much easier. I used 3w LEDs for the multipoint. 72 of them for a 23x31 area. 4 LED drivers each hooked to 18 in series. That set up cost around $150 plus you have to solder all the connections. I probably have 72 new 3w 385nm and drivers left over from my experimentations.


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## elusiveprint (Aug 29, 2013)

sben763 said:


> With what you are wanting to do you won't get much better results then your black light unit. The LED multipoint require that it be engineered so that the light not over lap or even over lap or uneven exposure will occur. Your link to the LEDs is what the origonal patent is based upon although if I remember right the original was 1w SMD strips. Most those strips are 1/8-1/4 watt so a lot would be needed. Then it was refined by others with stronger LEDs, engineered overlap or exact line up of the light. I gave it several tries with multipoint led and you can get good results. I'm sure if I took the time to figure a exact overlap or butt the light edges it would be close to the single point I'm using now. It was just much easier. I used 3w LEDs for the multipoint. 72 of them for a 23x31 area. 4 LED drivers each hooked to 18 in series. That set up cost around $150 plus you have to solder all the connections. I probably have 72 new 3w 385nm and drivers left over from my experimentations.


What kind of results did you get with your multipoint? How far apart were the LEDs? I would open to changing up the spacing of the bulbs or whatever is needed to make it work. I heard 385 is good for Photopolymer emulsions but diazo requires a hiher nm.. is that true?


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## elusiveprint (Aug 29, 2013)

sben763 said:


> With what you are wanting to do you won't get much better results then your black light unit. The LED multipoint require that it be engineered so that the light not over lap or even over lap or uneven exposure will occur. Your link to the LEDs is what the origonal patent is based upon although if I remember right the original was 1w SMD strips. Most those strips are 1/8-1/4 watt so a lot would be needed. Then it was refined by others with stronger LEDs, engineered overlap or exact line up of the light. I gave it several tries with multipoint led and you can get good results. I'm sure if I took the time to figure a exact overlap or butt the light edges it would be close to the single point I'm using now. It was just much easier. I used 3w LEDs for the multipoint. 72 of them for a 23x31 area. 4 LED drivers each hooked to 18 in series. That set up cost around $150 plus you have to solder all the connections. I probably have 72 new 3w 385nm and drivers left over from my experimentations.


Kind of curious how M&R is doing it. I saw your post about forward facing LEDs so the beams go straight up. Can those types of bulbs be sourced?


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## sben763 (May 17, 2009)

Every manufacture is diffrent. A few years back 365nm-385nm was considered optimal spectrum for photopolymer emulsions. 395-410nm for diazo(dual cure). With advancement and diffrent sensitzers as well as mixtures of sensitzers the spectrums of emulsions today vary, Saati PHU photopolymer spectrum is 405nm. Dual cure is a reduced photopolymer and then diazo is added by the end user. With the changes in the photopolymers it also will effect the dual cure depending on the sensitzers used by the manufacture. 

My testing I was able to use 385nm as a all around spectrum for multiple emulsions. What I have always advised if thinking of going to a DIY LED is to pick emulsion, stick with it and build the unit with the peak spectrum the manufacture arises as the peak since the spectrum is narrow with LED compared to other light sources.


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## elusiveprint (Aug 29, 2013)

sben763 said:


> Every manufacture is diffrent. A few years back 365nm-385nm was considered optimal spectrum for photopolymer emulsions. 395-410nm for diazo(dual cure). With advancement and diffrent sensitzers as well as mixtures of sensitzers the spectrums of emulsions today vary, Saati PHU photopolymer spectrum is 405nm. Dual cure is a reduced photopolymer and then diazo is added by the end user. With the changes in the photopolymers it also will effect the dual cure depending on the sensitzers used by the manufacture.
> 
> My testing I was able to use 385nm as a all around spectrum for multiple emulsions. What I have always advised if thinking of going to a DIY LED is to pick emulsion, stick with it and build the unit with the peak spectrum the manufacture arises as the peak since the spectrum is narrow with LED compared to other light sources.


This is the only emulsion I use: CCI WBP Hybrid Emulsion - 5 Gallon | ScreenPrinting.com by Ryonet 

Any idea what the peak spectrum is? I searched around a bit and couldnt get the answer. 

Also, I'm no engineer but I'm thinking if the LEDs were placed in 1" squares and had a 45 degree angle, wouldn't that make the glass 2" above the LEDs to create a butt registration of the light beams? And that would make 1" above the glass 100% overlap?


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## sben763 (May 17, 2009)

You should be able to email CCI to get the peak spectrum. I highly doubt the clowns at Ryonet would know. 

As for the lens degree vs distance there is a way calculate the beam spread. I just turned on a led, used a black cardboard to measure approximate beam spread. I ended up going to a single source LED to eliminate all the variables.


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## charvy (Jun 4, 2014)

Hi, I'm not new in screen printing world, but trying to learn from you. i've seen advances made in led exposure unit by SEAN. now, i'm trying to find the right led for this purpose. 

now, thanks to SEAN, i know 385nm is good option for most emultions. (you used 100w, 3A, 120ºVA)

may i use 365nm 50W?

thank you so much;

I'm expecting to have enough space to show you my set up. (I'm now in a 3m x 3m room)


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## macman29681 (May 24, 2013)

sben763 said:


> You should be able to email CCI to get the peak spectrum. I highly doubt the clowns at Ryonet would know.
> 
> As for the lens degree vs distance there is a way calculate the beam spread. I just turned on a led, used a black cardboard to measure approximate beam spread. I ended up going to a single source LED to eliminate all the variables.


Where can I get a single source LED that has the right spectrum for screen printing?


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