screen printing > DIY - From master engineered marvels to cobbled together jury-rigged or Jerry-built junk!

My LED Exposure Unit Build

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Jhtitan:
So I have been reading just about everything I can on here. The Wife and I just bought out everything we needed from a semi local shop going out of business. Only thing missing was the exposure unit as his was a loaner and had to go back to its owner, who was not interested in selling it.

Attached is a JPG of my current design. Glass bed is currently @ 43"x 30". Right now that is pretty much just to cut 30" off the end of a sheet of MDF for the bottom. I wanted it to be large enough to get 2 screens on it at once if the need arises. Not sure if that is necessary or not.

I have planned 20 UV LED strips at @39" long sitting 3" below the glass. I have read about calculating this distance but have so far found no equations or formulas. LED's have a 120° cone. I have it figured at 20M of LED Stips and I bought an extra 5M strip to make sure I have some to replace any that needed it.

I am planning on running the vacuum thru the metal frame like the one they had and a few others I have seen in pictures. Lots of drilling and some welding but nothing I can't handle. In this configuration the vac blanket gets attached to the top of the frame with a adhesive gasket seal around the the other side for the glass contact seal. I had played with the idea of building it into the box. You can see the hole in the rear corner of the box I had planned on attaching a shop vac to.

I have not started on a base design yet. I am torn between making it hinge on the wall so I can drop it out of the way when not in use or putting prepped screen storage under it. Close off and light seal 3 sides with the front being some sort of door or curtain to access ready to burn screens.

I am open to suggestions if anyone has any. I have parts on order so I am still about a week away from starting the build and I plan to order the glass last just in case there are any last minute design changes.

As far as control, I plan to use a PC power supply for the 12VDC and I have this controller ordered:
https://smile.amazon.com/gp/product/B07LBJ9PYJ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Guy we bought everything from did have some neoprene left from replacing the blanket in his loaner unit and he had bought enough to replace it again if he had needed to.

Once I have it built and tested I could offer up some plans for this. Would help offset some of the build cost if anyone were interested.

Thanks
Jon

blue moon:
are you sure this is the way to go? You should be able to pick up an older Metal Halide unit for about $1K. It is a much smarter purchase than building your own.
It will have a properly calculated distance from the bulb, a good working vacuum setup and will expose any emulsion you might want to use.

There are many, many sub par and poorly performing LED units on the market and these were designed by the companies with an R&D team that supposedly know what they are doing. Don't take me wrong, it is certainly doable (Lou designed one that is now sold under Vastex name and still has the best field distribution I've seen), but is it worth it? You will have several hundreds of dollars into a DIY and for just a little more can go into a pretty nice unit.

pierre

blue moon:
oh, and that LED layout will cause massive hot spots/variations in the light field. The distance between the LEDs has to be the same in all directions. You will need to get strips closer if the spacing on them is represented correctly.

pierre

mk162:
I'd listen to Pierre on this one...

Maxie:
I have a home built unit, I have a Saati led light about 40” below the glass.      It’ s not that expensive and is made for the job.      I think Saati have 2 units, I have the cheaper one.
I would also recommend that you have the rubber seal sitting on the glass, I built it with the seal on the metal frame and this gave me trouble.
I had an electronics guy set up two timers so the first one switches on the vacuum for a set time and then the lamp switches on.
Good luck, don’t try and save too much, to do good printing you need good screens.

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