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Reading all about the droplit and watched a DLP projector mod video.

It seems that the key is getting the UV filter removed from the projector's bulb, and then getting the zoom and focus to be nice and close.

What if we also replace the projector bulb with a high-power UV LED? I have some that can run 3 to 5 W. Now I know the original bulb was probably 100W or something, but what percentage is actually UV?
These LED's I have used put out very little visible light, and a LOT of UV. If they put out significantly more UV than the original bulb it seems that would be a good thing, especially when I saw used DLP projectors selling for under $100 without a bulb.

They have a pretty wide angle (100 degrees?) so collimating them seems like it might also be required. If several can be used to get a nice collimated beam of UV, I would suspect that it could easily exceed the original bulbs UV output by an order of magnitude or more, and If I am not mistaken that would enable much higher printing speeds.

The nice thing about most DLP projectors is that you don't actually *have* to remove the UV filter...most of them will work for curing resin right out of the box, though removing the filter will speed up print times.

There have been a few people around the web who've experimented with swapping in UV LEDs, with mixed results. Basically, it can be done, but it's a huge pain in the ass. You have to remove the old bulb (obviously), find and jump the protection in the projector (to make it think the original bulb is still there), heatsink and properly position your LED, collimate it (like you thought), and provide a way to power it. And you'll need stronger LEDs than you think...resin like MakerJuice is way more reactive in the UV A range (365nm or so) than in the near UV, so unless you're using those invisible, strike-you-blind LEDs, you're probably overestimating their effectiveness.

That said, it can be done, and if you want to go for it, then go for it! Just take lots of pictures for the rest of us. ^_^

The UV LEDs that I have a source for are centered on 400nm, with output from 390-410. My quick thought was that it would still put out more UV at 400nm than the original bulb. The original bulb might put out more at 365nm, so it would take some experimenting to see if it is worthwhile.

a UV laser might be really nice for this, although I can see that costing way to much... I can get those UV LEDs for like $2 each or less.

There are always going to be challenges.