Repurposed UV Curer Makes Your Prints Hard As Nails

The price of resin printers has dropped significantly in the last couple of years, and it’s down to the point where you can pick up a fairly decent DLP machine for less than $500. While this is great news, you still need several things beyond resin for successful prints, like a way to do post-process UV curing.

[Inhibit] picked up the formidably-priced Wanhao D7 awhile back. Rather than spending another printer’s worth of paper on a UV curing box, he rescued and repurposed a small commercial curing device meant for gel-based nail polish. You stick your fingertips in, switch it on, and it runs for 60 seconds and then shuts off.

It’s a great idea, but unfortunately prints don’t cure as fast as fingernails. So the first order of business was to bypass the dual 555-based timing system by wiring the UV LEDs directly to power. The manufacturer never intended for the lights to run continuously, so to keep the board from melting, [Inhibit] added in a small 12 V computer fan for cooling. There’s even a little printed grille with angled fins to keep UV light from leaking out and burning nearby retinas.

[Inhibit] also designed and printed a tray for the prints to sit on, and a front enclosure piece to focus as much light on the parts as possible. Files for both parts are floating around the Thingiverse, and we’ve got the build video all cured queued up after the break.

These little commercial boxes don’t cost all that much, but you could always just build your own.

28 thoughts on “Repurposed UV Curer Makes Your Prints Hard As Nails

      1. The germicidal tubes are horribly dangerous to living flesh on the biped mammal scale, not just single cells. They’ll burn your eyes or skin, causing irreversable damage before you really notice. They’re only allowed in commercial equipment if they’re kept well away from any possibility of the light reaching human flesh. Even the cheapest EPROM erasers have mechanical interlocks to keep the bulb cut off when they’re not shut up tight.

    1. All the nail-gel setters I’ve heard of use UV LEDs. I think the frequency isn’t high enough to wipe EPROMs, and the power’s also a bit pathetic and lacklustre. I wouldn’t expect great results.

      That said a real tube-based UV source isn’t exactly complicated. If you can program an EPROM you can certainly wire up a little 8W or 4W tube. Check specifically that the tube is suitable for the purpose, because there are several wavelengths of UV source available.

      Then again, the LED ones are dirt cheap so I suppose it wouldn’t do harm if you know someone who wears elaborate nail varnish. Just don’t get bits of solder all over it before you present them with their “gift”.

      1. Did I ever write this up? I tried to replicate the results here, even going so far as to order some $5-ish high-output, low-wavelength (for LEDs) LEDs. Tried these on multiple EEPROMS — I think I left one for as long as 36 hours. Many bits flipped, but there was nowhere near clean erasure.

        Ordered an EEPROM eraser from China, $15ish, and it clears them all in 15 minutes. There are _no_ safety precautions with this device, however. It’s a switch, a timer, a UV bulb, and a plastic case. There’s not even a bulb holder — it’s soldered to wires. If you open the door, you get whatever UV bounces around and out. My procedure is to put the EEPROMs in, turn it on, and walk the heck away. Works very well for that.

        YMMV, but it says in the EEPROM datasheets that they want short wavelength UV, and the UV LEDs are longer wavelengths.

  1. Does anyone know of a good resource for eye protection when working with UV LEDs or light. While I try not to look at anything that is very intense, I would like to start a project that uses UV LEDs and would like the definite word on glasses.

    Thanks and thanks for mentioning this in the video.

  2. Has one of these! I harvested the least useful diodes out of it, not affecting brightness much. Incidentally these are 370 LEDs but best to replace them as blocks as they are in series. I also found a related product, an X something orange glue “pen” which had its LED pulled and put in a nice metal torch case with a slightly more sensible 4.5V so it runs and runs.
    If you have the earlier version that beeps its worth adding a fan so the LEDs don’t fry, as in this mod.

    You can actually get 290nm LEDs and they will indeed nuke e2proms, FPGAs etc.

    1. What’s the critical wavelength for eproms? I know 254nm from e.g. the clear tube germicidal bulbs will do it, whereas the 365nm stuff from the deep purple “woods glass” black lights will not. And most of the LED UV lights are as you said 370nm. So, where do you find 290nm LEDs?

  3. Someone in my local Hackerspace converted a microwave to a “nanowave” for curing resin prints- they just took out the magnetron and replaced it with high intensity UV LEDs, and a bunch of aluminum heatsinks. It is doubling right now as a sanitizing box and people are putting cellphones and whatnot in it, since it does output UV-C.

    1. did they cover up the door? These doors have a mesh that supposedly only stops microwave frequencies, right?
      Perhaps some aluminium foil would do the job just fine for light.

  4. Perfect timing, I just designed a digital uv lightbox controller that has pwm control and a user selectable timer. Currently shoved some uv led string into a metal paint can with one of those rotating solar display stands placed at the bottom, seems to work ok but gets pretty toasty.

    1. Thanks for the concern! I’m wearing the UV blocking safety glasses I go over in the video while I’m working on it. Believe it or not the nail curer I modified is wide open when in used as intended.

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