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NYC Resistor members recently spent an evening playing around with resin:

For today’s #hackfriday at NYC Resistor a bunch of us were inspired by Junior and ScribbleJ‘s 3D printing projects and experimented with UV curing resin using a DLP projector.

We had some JMP UV stamp resin, although it didn’t cure solid with the normal projected image in our test. Even with thirty minutes of exposure, the resin was unchanged in viscosity.

As a next step, we removed the DLP’s mercury arc lamp and drove it positioned just a few cm directly over the resin.

With the interlock defeated and proper safety precautions, the result was a very quickly cured puck of resin. Which is good news, since it means that there is enough light intensity around 380 nm.

[photos by Trammell Hudson and William Ward]

John Baichtal

My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal nerdage.net


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Comments

  1. arthur says:

    You want to remove the UV filter ( probably attached to the lamp block ).
    But then you’ll also get tons of IR thru where it shouldn’t go, so either replace the UV/IR filter with a IR filter, or be very careful about the optics heating in your light path ( broke a DLP that way ).

    Arthur from Lemoncurry ( come chat with us on IRC ! )

    1. technomads says:

      Thanks for the suggestion! We removed what I believe is the UV filter that was directly in front of the lamp, right before the lightpath went through the color wheel. We measured good curing of the stamp resin all the way up to the last optic stage before the DLP itself, after which the resin no longer cured.

      The Bucktown polymer resin arrived today and we’ll give it another try on Saturday.

      1. arthur says:

        Ok that’s good you have the UV filter removed. Unfortunately, that used to also filter the IR, and take all the heat. The next thing in the light path ( can be a lens, or a square light guide made of mirrors ), and now when you put the lamp back in, that’s going to take all the heat. If it’s held together by glue or plastic, that’ll be in trouble.
        In my first DLP, the light guide was fine, but the lens after it was attached by plastic, that melted and the lens broke.
        In the second ( today ) the light guide’s glue burned, I replaced it with super glue, and attached it differently, and now it’s all good, have been running fine for an hour.

        I recommend you be very carefull and watch it closely, and shut it all off if you see smoke :) ( or even before that )

        Also don’t hesitate to unsassemble quite deeply, to be sure to see everything clearly.

        1. Jon Watson says:

          Arthur, I just fried my light guide last night after taking out the UV/IR filter in my BenQ 1080st. The coating on the light guide glass just baked right off after removing the UV/IR filter from the lamp housing. The projector still seems to function ok without the light guide. I put the UV filter back into the lamp housing until I can get an IR blocking filter to put in the light path, probably where the color wheel was. I moved the color wheel to an empty space on the other side of the lens. I was wondering what this part was called until I ran across this post. Let me know what other insight you may have on projector mods do’s and don’ts. Seems I learned my first “don’t” lesson.

    2. technomads says:

      We had some success with the better resin this weekend: http://www.flickr.com/photos/osr/6935073638/in/photostream

      But the projector smoked, as you had predicted. We now have a dark spot on the projected image that might be smudges on the lens or perhaps something worse. Things are on-hold until we fix that.

      1. arthur says:

        I hope it’s nothing.

  2. elpoulpo says:

    A quick note on your last comment : seing the resin cure doesn’t necessarily mean you have 380 nm emissions. With high light intensities, i.e. density of photons, two 760 nm photons can be “seen” by the material as one with twice the energy, corresponding to one 380 nm photon. Not sure if it could explain the result in your case, though.

  3. sgraber says:

    Please, use proper personal protection equipment like gloves and goggles/safety glasses! It drives me nuts to see people handling wet, partially cured resin with bare hands. This is stuff you *can* get sensitized to if you’re not careful. I worked with UV curables for almost 15 years, so please spend the little additional time to protect yourselves when working with this stuff.

  4. Jason says:

    Wouldn’t it be easier/less expensive to remove the quartz filter off a 20$ halogen lamp then futzing with a DLP projector?