You might recall that I tried printing this fake lens last week and found it quite challenging.

So today for S&G, I figured I’d try to print it in two halves like so:

Sliced lens halves

Then instead of gluing or epoxying them, I joined them with acetone: it’s quite a thin profile, so it’s a good test of the strength of the bond.

Well, I let it cure for half an hour just to make sure all the acetone inside the bond had evaporated, and it certainly is plenty strong! Strong enough to take a vigorous chemical polishing - with acetone also - while applying a fair amount of pressure and stay in one piece.

I polished it by hand for 5 minutes and it’s even a bit lens-y now 🙂

I’ll let it cure for another 24 hours for good measure, then tomorrow I’ll mount it in the lathe and I’ll polish it some more with acetone, to see how clear I can make it.

It’s never going to be any good of course, but it’s interesting to see how much it can be improved, if only to find out what I can do with PLA.

    • @[email protected]OPEnglish
      12•3 days ago

      Yeah I read about others trying to make optically usable lenses. That would be great!

      But my purpose was to print a dimensionally accurate template for my 3D-printed frames.

      That went south because printing this object in one go with a FDM printer is almost impossible to print cleanly. So I gave up on that. But I was still curious to use it to find out if I could use acetone to reassemble two clean halves of it, and find out what kind of polish PLA can take.

      You know, just out of curiosity 🙂

      • @[email protected]English
        4•3 days ago

        Might find this interesting, uses abs, there’s an example at the end of using one of the fdm printed lenses with lasers

        I’ve tried with petg, was just for looks (transparent cases) rather than optical use, wasn’t super satisfied with it. Might try abs, it takes to acetone smoothing really nicely

        • dual_sport_dork 🐧🗡️English
          4•3 days ago

          That was a neat read, and the author managed to achieve some impressive results that I can tell you from experience will require settings that engender hella long print times.

          I think it would be significantly less irritating, especially if you were going to be doing this type of thing on the regular, to print molds of the negative of your object with your FDM printer and then cast the final product in resin which will be inherently solid and (theoretically, done correctly) consistent and without the possibility of internal voids.

          I mean, if you’re going to be hand-polishing the shit out of everything at the end of it anyway…