Tuesday, February 2, 2021

Another probe nose 3D print

Our next design for the probe nose has it in 2 pieces, to avoid messy supports. This is what it looked like, just finished:

The idea is for these parts to be glued together after cleaning up and finishing. The following are the steps involved in cleaning the 10-32 threaded bits. In general, it's hard to do that without damaging the threads. One of the holes had bad threads, which I tried to chase with an AN3 aircraft bolt (which is 10-32 threaded) and this improved things a bit, but still. It may or may not be related to the horrible de-laminated layer indicated on the part, which in turn may be related to our attic maintenance people slamming some huge heavy thing onto the ground just outside the garage where my 3D printing was taking place.

The universe conspires against us at every turn. :)

The take-home lessons from today's episode of melting petroleum products and squooging them into weird shapes are:

  • The overall plan of a 2-piece nose with threaded holes for the 10-32 barb adapters is sound. There are no show stoppers at this point.
  • Next time, keep trying more ideas:
    • One possibility is to print without supports, and design the threaded holes to have "domed" or "conical" tops so there is not a lot of overhang when filling them in.
    • Another idea is to change the cutting plane where the two pieces are "split" -- so that the threaded portion is in one half, and requires no supports, and the un-threaded portion is in another half, and contains just the teeny tiny 1/16" holes and channels.
  • Longer term, the actual nose portion is a good candidate for making in SLA or SLS, perhaps at Shapeways. This probably applies to the "barometer shroud" as well.
  • Having gotten a reasonable thing to work for the probe nose, we should proceed to print another copy that does not have the horrible de-laminated layer, and then move on to another test "kit build" of the probe to verify that all the bits work as intended.

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