Scale model rocket: how to improve?

Discussion in 'My Work In Progress' started by Hobbes010, Apr 17, 2013.

  1. Hobbes010
    Hobbes010 Active Member
    I've just received my first batch of printed parts. These will be used to create a 1:144 scale model of the SpaceX Falcon 9 rocket.

    One of the parts is in FUD:
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    The rocket nozzles each contain a hole all the way up to the support plate. This hole is small (about 1 mm at its narrowest point) and they contain a viscous liquid that won't drain out on its own. This could be wax, or the raw (unfused) printing material.

    For now I'll try some of the cleaning tips I've found here, but I think I'll have to change the design to prevent this in the future. I could make sure the hole goes all the way through, but the narrowest point will remain 1 mm (otherwise my walls would become too thin). Maybe I'd be better off making this section solid?

    I've also had comments that this part will be difficult to paint. To improve that, I'd have to remove the nozzles from the base plate, but that would make positioning them in a neat grid tricky. I'd like to provide locator holes that the nozzles would fit in. How much clearance would I need for the parts to fit snugly?

    Last edited: Apr 17, 2013
  2. UniverseBecoming
    UniverseBecoming Well-Known Member
    Perhaps putting it in the washing machine and running a spin cycle and trying centrifugal force to get the wax out. Of course you'd need to find a way to position the nozzles in the proper direction for it to have a chance of working. Or how about compressed air. I don't see how the wax could stay in there when hitting each nozzle with a blast of compressed air at, say, 90 psi.

    Then again, an ultrasonic cleaner as you've probably read about with the appropriate cleaner will dissolve it out as well I think.

    For painting, you could do a precision dipping process since all of the nozzles are identical, where you would attach the nozzle array to a linear actuator and then lower it into each color of paint to paint the rings letting each layer dry between dipping. When finished the nozzle ends would have several coatings of the colors used, but it would look real good if the paint use was not too thick.
  3. Hobbes010
    Hobbes010 Active Member
    I've drilled through the support plate, that got most of the wax out. Then I flushed the holes with warm water, and again with compressed air. There's still a small amount of wax in there, though.

    Dipping in paint is an interesting idea. I haven't gotten that to work properly, the paint was always too thick. My plan was to cut the support plate in three sections, so I can get everywhere with a paintbrush or airbrush.
  4. UniverseBecoming
    UniverseBecoming Well-Known Member
    Yeah I figured later after I wrote that that it might be a stretch layers wise.

    Perhaps with them separated you could turn the nozzles on a lathe like setup to get nice clean lines. Well, unless you have nerves of A450 steel alloy. :D
  5. Hobbes010
    Hobbes010 Active Member
    Each nozzle has a diameter of 8 mm, and the wall thickness is 0.5 mm. I think I'll paint the entire nozzle in one color. That's not entirely correct, but getting a shiny metal finish on bands 0.5 mm wide is beyond my capability.

  6. UniverseBecoming
    UniverseBecoming Well-Known Member
    Yeah, at that scale one color should look great.
  7. stannum
    stannum Well-Known Member
    Paint all in matte grey, wash with darker grey to get the lines more marked, then color the lines by drybrushing with metalic paint.
  8. Hobbes010
    Hobbes010 Active Member
    I've left this part lying around since my last post. The wax that's still in the nooks and crannies has turned yellow. Some of it has oozed out (on sunny days, with the part sitting in direct sunlight), but there's still some residue left.

    I've applied some Humbrol enamel paint to one surface. A week later, the paint is still slightly soft and easy to scrape off with a fingernail.