17 May 2021


One nice thing about knowing how to do simple math is being able to calculate volumes and apply density to get mass.

I'd assumed that the 3D printer we're employing would be using some form of nylon.

Nylon is about 1.14g/cm3.

JT's uses PLA which averages 1.32g/cm3.

That means I needed to make the void in the Energa a bit bigger.  Bonus!  It shifts the CG even farther back.  Getting more accurate by the day!


  1. Errr ...Ummm ... you sure about that?

    If I have this straight, you will be using PLA instead of nylon.

    If that is the case a void of the same size removes MORE mass. (1.32 > 1.14)

    If the goal is to match the mass, you need a SMALLER void.

  2. It probably could use nylon filament, but it's way more expensive and somewhat harder to use then PLA.

    Unless you really need the toughness of nylon, PLA is the way to go.

    1. It needs to support its own weight, take paint and survive being mounted on an FAL for pictures.

      I want it to weigh the right amount because... reasons. Silly reasons.

      JT's printer can do Delrin, if we really wanted it to be tough.

    2. Ackchyually, after a quick check, working with POM/Acetal filament sounds worse then nylon.

      But, a good PLA is very tough. You can even anneal it to increase it's durability.

  3. Well, aint I stupid.

    Focussed so hard on the mass of the void, I spaced on the increased mass of the non-void.

    Yeah, a bigger void makes sense.

    1. Let he among us without a "dur moment" cast the first stone.


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