Replicating the mini thunderbolt

[Frotz]

That's the easy part of the problem. Positioning N slots is easy; just do 360 / N. Now consider two sets of slots stacked. If you have one slot right on top of another, that side might be lighter than the other side and therefore the chopper will be unbalanced. The problem I want to solve is how the top set should be aligned with the bottom set to minimize any imbalance. If N1 is divisible by N2, then simply putting one slot on top of another will work. With N1 = 5 and N2 = 4, that's not so easy.

What you do is model and print the rotor with no regard to balance, then when you get it, balance it.

I'd rather get the math right and only have to do one or two prints.

[sirendude2012]

That's the easy part of the problem. Positioning N slots is easy; just do 360 / N. Now consider two sets of slots stacked. If you have one slot right on top of another, that side might be lighter than the other side and therefore the chopper will be unbalanced. The problem I want to solve is how the top set should be aligned with the bottom set to minimize any imbalance. If N1 is divisible by N2, then simply putting one slot on top of another will work. With N1 = 5 and N2 = 4, that's not so easy.

What you do is model and print the rotor with no regard to balance, then when you get it, balance it.

I'd rather get the math right and only have to do one or two prints.

I have the impression you meant to edit the 3D model so it'll print pre-balanced. You could do that, but it would be too much money, time, and effort. The thing is, it doesn't matter how much math you do, the plastic doesn't have 100% consistent density. Neither does metal, otherwise you wouldn't have to balance things. Even vacuum cleaner impellers have to be balanced.

What I mean by balance it is that when you receive it, take a drill and drill out some plastic on the heavier side.

[Frotz]

I'd rather get the math right and only have to do one or two prints.

I have the impression you meant to edit the 3D model so it'll print pre-balanced. You could do that, but it would be too much money, time, and effort. The thing is, it doesn't matter how much math you do, the plastic doesn't have 100% consistent density. Neither does metal, otherwise you wouldn't have to balance things. Even vacuum cleaner impellers have to be balanced.

What I mean by balance it is that when you receive it, take a drill and drill out some plastic on the heavier side.

Note that I said "minimize any imbalance".