[EricH]

I'll answer on the 8 boxes. For each gear pair in the gear train, the driving gear is the one that is GIVING the power to the next one. Each driven gear is receiving the power. If you have 3 gears, all in line, 1, 2, and 3, gear #1 is driving only, gear #2 is driving (#3) and driven (by #1), and gear #3 is driven only. If you are only using 1-2 reductions, set anything that's left to 1:1 ratio.

So, let's see if I read your setup properly: Two 10:1 reductions followed by a 4.67:1 reduction (the 18:84 change), with two mini-CIMs going into it. Then a 2.5'-3' arm, lifting 10 lb... I think that will work, maybe a tad overpowered but more is better than less in this case.