Are you sure you want a gearbox at all? My previous testing once suggested that equal speed/torque was best for a friction heater (may have changed in the months since then)
One coil doesn't get close at 1024/1024. 2 coils at a junction with a 2:1 to speed equals 2048/1024 just about gets there. The 3rd coil got me there.
I'm an idiot. I forgot that only the torque doubled with two coils. I even said even torque/speed, but forgot the gearbox was required to achieve it.
So the ideal ratio your 3 coils would be 3:1.
I blame Mondays.
 
				
		 
 
		 . Alas, I'm good... 3rd coil pushed it over the line, got the tungsten and now the bedrock breaker.
. Alas, I'm good... 3rd coil pushed it over the line, got the tungsten and now the bedrock breaker.
		
 (It's too much of a crutch when trying to get the best RoC experience)
 (It's too much of a crutch when trying to get the best RoC experience)