MCM Intro: Trap Door, Arm Axle

Our most critical module is our raking arm/trap door mechanism. The components that comprise the entire feature are (including expected costs):

Part	Cost of entire stock	Fraction Used	Cost of part
Arm	4.06	0.92	$3.72
Trap Door	12.07	0.05	$0.58
Planetary Gearbox	14.25	1.00	$14.25
Gears	5.37	1.00	$5.37
Axle for trap door	2.90	0.75	$2.18
Axle for arm	2.90	0.75	$2.18
Extra axle for gear	2.90	0.25	$0.73
Rigid Coupling	0.00	0.00	$0.00
Arm Lip	13.82	0.03	$0.44
Total			$29.44