Quote Originally Posted by psycho_fling
hi all

my question to those in the know is, for the weapon if i am using a speed 900 motor on 15 volt (rpm= 8125) powering a 1.2kg axe head and handle using timing belts and pulleys, what ratio would give the ideal setup ??
I'm not in the know but I fancied a laugh using the australian's formulae

Firstly, you lack the handle length and power, so I guess 30cm handle and 15V*8A=120W
sweep= pi * 0.3m = 0.942m

Time =(2*Sweep^2*Mass/Power)^0.3
T=(2*0.942^2*1.2/120)^0.3
T=(2*0.89*0.01)^0.3
T=(0.89*0.02)^0.3
T=0.0178^0.3
T is roughly 0.3 seconds

Power*Time= Axe Energy
120*0.3= 36 Joules

[1/(2*Time)]*60 =Axe speed
[1/(2*0.3)]*60 =
[1/0.6]*60=
1.7*60= 100 RPM

Speed have/Speed needed = gearing
8125/100= 81.25(:1)

Not entirely impossible - a speed 900's 6mm shaft should fit straight into an RS worm gear. Feel free to laugh at my crap estimations and stuff.