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Author Topic: geting my head round motors  (Read 1775 times)

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Offline crash_ndieTopic starter

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geting my head round motors
« on: August 16, 2010, 10:00:41 AM »
i thought id get my head round motors and gearing by upgrading my little girls electric car its to slow for her now. the motor it self is suprisinly small running  3 gears how can i work out what size motor is needed to keep the same pull but pick up the speed and make it faster ? also am changing it from a 6v system to a 12v 1 ill need a charge system? am thinking of using the same drive system for my robot but again it will need to be faster  helllp !!

Offline waltr

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Re: geting my head round motors
« Reply #1 on: August 16, 2010, 10:28:23 AM »
Hint:
Gear reduction decreases output rpm and increases torque by the amount of the reduction.

You can measure the speeds of the current motor/gears and use the SoR motor calculator to get some feel for what is needed.

Offline crash_ndieTopic starter

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Re: geting my head round motors
« Reply #2 on: August 16, 2010, 01:02:04 PM »
have i worked this out right? if i turn the final drive gear a full revolution by hand  an count how many turns the motor does this came out as 178-1 , if i then power the motor for 1min an count the number of times the final drive turns over the minuet witch came out at 51 ....

178 x 51 = 9078 rmp at the motor is this right ? 

Offline waltr

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Re: geting my head round motors
« Reply #3 on: August 16, 2010, 01:42:20 PM »
Looks correct.

Offline crash_ndieTopic starter

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Re: geting my head round motors
« Reply #4 on: August 16, 2010, 01:56:01 PM »
whoooo rite all i have to do is find a 12v dc 2000 rpm motor that's 27mm wide and 40mm long with a spindle of 3mm across hummmm any ideas lol

Offline blackbeard

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Re: geting my head round motors
« Reply #5 on: August 16, 2010, 02:03:32 PM »
"sure, you can test your combat robot on kittens... But all your going to do is make kitten juice"

First step: Build androids with AI
Next step: Give them vaginas

Offline crash_ndieTopic starter

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Re: geting my head round motors
« Reply #6 on: August 16, 2010, 02:07:27 PM »
lmao now that would be mint ! but dont think missus would be to happy with it  ::) women spoil all our fun :D

Offline crash_ndieTopic starter

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Re: geting my head round motors
« Reply #7 on: August 17, 2010, 03:16:05 PM »
humm dun my maths wrong it needs to be 20.000 rpm motor i need i dont think they make them that fast do they ?

Offline waltr

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Re: geting my head round motors
« Reply #8 on: August 17, 2010, 04:05:20 PM »
If you want to use the same gear ratio and double the output speed then you do need to double the motor RPM to about 20,000.
They do make motors that run this fast but they do cost more. Another way to to change the gear ratio or replace the motor/gear box with a gear motor that meets your requirements.

 


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