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30rpm motor to 3rpm


udaiveer

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Simple.

I had got 2 DC motors. A 30rpm and a 36rpm. (For 2GBP each!)

http://astro-graphy.blogspot.com/2015/01/30rpm-to-3rpm.html

These low rpm motor drives actually use a standard 200-300rpm dc motor with a combination of speed reduction gears.

l opened the top plastic part  which is the gearbox-housing and is the same for different rated rpm motors 

Both use (identical small) brass gears which means you can swap-change the gears combination to get different rpm outputs.

Lego! Without the Logo:-)

There are 2 types of reduction gears 4:1 (32t:8t) and 2:1 (32t:16t)

I took out a 4:1 gear from the 36rpm motor and put it in the 30rpm.

The IN gear is an 8teeth.

I put one extra axel(not needed) and a 32:8 (4:1) gear before the 2:1 gear which drives the output shaft. (1:1)

What  ever the numbers add up to... add input volts 3v to 12v variableness... 

After closing it , the shaft was turning at a little more than 3rpm. I put a 20t gear on it that drives a 60t gear with the 1/4-20 nut. A little faster than 1rpm about 1.3rpm.

...I tweaked the input voltage via a fan regulator switch and I got exact 1rpm with some load!

Photos here

http://astro-graphy.blogspot.com/2015/01/30rpm-to-3rpm.html

The top plastic part of the motor.

The gears are 0.5cm thick. 

OD. 2cm

8t 32t (on the ruler-scale)

The nut driver gear of 60t.

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Oh damn. The motor is waxing n waning but maintains 1rpm..

I think i have reduced the input voltage too much.

Also the AC-DC adaptor has different outpus 1.5v to 12v. I am using 3.5v

Also the voltage from the mains is dimmed-lowered which reduces the torque i think.

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Btw I reduced the 30rpm motor by adding a 4:1 gear(from another motor) I cant put anymore gears as the shafts are short and the gear box doesnt close properly and tends to slip gears.

So I am using just one more 4:1gear.

S

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A worm gear is the best speed reduction gear as it's only ONE toothed gear so to get a 30rpm to 1 I need a 30teeth spur gear being driven by a worm gear.

I got one from a children toy set similar to Lego.

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