rewind a dc motor

[rsteng2]

since cytron sell dc motor, does cytron provide service or by any chance possess equipments or skills to rewind motor?i want to rewind a motor but are stucked by lack of understanding about the theories.

[ABSF]

since cytron sell dc motor, does cytron provide service or by any chance possess equipments or skills to rewind motor?i want to rewind a motor but are stucked by lack of understanding about the theories.

I have dismantled and unwound quite a lot of motors from Harddisks and video machines, but never tried to rewind one. Transformers yes I have rewound one or perhaps two. First you have to get a coil winder. The China-made one (manual) cost a little over RM100 and I only used it to count number of turn of the relays that I unwound.

Was your DC motor so expensive that your need to rewind it? From unwinding the motors, I know that it is not that easy to rewind one.

Allen

[rsteng2]

thx, allen.but the reason i want to rewind my motor here is to increase the speed of the motor.although many net sources show most rewinding results in failure,but the thailand robocon team make the speed they want by rewinding the very same motor.below i will show the image of the windings of the motor.is it possible i can succeed by hand-rewinding?

[rsteng2]

i just learned that with less windings, rpm can increase only down to a certain number of windings, or else current drawn will be over the max..i will give it a try..bless me.

[rsteng2]

succeed, by decreasing the windings by 4 times lesser,the rpm also increase by 4 times.

[ABSF]

succeed, by decreasing the windings by 4 times lesser,the rpm also increase by 4 times.

Just curious Reducing the number of turns by 4 times and the rpm increases by 4 times, does that mean that the current is also increased by a certain factor? Is the copper wire size still remains the same or you rewound the whole thing with thicker wires? How about the commutators, is it sparking when the motor is ON?

I have bought DC motors for my battery operated screw driver, and I found that it runs hotter and much faster than ordinary motors. When I opened it up I found that it has thicker wire and not so many turns compared to regular motors. I think toy sports cars motors also use the same principle to increase their speeds.

Allen

[robosang]

Woh, how fast is 4x? Want to see it. Very nice work! Can the coil withstand 4x current in that case?

[rsteng2]

sorry for the late reply.the original speed is about 100-140rpm.after rewind,it get to 410-450rpm. and about the current, i am sure the current withdrawn is higher,as decreasing the number of windings decrease resistance.but i am not sure can ohm's law simply be applied here, because inductance also play a role. however, its clear the motor gets hot easier.and i rewind using a thicker wire of gauge 26, original is gauge 29.since the info i get is 30 windings for gauge 29,29 windings for gauge 30, so i just choose 33 windings..there should be an easier method to figure it out..for the spark...6 motor is rewinded, some have, some dont have.

[ABSF]

That's awesome. So someone who wants to increase the RPM of a DC motor can refer to this post, or to you.

Allen

[rsteng2]

i will try to figure out the calculation,whereas for the winding skill,i refer to http://www.rccrawler.com/forum/electronics/3160-winding-motor.html and http://www.youtube.com/watch?v=nbhw78P05TU. thats all needed i think.