2021-09-10: I now sell a very small selection of coreless motors due to a younger relative taking out one of the motors by crashing their drone. When purchasing replacements, I had the fun task of attempting to figure out the rough no-load RPM of these same motors to try to match what was already being used in the drone... After managing to damage a motor during said testing, I decided it was also a good time to figure out what exactly a coreless motor actually was...and it is really neat! Check out the pictures below and try to remember that this motor body is [only] 20mm long with a 1mm diameter shaft - this motor is TINY!
Motor before its destruction!
This is a picture of the brushes - two metal springs to contact the commutator.
These are the copper windings. Commutator to the left. 1mm Output shaft on right.
Commutator end of the rotor. Who or what soldered the end of those wires? Huh...the commutator is rather marred from arcing... couldn't have been from the accidental overvoltage it experienced could it?
Shaft End view. Look at the nice crisp wire bends!
View of the magnet core
View of the business end of the motor without the shaft - notice the long bronze bushing that stabilizes the shaft.
Thanks to a local motor shop for letting me borrow their tachometer to determine the speed to the motor. Had to put a gear on it and paint one side black (white being the plastic color). This motor spins at 58,100RPM at 3.93VDC. Talk about balance - how do you balance this and keep it from self destructing? What about the bearing oil? This little motor is engineered very well for such a inexpensive little part! How do you make something like this and sell it for $1.00?
As always - these pictures are high-res. Right-click and open in a new tab or click download to view them in better detail.