25mm gearmotor questions (bl-conversion)

[ralf.96]

Hi,

I´m currently planning my first bw and got some questions about the 25mm motors.
I´ve already found out there are good but also some bad ones. Is the difference the gearbox or the motor? (I´d guess motor).
Since testing with my raptorweight featuring blheli-flashed escs has been quite successfull so far, I´m considering going straight to brushless. If the motor would be the faulty part I´d use cheap ebay motors and wouldn´t "waste" Elli´s good ones. For choosing a bl-motor it would be helpfull to know what ratio the gearbox (f. ex. of the 1000rpm motors) has and what diameter the shaft of the motor itself has (I´d like to reuse the pinion).
Or if somebody got a proven bl-setup providing similar performance as good 1000rpm motors I´d be keen to hear about it.

Thanks,
Ralf

[Pinski1]

I am using 1:500 12V 25mm DC motor gearboxes with Turnigy SK3 2118 2250kv brushless motors. I removed the 2 black countersunk screws as they have no purpose for it's new use and could catch and rip wires. I replaced the shaft with a longer 2mm shaft to fit the original brass pinions on the motors.

[ralf.96]

Thanks, that already helps a lot! 1:500 is a typo, isn´t it?
Do you still know at what rpm the gearbox with the brushed motor was rated for? Most dealers don´t state the gearratio, but rpm at a given voltage.

[Pinski1]

Derp, yeh, 500rpm gearbox. The BLDC motor spins at double the speed the 25mm DC motor does, so you double the gear down ratio to get back to ~1000rpm.

There is some more information on 25mm gearboxes and motors here: http://sparc.tools/forum/index.php?topic=166.0

[ralf.96]

If anyone is interested, this is what it resulted in:



I ended up using:
-ebay 500rpm gearboxes
-SK3 2122 2100kv motors
-afro 20a slim flashed with bl-heli (had them leftover from a multirotor)
-3s lipo
-approximatly 55mm wheel diameter