Big Johnny

Hey guy's check out the pictures and tell me if you have seen this before.

I have 2 KDA 36-10XL brushless motors. The shafts on mine step down, what would this be for? Photo # 1 Hobbycity Stock photo, #2 My motor.

mesh

Hobbycity claims the motor has a 5 mm shaft, it looks like yours has just been turned down to maybe 3 mm. I guess the factory changed it without telling hobbyking Maybe the 3mm shaft is more appropriate for the type of collets or spinners mostly used on that size motor. I doubt the step down has a purpose other than that.

groundrushesup

Often the shafts are milled to accept pinions with a certain ID - usually for helis.

1320fastback

I see the problem, if you turn your motor around like in the HK picture it will be o.k. and the step will not be there anymore

Did it come with a collet? Does it fit?

CHELLIE

the shaft is fine like that, the benefit is that the motor has larger 5mm bearings in it, and that makes it stronger IMHO take care, Chellie

cliffh

That is a great point Chellie. One that I missed completely. I couldn't come up with a good reason for the shaft being like that.

Cliff

cyclops2

The reason for that little " useless " step there. It prevents anyone from pushing the prop saver OR prop adapter tightly against the snapring and causing friction if the snapring reaches the outer stationary part of the bearing. It is a standard feature on all well designed motor shafts.

Heli motors have the shaft comming out of the large rotating magnet housing. The shaft is set screwed to it. The step is not needed on them.

Still, the same shaft design CAN be used on both types to reduce special parts inventories.

cyclops2

I know of the following mm shaft sizes.
2.3
3.0
3.17
3.2

I would be VERY SURE of the fan rotor hole size before selecting ANY motor.
Also . Sometimes the motor shafts are a little Fat. Run it at VERY LOW speed and gentle pinch a super fine sandpaper on it for 2 second at a time. Keep checking the fit, so you do not over do it.

cyclops2

The BP A2217-9 970 KV has no step. 4 mm all the way. Sturdy looking motor.

Maybe it will be good for using in unplowed fields ?