Sk3 motor waterproofing?

@barajabali if you are standing behind the board when its resting on the wheels. When you print it you can verify in your cam software by seeing if the blades are angled backwards from the direction the motor will spin. @wmj259 im not sure what you mean, like have it so the air will blow up the can of the motor?

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In your description for 2.2 on thingverse, what do you mean by “bottom mounted” motors?

My new motor won’t be here for a few weeks and my current one is already trashed. So I’ll wait until you have the designed finalized. Any more plans for revisions? Thanks!

Im talking about the motors that are mounted under the board, so they encounter a lot more road debris (curbs, rocks, sticks); I would feel safer personally with a stronger fan cover. However if your motors are mounted backwards and angled up like on @barajabali 's mountainboard, then they will only encounter small debris so they don’t need as strong of a fan. As of right now im satisfied with the current design for my use. If someone raises a good design idea though i’ll change it.

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Gotcha. Looks good. My only request would be a combination of 2.1 and 2.2. So the blade height of 2.2 combined with the “plate” thickness of 2.1 for added strength. I use a single-drive, so length is not really a concern for me. But the motor is mounted underneath in front of the rear truck and is subjected to more impacts (see image posted above where I broke a motor winding from an impact)

No worries if you don’t have time. Look forward to printing this guy out!

@jmasta ill see what I can do :grin: ill make one that extends out to the end of the axle to give it bigger fans for people that aren’t worried about the motor length sometime this week.


Ok I will have to try them

Will it fit a 63 mm sk3

@Caleb1 yeah it’s made for 63mm sk3’s. I’m using them on my 6374 motors

@jmasta I just made a new version for you :slight_smile: just as thick as the others, and has wide fans. V3.1


Awesome. You’re the best! :sunglasses:

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What I meant was not only is it a fan but if you have like a hollowed cylinder that covers the motor can. It’ll be a fan and double as a motor can cover

I haven’t checked this for myself but I’m sure you guys will know. In what direction is the air flow on the sk3 motor? Going out the back? Or the front (by the extended shaft) Or does it depend on which way the motor is spinning?

@barajabali Its got a metal fan inside that spins with the can so it depends on what direction is spinning. So yeah. On a standard dual setup one will be sucking in through the back and the other out

@barajabali @krloz The standard fans on these are flat blades that act as a centrifugal fan. Regardless of the way the fan spins, the flow is always outwards from the fins.

Therefore the flow always comes in through the back and out the front regardless of direction the motor spins.

E: I may be wrong. I’m looking at two different pictures and it seems like on one, the blades are flat but on the other that they have a slight curve. This is important, as the flat blades would mean it is a centrifugal fan and the above applies but if the blades are curved then it might be axial fan which blows air in one direction, when reversed, the flow rate would be much lower and the fan would be a lot less efficient so I doubt this is the case but you never know!

Maybe it differs from motor to motor

This one had the same fan mine has. At 4.39 you can see the blades are flat but at an angle do they will push turning in one direction and pull turning on the other


Can the fan’s orientation be flipped?

My motor spins counterclockwise. However after looking closer at the fan blades, a clockwise rotation would produce the best airflow

Edit: CCW vs CW depends on which side of the motor you are looking at. Mine is actually spinning CW, as viewed from the front of the motor

If you mount it upside down you would still have the fans lounging on the same direction. Think of the letter S. Turn it upside down and you still have an S. Not a Z

Good point. Haha

In case you were wondering, the airflow direction is always in the end of the can and out the holes near the shaft. The direction is the same for both CW and CCW rotation

Careful trying to analyze flow by the looks of a fan! It can be very deceiving and counter intuitive.

The best way to determine flow on small scale is by using string or yarn held near the inlet and seeing which way it flows.

False. If you mount an axial fan backwards it will produce airflow when turned the other way otherwise we wouldn’t have cw and ccw propellers in aviation.

And an S upside down is an S…? Depends on your axis of rotation. Draw it on paper, and turn the paper upside down so that you are now looking at the back of the sheet and tell me what you see.

If this is the case, then I was right before and it is a centrifugal fan. If you want to experiment on which way it would be more efficient, you could spin the motor with no load forward at x rpm and measure the power draw, then do the same turning it in the opposite direction.

If you post some high res pictures of the fan, I can help you in figuring out which way it should be mounted for higher efficiency based on shape, angle, and rotation direction

Clockwise appears to be slightly more efficient, based on torque/efficiency curves

However the difference is so small, I don’t think it’s worth stressing over. I prefer to drive the toeside rear wheel. I’ve ridden both ways, and toeside rear drive gives more control in a tuck, since your heel usually isn’t even on the board

SK3 6374 149KV Clockwise:


SK3 6374 192KV Clockwise: