I love my sk3’s, let’s start with that. They’re 6374, 192 kv, they’re simple and they just work. At the time of writing they’re still chugging along pretty well. However, starting about a week ago I happened to notice that when I roll the board by hand one of the motors and the it’s wheel wouldn’t turn.
I tried by hand and felt resistance and when I looked closely I found that the drive gear has been “milled” and the shavings are getting into the motor can:
I’ve been using these for over two years now without issues so I think part of the problem was also that the mount was a tad far from the the wheel gear, thus creating more diagonal tension and pulling the drive gear into the mount over time. The shaft is a bit short, though I was careful to leave a space between the gear and the mount.
Here are my questions:
1.If this can be cleaned and repaired what’s the best way? Full disassembly and rubbing alcohol on all parts? Something else? This would be my first time opening a motor so I’m prepared to make mistakes but I’d like to try to save them.
2. If I do need to replace them can I use exactly the same type (sk3 6374 192kv) without having to go through motor detection, vesc settings etc.?
3. Are there any comparable sealed motors that are known to run relatively cool?
Thanks very much!
You get to find a torch, Compressed air, good Alen keys, ring Clip pliers (circlip, snap ring?) and an all plastic tooth brush.
In broad strokes, you take apart the motor can off the stator without scratching up up axle too much.
Inspect bearings and magnets. If there are grub screws holding the assembly together, heat them as it is almost certainly secured with red or green locktite.
Don’t cook your magnets, don’t agitate your windings, don’t mess with your hall sensors if you have them.
When you figure out what was causing the resistance, remove it. Don’t crush your fingers sliding the can back over the stator.
Don’t “slam the bolt home” either, could also crack magnets.
I don’t see why you couldn’t clean it out. It might be tricky since the metal shavings are probably attached to the magnets so it will takes some work.
That occurred to me. That’s why I thought maybe some alcohol would help “wash” the shavings away.
I mention all those things as I have most definitely done each one exactly wrong. Maybe you can cheat and blow it all out with compressed air.
I can try that, get a can of the compressed air used to clean PC’s, though I’m guessing there would still be some stuff left, probably on the magnets.
What may work is using the sticky side of some tape, press it over the filings and remove. Do that before blowing air, remove as much carefully & manually
Then nothing pulls ferrous metal away from a magnet like…well a bigger magnet, welding mags are cheap -
Compressed air can would not be strong enough I think. Maybe just disassemble and bring to a garage when it’s quiet, blast it there to finish.
Like @Arzamenable said with a few extras.
Wipe stator down with isopropyl to clean.
Painters tape on the magnets then remove to clear large debris stuck to magnets.
Cloth soaked in isopropyl to swipe between magnets. Take the toothbrush dip in isopropyl and scrub between magnets. Wipe between mags with clean cloth.
This worked well for me. I had chips and dust everywhere on the magnets. It takes some time but I could remove everything. Afterwards cleaned with alcohol.
If you open the motor you have to unscrew the black bolts first (one is shown in your pic). They are bolted to the internal plastic fan. I guess the SK3 has no circlip like the SK8. Maybe the metal chips got into the fan bearing or around the fan which causes friction.
If you use the brass tube in the proper length or in combination with washers between motor bearing and pulley then the pulley can’t move towards the motor/mount. Like I said assuming the SK3 has no circlip.
Glad you made this thread and that I noticed it. I have the same problem but not as big of an issue.
I purchased two 6374 motors and I was not told they had stuck pulleys. I tried cutting a stuck grub screw with a hacksaw before realizing the steel dust I was spiting all around my motor. It was too late I could see it all over it. Obviously it doesn’t stop it turning but I should probably service the bearings anyway.
Cleaning them would just go along with that.
Nice to have specific information on how to deal with this.
I wonder if a putty type material would be good too.
Yes, that’s a good idea. Since these are interned for planes I had to file the shafts a bit so the grub screws would have a flat surface to grip. At the time I taped over all the openings on the motor can, then I went to work with a dremel tool and grinding attachment.
You got me out of bed I want to look at my mistakes
Accidental really good pic
You can see the cut I made to try to get the pulley off. Just buy a gear puller you poor past self.
Damn, and I thought mine were bad. Are they stuck on because of loctite or rust?
I’m at work right now so I have to wait until tonight to look at them. I do have compressed air here, maybe some magnets too. Isopropyl is a little tricky to get, though doable. Is acetone okay or too risky?
I have no idea they are solid as fuck though. I see the rust in the grub screw holes idk if that is on the shaft if just left from the rusty ass bolts that were in there.
I had the pulley in the vice and I’m hammering on the motor shaft to get it out but no luck. Then idk I got distracted and decided to buy two 6355 motors but the sensor wires are fucked on those and they need new bearings.
So I paid $200 for 4 torqueboards motors but I have to fix them all. It’s something to do at least, I’m happy to get half off used motors for a little work.
Yes I agree stick tape would work best . Maybe wrap some double sided tape on a pen so you can reach in and rolling around.
If you have a wire wheel for a Dremel, it’ll kick off all the shavings…just don’t touch the windings
Poster tack or strip caulk (monkey snot for installing car windows) should be good for getting into nooks and crannies to get those shavings.
That’s a great idea!
Silly putty might work as well.
high pressure water works pretty well, but only with the motor dissembled, and don’t put it too close, I just use a faucet that it’s pretty powerful here, never risked with a pressure washer, and a tooth brush
Not gonna lie bro, I’ve done wonders with some good ass tape, Elmer’s glue, and compressed air