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Making a keyway

Hello all,
i am going to order a sample of the 6374 330kv motor from may tech. i contacted them about odering with a keyway. they said that the minimum order quantity for motors with a keyway is 10. i don’t want to order 10 motors so i was wondering does anyone know how to make a proper keyway. i will have accesses to a mill soon with the robotics season starting so i will most likely wait till then to make the cut. i will need the dimensions a keyway for a 10mm shaft. any advice will be appreciated. an alternative is ordering 10 units with the keyway already made. i have the money needed to buy them but would need you guys to tell me if you would be interested in purchasing one.

Thanks for your time, Hans

that’s a really big, really fast motor.

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and i’m going to need to get some leathers and a full face helmet before i even think about strapping such a beast to anything i build.

I don’t want to discourage you from learning how to modify your own motors shafts… but it’s really not a good idea to do it on fully assembled motors.

if you want a 6374 motor you might consider buying this - available in qty of one! with keyway.

That is some super high KV! A keyway is easy to do with a rotary tool and a cut-off disc. You want to be sure you seal the motor up before you do something like this.

if you have a mill. do it like this:

i don’t even have keyways on the propdrive 270s on my 6S build. I just dremeled a flat spot for the grub screw to grab onto and that’s it. never once had a slip.

but keyways are better.

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I’ve done the same thing with my solar build- used one of torqueboard’s motor pulleys too, so it has two set screws.

Rookie-ish question: how hard is it to grind a flat spot on the shafts of these things for the screw?

Anything else that would need to be done to them? I’m good with my current r-spec but I have so many spare parts now that I’m thinking of getting one of these guys for a potential second ride…

Easy… It just needs a flat spot so the M4 bolts don’t backout on rotation. Doesn’t necessarily need to be 100% straight. At least my first motors aren’t and they lasted well over thousands of miles and still solid.

Do you have to remove the shaft to do it? (to keep the metal shavings out of it?) or can it be taped?

If removed, is that hard to do or hard to replace it back into the motor?

It is fairly easy to cut a keyway with a rotary tool and an abrasive wheel too.

You don’t have to remove it you can just tape it off. You just need a flat spot where the bolt/set screw is. If you run it without a keyway use M4 bolts and not the set screws. I think it has better grip and less likely to back out.

A plastic bag, some tape, a steel flat hand file (or a grinder) and about 5 minutes of determination.

@siggs3000 I used a Dremel tool to create a keyway and a flat spot. I don’t suggest trying to cut a keyway by hand. Just do a flat spot and an m4 bolt. I found my bench vice very useful to secure the motor. A gallon-size ziplock bag and some painter’s tape protected the insides from metal shavings.

Oh, and eye protection is a must!


Who does it by hand? I tried it by hand. No way was I going to finish it by hand. Maybe I had the wrong tool but even with a dremel, and tacon 160, it was like ten minutes probably a lot more. It’s a huge occurance for me. Preparing cleaning. Getting it done by someone on a mill or something better is nice. It seems the weakest link in the drivetrain (other than the set screw, which mine is loctited and stripped). I really like the tacon160 but it’s big drawback to rspec is not being Keywayd.
I’ve taken these completely apart regrettably as well as some turnigy 190kv motor. These have pressed bearing and very tight shaft the other not.
These are the greatest motors. Homage.

But I read maybe they are loud. The magnet fill was i forget but low at 71%. Maybe. Inefficient maybe? But it doesn’t matter and they’re beautiful and I’ve bought 6 I think. One reason I bought six because it’s so hard to find motor parts in this country. No stators. Easier to cut them out of tacon. Rediculous.

/me puts hand up
I do it by hand…
I own a dremel too… I should use it…

It was sychotiller. He said it just needs determination and a hand file. Haha and five minutes. That would be the hardest five minutes of your life

It’s not how you stir the pudding…It’s definitely the tool.
I just filed one the other day in 5. I could file all the way through it in 10.
Just buy good tools.

I’m laughing at myself though thinking about when I tried. Even with a dremel it looks bad and I question if it’ll hold. Amazing how tiny keyways, especially the tiny one on the motor shaft, must take all the torque