Just wondering if it is feasible to accurately reduce a steel motor axis (leopard 8072) to 8 mm? How accurate are lathe machines in that regard? Would the motor have te be taken apart completely to remove the shaft for machining?
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I work with sometimes with a lathe machine and I recently modified some trucks. Since the axle is long what I did is to create a cilinder that fits the other side and so clamp the trucks on both of the sides. It is still not perfect but that tollarance you get would be better than the on applied on most of the truck sold. Of course also depends on the lathe you have.
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The accuracy depends on how much you’re willing to pay to have it machined, or what type of machine you’re using if you’re doing it yourself. There’s CNC lathes that could hit a few thousandths of an inch tollerance, and there’s manual ones where you’d be hard pressed to be accurate to the nearest tenth of an inch. It all depends.
The shaft would likely have to be removed, it would make the machining a lot easier.
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OK, thanks for the info. Looks like it will be a matter of cost. Accuracy is going to be key.
Will ask around in Germany and get a few quotes.
I think @Eboosted once got a 10mm shaft lathed down to 8mm. He might have some info that could help?
I’ve read that 8mm shaft on this size of motors can break off actually.
lathes are precise, any lathe shop in your city will do it properly since lathes are expensive and a guy who doesnt know how to work with one cant afford it
chinesium shafts do, regular ones dont
I think you’d have to take the shaft off to lathe it. be nice to lathe it with just the motor spinning but likely would damage the bearings. but id doesn’t matter what type of steel the shaft is really and it doesn’t take much load and you could cut even a mild steel to precision. getting it to precision is a skill but you likely wouldn’t need much precision and almost all the shafts ive seen are a slide fit anyway. but whats the fit now …slide or press?
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I never did that. What I did was machining the inner diameter of the pulley to hold the 10mm shaft
Ops, my bad 
Not with the performance we get out of these motors. I’ll mainly go bigger for improved reliability.
i think the problem won’t be accuracy, cause you can hit 0.02mm fairly easy on any manual lathe. but i assume these motor shafts are hardened, if you machine away the outer part of it, most of that hardened section is gone. and your part is already weakened by the material you removed. and there was probably a reason the manufacterer decided to use a 12mm hardened steel shaft…
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Hmm, good point. Though I have no idea if quenching is something that only affects the surface of steel or not. Hardened steel is just a composition that is valid for the whole shaft.
I thought I have seen somewhere there are shafts with diameter bigger in the can and smaller after they came out. If I just could find it… What´s the length of your can, I mean which length the shaft would need till coming out of the can?
The shaft itself sticks out around 5 cm and needs to be reduced to 2.5 cm or so.
so the 12mm shaft need to be 15+74+10mm and than a 25mm of 8mm shaft right?
I found only 8 to 6mm now and something like ali baba where you can get your custome made ones I think
but that´s probably more work thou…
Nice motors 
unfortunately without sensors.
Is this for the 1:5 E-Toxx Drive? Because you could order spur gears with ID 12mm from Jenso and glue them on the shaft.