I have a couple of DT750 motors, well known from David Windestal’s first tricopter. These were my first order on hobbyking, so they’re old… really old. Shafts have been slightly bent from repeated crashes, but dt750s look good. I had the sudden urge to build another quadcopter the other day, and me, being cheap, I used what I had at hand. I really want to use a proper propeller hub/mount, so for those DT750 motors, a shaft replacement is in order. Non-threaded of course.
DT750 motors, looking good
I bought the shafts for A3548 Series Motor from RCtimer (http://rctimer.com/product-544.html). Mind you, the picture on their website isn’t exactly what you get. The ones I received, only had one groove for the C-clip, and it wasn’t the one on the end.
Since the shafts need to be shortened anyway, this wasn’t that big of a problem. So I cut the shaft just in front of the groove, leaving some “meat” so the clip would be secure.
No groove at the end
There is also a bigger groove to be made for the screw, to hold the bell in place. Mark that with a pen or something, and go to town with a file. I used a cutting disk and a dremel. You can see, on the picture, the old dt750 shaft and four new, freshly cut shafts.
Bigger groove for the screw
Remove the C-clip on the bottom, don’t lose the spacer!
Remove the C-clip
Don’t lose the spacer
Now, separate the bell from the windings.
First, you need to remove the old shaft, you can do this with a hammer. Remember to unscrew the tiny screw, holding the shaft in place. Hit the shaft lightly, until it falls out, and replace it with the new one. Be careful to line the groove with the screw.
DT750 bell, separated
It would be a good idea to replace the bearings, but I didn’t order any, so this will be a project for another day. This is how they look like. The size is 8x4x3 (total dia, inner dia, height).
DT750 bearings
Reassemble the whole motor, don’t forget the brass spacers and C-clips. I also ordered some prop adaptors, so the whole assembly looks like this
DT750 motors with prop adapters