Motor Shaft for RC Plane

[epanzella]

The electric motor shaft on RC planes is just a straight smooth rod. The prop is held on by friction via a collet with a threaded shaft on the other end. These collet arangements are Chinese aluminum and subject to big time runout and vibration. They also cause the prop to have lots of stickout off the motor so it bends easily. Mine had bent and needed to be replaced so I thought I would machine a new one with an integral prop mount for concentricity and durability. It's nice to see the prop finally spool up with no visable wobble! I was surprised at what a PIA it was to come with an order of operations as holding, machining, swapping ends and machining again while keeping TIR under .001 was quite a challange. I'm attaching pix of the original shaft and collet along with the new shaft I built.

 

[pontiac428]

Nicely done. I've got a box with some broken shafts somewhere... luckily, HK sells Turnigy replacements for cheap, as super small parts challenge my skills and patience. The threaded shaft is way more desirable than the wobbly collet!

Edit: Did you end up machining the retaining ring groove in the back? What was the shaft diameter?

 

[epanzella]

Nicely done. I've got a box with some broken shafts somewhere... luckily, HK sells Turnigy replacements for cheap, as super small parts challenge my skills and patience. The threaded shaft is way more desirable than the wobbly collet!

I bought 3 new shafts from HK for $2.45 each. That was plan B if I couldn't get mine to work. (but it did!!!)

 

[epanzella]

Edit: Did you end up machining the retaining ring groove in the back? What was the shaft diameter?

The shaft thru the motor was .2365 (6mm) and the threaded part was 5/6x 24. I left 3/8" at major D to pilot prop hub. This is a relativly large motor designed to replace a .46 glow engine so it doesn't use the retaining ring. The shaft has a flat spot at the rear and is held in by a collar with a setscrew. The motor is in a 57 inch Corsair.

 

[pontiac428]

Ah, I thought that was a bigger motor. A 6mm shaft is pretty meaty compared to my little planes. The last one I had in my lathe was 4mm OD with a 3mm circlip groove. In stainless piano wire, getting that circlip groove cut was a test of my patience! The smaller the work, the more my hands shake.

 

[Dhal22]

I like them big. Too big for electric but gas powered needs machined parts as well..

 

[Driveslayer45]

that is a great idea. i need to remember that the next time i bend a shaft vs replacing the motor