Rotor removal, and complete disassembly

So, last time I had a functioning gear-train, I just needed to disassemble everything in order to replace the outer housing.  As I was putting things together, I realized that several custom fixtures would likely be needed in order to disassemble various parts cleanly.  Here, I made a giant 3D printed cylinder that the front housing and planet output would bolt to, and then the central shaft could be pressed out.

Rotor removal fixture
Rotor removal fixture

I somewhat skimped on the printing… even at 25% infill it took something like 14 hours, however the shaft should be relatively easy to extract since it is only held via a mild press fit with the output shaft bearing.  Or at least, it would have been had my mild press fit not ended up being tighter than desired, and had retaining compound not seeped over there.

My first attempt at removal just resulted in my carefully constructed fixture delaminating and the entire planet output and output bearing pushing into the assembly.  The shaft didn’t budge at all on the shaft output bearing.  Then, rather than wait for an even longer print, I installed all the washers on each of the bolts to better distribute the load across the fixture.  At that point, removal was accomplished…. kinda.  The fixture didn’t fail this time, but the planet input in the gearbox shredded.  Fortunately, that was enough to remove the rotor.  I could just print a new planet input, and toss the shaft which now appeared very well welded to its bearing.

Output shaft and bearing
Output shaft and bearing… note the green retaining compound everywhere

 

Rest of the disassembly

At this point, the rotor was removed from the stator, but there was still a fractional planet input attached to it, with the planet input bearing very securely fastened to the sun gear holder, and the rotor bearing, even more securely fastened to the sun gear holder.

First, I shredded the planet input with a pair of pliers.

dsc_2066
Planet input, er… disassembled

Then, I was able to get the input bearing off by cooling down the sun gear holder with the compressed air again.

However, the rotor bearing was too well pressed on to achieve that.  So I ground it off with a cutoff wheel, after trying a few other things first.  At this point, I was finally able to remove the sun gear holder from the rotor, and call my disassembly, as it were, complete!

Rotor bearing removed
Rotor bearing removed

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