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So, here is the rough shaped shaft (steps 1 and 2) from above. I ended up buying a set of gage pins (another $135 into project) and now I can finally tell what is going on! Wish I had discovered gauge pins earlier in my prototyping journey. My motor rotor shaft after grinding down is 0.3055...

My 2 cents is that low boost is relatively low risk. However, the work, component cost, engineering, fabrication, motor, power system, control system, etc get to be quite costly even with lower requirements of boost. With my type of set up the cost difference between 2-4 psi and going for 4-6...

Good news and bad news… Bad news: My last motor extension shaft assembly still had too much runout (~0.014") once I figured out a way to measure it I had to cut my best extension shaft yet off the motor rotor. Good news: The ceramic bearing came in for my new design where it is mounted...

That is a brilliant and simple solution. I wish that I had thought of that myself. But, I appreciate you sharing the idea and will gladly swipe it and give it a try.

I think that I may have a viable extension shaft! I am basically using a modification of Matnrachs design with extension shaft attaching inside the motor housing and WBs manufacturing approach. The key was to make the hole last and use a 1/4” end mill mounted in my tool post as a boring bar. It...

In hopeful (naive? misplaced?) expectations of a making a viable extension shaft, I have decided that I will plan to balance the whole rotating assembly. So, to that end, I did a quick design and print of a shaft balancing apparatus. It holds the shaft assembly up at the ends in super low...

I was pondering some way to mathematically represent the overhang of different extension shaft configurations for comparison. I landed on the ratio of the outboard shaft extension (beyond the end bearing) to inboard shaft (supported between bearings). Below are 3 configurations, the first of...

I do like that tip and actually leave a 1/4" end mill in one of my lathe tool holders. I think I still struggle with the dimensions as I can't seem to get a good inside diameter measurement on small holes. And once I do I am relying on lathe micrometers, which aren't bad. Maybe I just need to...

In response to my bent motor shaft. I have decided to go into slice and dice mode, since I really don’t have much to lose as it is sunk cost. So, I took the rotor out of the motor to investigate further. I 3D printed a plastic sleeve and slipped it over the magnets to protect them. Then I dial...

I am definitely not there yet but have some learning from my build so far. Power: Seems like the battery discharges in the realm of 10X of which it can be charged. For instance 100 amps x 48 volts = 4,800 watts at low boost level. Where draw on car charging system maybe 40 amps x 12 v = 480...

My guess is either 1) was bad from the start or 2) there was axial thrust from the compressor and the rotating assembly stopped fast when the compressor contacted the turbo housing. I cant really recall as it was a while ago and did not seem catastrophic at the time but rather a metallic squeal...

Well after many iterations and chasing my tail, I think I have figured out the root of the problem. I used some decent steel stock and tried WBs method of making the hole last. I used a 1/4” end mill as a boring bar after drilling to 7.75mm since I did not have a small enough boring bar. It...

I heat shrunk the newest shaft and had similar results as before. Went on great with only 10 seconds of heating with torch and a good bond. BUT… runout went from 1.5 to 15 thousandths of an inch now that it is mounted to the motor shaft. Bummer… Next up grind it off. Then I will try WBs...

Well, I thought I had a good viable shaft per the above, but alas, it had run out in the realm of 14 thousandths of an inch once heat shrunk on the motor, so that one had to be removed as well. I believe that the inner and outer surfaces were not cylindrical with one another. Here are the next...

The next iteration was much better. I tried the method above with a slower pace, some breaks, some compressed air cooling, and lots of oil. The results were the best yet with just under 1.5 thousandths of an inch of run-out (and some of that was from my test pin). Sounds like the aggregation of...

Good thing I am learning driven!

I was excited to make another iteration of the extension shaft today with my newly set-up lathe. Every-time I seem to think this could be the one. All was looking better than ever… UNTIL I took out the live center. :( I could not believe it as the near-zero-run-out shaft that was spinning so...

I went way backwards yesterday on the lathe set up and struggled to get it even down to several thousandths of taper. After countless iterations, I finally honed in on it. The variable I had missed was how tight I was making the bolts that hold down the lathe. I was placing various shims under...

I just got a digital micrometer! So I measured the taper on a test piece. I am taking 3 measurements at three different spots on each end and averaging them. I was at about 2.1 thousandths out over about 2.5 inches. And keep in mind this is after I did my rough leveling last night, so before it...