Monday, September 10, 2007

Setback

I finished the subframe and got the motor properly aligned with the transmission (not so easy) and bolted everything down for a live test (without the driveshaft installed-- no driving through the shop wall). I rigged up a 300-volt DC power supply to run the motor drive, just to make sure it wouldn't complain about running off of batteries instead of its normal diet of 3-phase 240 Volt AC. It worked great. On to the powered test of the motor/transmission assembly. I ramped up the speed of the motor slowly, and everything was fine. I took things up a notch by quickly accelerating the motor, to simulate an actual load. Suddenly, the adaptor hub that I had spent a few evenings turning on the lathe twisted right in two. Oops. I had followed the design guidelines given by Lovejoy, the shaft locker supplier in machining the hub. The lock holding the transmission to the adaptor hub works by compressing a thin tubular section of the hub onto the shaft. I had my doubts that such a thin tube would be strong enough to carry the 150-220 ft-lbs (200-300 Nm) of torque Lovejoy advertised. It wasn't. Although, strictly, the shaft lock device was still securely in place, so I guess the book value was right. That's a little bit like building a ship in a bathtub, though...

Nevertheless, I shall continue! The next plan is to snag a splined hub from an old clutch disc, and attach that to the hub that is still locked on to the motor shaft, using bolts or perhaps my new bowhunting TIG welding skills.

Wednesday, September 5, 2007

It's a motor!


After quite a bit of sweating and head scratching, I got the motor into place.
Don't worry-- the C-clamps are temporary. The engine bay looks cavernous, but soon enough it will be crammed with batteries.

This style of design and fabrication is quite a change from my job, where everything gets designed using computer tools and precisely manufactured. This is more the "Orange County Choppers" school of metal work, only with a lot less swearing and throwing things. I sometimes wonder about those chopper shows on TV, whether they have a whole sweatshop full of 3D CAD guys sitting in a poorly lit room somewhere, swilling mountain dew and churning out chopper designs.

Sunday, September 2, 2007

Subframe

To make the motor, transmission, and car more or less one unit, I need to build a subframe. This will also serve as a platform for the front battery boxes. It was difficult to measure everything outside the car, so I decided to install the transmission, block it up to where it should be, and build the frame to it. Here's the transmission in place with the first cross member:
This is my first stab at TIG welding, so the welds aren't going to win any beauty contests. I'm happy with the overall result, though. Next, the top half of the subframe:

Mr Motor, meet Mr Transmission

I have been out of town for the last couple of weeks, so I was excited to work on the car all weekend. The shaft locks arrived while I was gone, so I set to work attaching the motor to the transmission. I had one small setback. The motor is a metric 112M size, which means that it is 112 mm from the base to the center of the shaft. It also should mean that it has a 28mm diameter shaft. For some reason, though, this one had an 1 1/8" shaft. This was a problem because the shaft lock I bought is 28mm. No worries, though. 28mm is smaller than 1 1/8", so I just turned the shaft down on the lathe.
This was good, as it gave me an excuse to take the motor apart.

Next, I test fit everything, and ran the motor for the first time attached to the transmission


Everything ran smoothly, so time to start putting it all in the car!