Miles and Tyler - I'll check into those angle measurers. They look pretty inexpensive! That's always good.
New Year, new update. This has been a productive past couple of days in spite of a few setbacks. I recently connected the high-current shunt resistor (rated at 100 A) in line with the negative capacitor terminal to the Kelly controller:
Now, once I put in its correct resistance value into Cycle Analyst, I will be monitoring accurately-measured amps and power during operation. During another road test climbing hills and such, I had another axle spinout. As some people here already know, the NineContinent BLDC motor (http://www.ebikes.ca/store/store_nc.php
) is very "torquey," which I love, as that's the best thing for a start-stop type of bike, but it has a very small axle - a 12 mm threaded bolt with the usual 10 mm separated flats milled into it (http://www.ebikes.ca/store/diagrams/MNCF.PDF
). This is a great pain. A torque arm is a must, of course, but my application (throttling and regen braking) causes torquing in two different directions. Here is my junk heap:
A: Torque washer supplied with NineContinent kit. Its tolerances were fairly tight, but it was not up to the task.
B: I had higher hopes for the AmpedBikes arms, which I used together, one to resist pulling and one to resist pushing. Unfortunately, even these had a sub-par fit with the axle's flats. Even a little wiggle room was opening the door to failure.
C: I took a bar of steel (3/16", or 4.7 mm thick) and milled my own slot into it at the angle I required, using a hand file for a perfect slot diameter. The steel wasn't strong enough as you can see.
This last failure really got to me because it yanked the hall sensor wires and I had to disassemble the hub motor to get things right again. I took some time and came up with a plan to use the leftover steel bar to make a compound torque arm. Here's the raw stock:
Now, I was going to essentially bolt two flat edges of this steel, which is springy but not as hard as the axle's steel, and apply so much force that it couldn't possibly escape. I should have taken pictures as the machining proceeded but I was moving fast yesterday. Here's the AutoCad drawing:
The bolts go on either side of the axle, and are 5/16" in diameter (strong). Once the bar was milled down to the right width (0.45" or about 11 mm) and the holes were drilled, I was able to fabricate the longer piece with angled grooves at the top to hold the stainless steel worm clamp. The long arm was first twisted 90 degrees about the Z axis (out of plane) and then bent back to align with the fork. The grooves were aligned with the fork's tube, and I pressed a piece of aluminum as a spacer between the steel and the fork as I tightened the worm clamp. Here's the result:
and a closer view:
It is an extremely tight fit, and I have lots of force applied axially (by the axle nut) and radially (by my twin steel bolts) on the axle. It is not going anywhere. Best of all, the worm clamp holds the arm in place by preventing pulling and pushing (from throttling and braking, respectively).
The day may come when the torque arms are "built-in" to the hub motors, but until then there is always brute force.
Next job: calibrate the current readout and find out regen power and current for downhill coasting and various generator loads while pedaling on a level street. Before the axle issues above, I did pedal around for a while and raise my capacitor voltage from 40 to 48 V. Once I can read currents and get elevation changes, the data will have more meaning.