Motor Mount Mishap

After countless paper and wooden templates to get the motor mount shapes and hole patterns just right, it was time to give it a shot on the real stuff. I ordered a chunk of 3/8" aluminum plate. Using the CAD drawings, one of the guys at work helped me cut the basic profiles on the CNC Plasma cutter. I was totally stoked looking at this complex geometry that took about 60 seconds to cut out.

Unfortunately, my elation was short lived. Several edges of the pattern were severely tapered, so even though the shape was perfect on one side, it was off by almost an 1/8" on the other side. I knew the shape cut by the plasma would be a little rough and had adjusted tolerances accordingly, but it hadn't occurred to me that the plasma would cut at an angle. It's possible something needs to be fine tuned. If that's the best plasma can do, I may need to rethink the manufacturing process.

Once the outer and inner profiles are cut correctly, I will use a mill to precisely drill the mounting holes for the motor and frame. Just for kicks on this piece though, I drilled the mouting holes using a paper pattern as a guide. Of course the holes for the motor didn't quite match up, so all I could do was bolt the bracket to the frame to see if it's close.

A little dissapointing, but not too bad for the first go round.

Re-assembly Begins

I've been asked why bother to strip everything off the bike and go throught the tedious work of cleaning all the little pieces. First, I'm anal retentive and have to. Second, there's no other way to know what's missing, worn out or broken on a 20 year old bike.



I cleaned all the pieces of the rear suspension and put it back together. Initially I thought a spacer was missing on the linkage lever. Turns out it was assmbled incorrectly, and judging by the wear in mating aluminum pieces, been that way for a while. You can see how much more of the left spacer is exposed. While not catastrophic at this point, addtional wear could definately be a problem.





I have gone through several iterations on the wood patterns for the motor mounst and got the design close. I'm confident in the hole locations for the motor, but not too sure with the bracket locations on the frame. I needed a more accurate template to work with. The cheap solution was a piece of 3/8" x 1" aluminum bar with a printout of the only the frame hole pattern pasted on. After a couple of more tweaks, I should be ready to cut the actual 3/8" plate.

Spring Break

Due to comittments with our local Little League Baseball program, I will not have much time to spend on El Gixxer until summer.

I've done several more wood patterns for the motor mounts, tweaking various features. The latest version uses slightly bigger hoop to go around the right end of the motor (actually closer to the middle). The loop will be cut and some angle sections added to make a clamping mechanism.

I did have the opportunity to read "Powering the Future" by Tom Koppel. It's the story of the Ballard Fuel cell, and at the time it was written (circa 1999) the Fuel Cell was hailed as a revolution in automotive power. Although still viable, the infrastructure for Hydrogen or Methane to power the fuel cells is lacking and killed the momentum behind it. It's a powerful lesson to those of us that think EV's are ready to take on the world.

Measure Twice, Cut Once

I've been unable to focus on anything else but figuring out how to secure the right side of the motor. My preference is to use the same material that I use for the left mounting plate, 3/8" aluminum. The first trick is that bracket has to be two pieces or have notches for the pole screws so it can be slid on from the left. The other gotcha is there has to be some clamping mechanism to secure the motor.


I came up with this basic design a few days ago, but dismissed it because two 3/8" brackets will be fine to resist motor torque and vertical/hoizontal loading from the chain tension. But loads parallel to the shaft need something else. It came to me this morning, add an angle bracket and use the mounting holes in the case. (edit one year later:  no additional pieces needed, the dual bracket arrangement is plenty strong with regards to axial loads.)

I was so jazzed at having a solution, I cranked out the template to make the wood prototype. I also tweaked the geometry on the left bracket, thinking I could cut them both and have the wood parts done. Haste makes waste...

I neglected to check if I had enough RotoZip bits
and busted my last one starting the new bracket. I did manage to cut out a sloppy version of the left bracket, so at least I could get it fitted. Wrong-O! In adjusting the bolt pattern location, I appearantly changed the bolt circle diameter, making that version completely worthless. The only bright side of these wasted efforts is that it's only wood, not the actual 3/8" Aluminum.

Motor Mounting v1.01

When I actually positioned the motor inside the frame, I could see that my earlier ideas for mounting the motor were not feasible. The motor is offset much further to the right side of the frame than I had envisioned. I will have to go with a face mounted bracket on the left side, and some type of clamp or belly bracket on the right half of the case.

After some careful measurements, I came up with a couple of designs. I'm pretty sure of the general design of the face bracket, but still working on ideas for the right side. I printed out a full scale drawing of the face bracket and glued it to a piece of 3/8" plywood. Using a Roto-Zip, drill and sand paper I followed the lines on the drawing.

Looking at the wood bracket mounted to the motor and the frame, it almost looks ready to use. But a second look shows some flaws. The orientation of the face bolts is going to interfere with the chain, since there is only about 1-3/8" clearance between the face plate and the frame. I will need to rotate the bolt pattern so one of the bolt heads is between the loop of chain. The other probem is the verticle position of the motor shaft relative to the swingarm pivot. The motor needs to go about 1/4" higher so the chain can be vertically centered on the swing arm.

Another thing that is obvious is that wood is not the ideal choice for the actual bracket. The weight of the motor twists the wood like its made of rubber. Fortunately, the final version will be made from 3/8" aluminum plate.

While I was making a mess in the garage, I decided to to cut the bottom out of the gas tank. This frees up some space for mounting electric compents and saves some weight. After breaking a few bits on the RotoZip I switched to the Dremel using little cut-off discs. While effective, the Dremel was excruciatingly slow, but the end result was pretty clean. Cutting out the fuel tank was almost cathartic. It's like I was setting the bike free from slavery to big oil.

Run El Gixxer, be free!!

More Motor Mania

My wife says I'm "like a kid sometimes". I will not deny it. The motor arrived from D&D Motor Systems (http://www.ddmotorsystems.com ) and it was just like Christmas for me.

I threw the motor on the scale and it weighed in at a whopping 64.5 lbs. with the factory supplied mounting bracket.

I laid the motor inside the frame, just to get a feel for placement. It's going to stick out quite a ways on the right side of the frame. Fortunately it's a good looking piece of hardware.

Motor Madness

I've finally comitted to a motor: D&D ES-15A-6. This motor is heavier (62lbs), a little more expensive and much larger (~12.5" long) than the Etek-RT that I was originally thinking of using. I'm sure the Etek would have done the job, but in the end D&D's reputation for quality & customer support was the deciding factor.

If you have done any browsing of EV projects, you know it's fairly common to have problems with ordering parts from the cheapest source. I've spent enough time in the manufacturing arena to know some of the pitfalls in supplier selection. Up front cost is only part of the equation.

With the motor specified (and on it's way!!) I'd better get serious and figure out how to mount it. I see a lot of guys use the NEMA face mount by welding a plate to the frame, but that is not going to work on El Gixxer. Welding is not an option for this project, so the trick for me is using the existing rear motor mounts on the frame.

One advantage the D&D has over cheaper motors is that it can be mounted using the case as a structural member. The motor even comes with case bracket for mounting on flat surfaces. My idea is to use some 1.5" x .75" aluminum stock to make a couple of mouting struts. Once the motor arrives, I will make a wood model to try it out.