Electrathon America

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 2.

When we designed the car above, I put a student on a table with his legs sretched out straight and a board under his back. I propped the board up with books until he could easily see over his toes. Then I started taking measurements. I did a similar process with the orange car, but I propped up the "driver's" knees with a bar to simulate the front axle under his knees and then propped up his back until he could easily see over them. In both cases I did a quick diagram with measurements. Then it was time to start building. The next step is to acquire something to build with. Some of the well-healed teams in the Northeast use some pretty exotic materials in their builds like carbon fiber and Kevlar, but I'm on a budget here so we'll stay a bit more conventional. I made a trip to the local Lowe's and picked up some EMT conduit. I got four 10-foot pieces of 1/2 inch and two pieces of 3/4 inch. I also grabbed a roll of aluminum "kick panel" from the area where they have siding and porch screen stuff. The aluminum is .024" thick, 16 inches wide and 16 feet long. All together it was $45.

I did some poking around in my old files and came up with this diagram I sketched back when we built the car above. It obviously is not to scale and the human form is not reclined as much as the dimensions indicate, but it gave me some measurements to work from. The student I used as my “model” was 6'3" tall. Once we had his back supported at the desired angle, we started taking measurements. I measured from the bottom of his shoes to approximately where his tailbone would contact the table. I measured the height of the plywood at the top of his shoulders so I could make the seat back. I measured to the front of his shoulder so I would know how high to make the sides. I measured to the top of his head so I would know how high to make the roll bar. Etc, etc.

OK, the first step in construction is to make some preparation. As noted earlier, I already picked up the conduit for the frame. Next, we need a few tools; in addition to a welder and few other usual fabrication tools, we need a couple of conduit benders (1/2" and 3/4"), an ordinary framing square, a tape measure, and a tubing cutter. Also, not pictured, we'll need a chalk line, a combination square, and a half-sheet of plywood (scrap plywood is OK as long as it's flat). I began by splitting a sheet of 1/2" plywood down the center (24" x 96") and laying it across two tables. This would become my frame jig. Next, I struck a chalk line down the center. Using the chalk line as the center line of the vehicle, I used the tape measure and framing square to lay out some key points. Then I used a straight-edge and pencil to "connect the dots" and end up with a rough outline of the frame. I cut some small pieces of scrap wood to make "fixtures" or "stop-blocks" and screwed these to the plywood in some key locations. More precisely, I put the "outside" blocks right against the pencil lines and then used a piece of 1/2" conduit to locate the "inside blocks. Finally, I was able to start fitting and bending some conduit.

OK, notice in the 3rd pic above that I bent the front of the conduit so that the pieces will come together at the front. They will be positioned so that they come together and also turn slightly upward. I determined that to accommodate the shoulders of an average person, the width of the car needs to be 21 inches at the shoulders. On the original car, we tapered from the rear cross member forward. However, at the area of the driver's elbows the width has shrunk down to a little over 17 inches. That's fine for a driver that is of slender build, but from driving that car myself, I have determined that comfort would be improved if I maintain the 21 inch width at least to the area of the driver's elbows before beginning the taper. With that in mind, that is how I laid out the outline and set the stop-blocks on the plywood jig. With a very slight bend at the "elbow area", the conduit lays in the jig like it should. I used a piece of the 3/4" conduit and a couple of clamps to hold the pieces in place. This was not clamped tightly enough to damage the conduit, just tight enough to make sure they stayed flat on the jig while I did some welding. I then tack-welded the front of the conduits together and cut, fit, and tack-welded a crossmember where the back of the seat will be. At this point I also formed the main hoop of the roll cage from 3/4 inch conduit and tacked it in place. The crossmember and the bottom of the hoop converge at the same place. Bending the roll cage hoops is a challenge... I do it by bending the conduit a little, sliding it through the bender, bend a little more, repeat, repeat, until I get the shape I want.

https://view.officeapps.live.com/op/view.aspx?src=https://electrathonoftampabay.org/www/Documents/Jim%20Robinson%27s%20Build%20Process/Electrathon%20Build%20Thread%202.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 3.

In the first (top left) picture below you can see the main roll cage hoop propped up with the framing square and a couple of small blocks under it. You can also see that I have bent the bottom conduit ends upward. I will trim and shape these a little further later. After welding the roll cage hoop and crossmember as completely as I could with the frame still in the jig, I removed the whole assembly and used the jig again to shape the top rails for the frame from 1/2 inch conduit. Keeping in mind that I am working upside-down now, I bent the front similar to the bottom pieces, but left the ends somewhat longer. With the ends clamped together, I was able to mark where the second bends needed to be and bend the conduit to fit. Finally, I tack-welded the front ends together and tack-welded a temporary crossmember across the conduit a little forward of the "elbow area"

I should have mentioned before that welding galvanized metal can be hazardous to your health if you inhale the fumes. I'm not sure what gasses are generated, but it is my understanding they can make you quite sick and possibly cause nerve damage. I should have warned that welding this material (conduit) has to be done in a well ventilated area. I usually have a fan blowing toward the work to carry the fumes away.

After tack-welding the top frame tubes together at the front and with a temporary crossmember in place, I removed them from the frame jig. I put the bottom frame & roll cage hoop back in place on the jig and now I can fit the top section to the bottom. I set them together so all four frame tubes come together at the front. Then I trimmed the back end of the top tubes so that they intersect with the roll cage hoop 14 inches above the bottom. When I was satisfied with the fit, I tack-welded the ends together at the front and tacked the back of the tubes to the roll cage hoop. The temporary crossmember stays in place on the top tubes for now. I need to mention that conduit is easily notched or "fish-mouthed" with a pair of aviator tin snips.

For the next couple of steps I felt it was necessary to clamp the frame down firmly to the tables so that things would not move while being welded. I was able to clamp the rear of the bottom frame tubes and the frame jig down directly to the edge of the table. Up front, I used a scrap piece of lumber that reached across the table and clamped it at the sides. The next piece I fabricated was the piece that ties the roll cage hoop to the rear of the frame. I bent a simple half-rectangle from 1/2 inch conduit and fit it behind the roll cage hoop at the same height as the front tubes. I had to bend the rear upright ends inward to make everything come together. The pictures do a better job of explanation than my words. Once satisfied with the fit, I welded it in place.

https://view.officeapps.live.com/op...%20Build%20Thread%203.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 4.

Next step in my build was to complete the roll cage. All this requires is another hoop bent from 3/4 inch conduit to the same approximate radius as the first one. I trimmed and fit this one so it attaches to the top frame rail about half way between the main hoop and the rear of the frame. I also bent the little hoop for the headrest from 1/2 inch conduit and attached it to the upper rear crossmember. At the top, the roll cage hoops are about 4 inches apart and tied together with another piece of 3/4 conduit.

The following pictures contain a wealth of information, but I must apologize for them. I went to school on that particular day without my camera. When it came time to work on the car, I couldn't very well tell the kids "We can't do any work today because I don't have my camera". So, we proceeded with the day's activities and I had to take these pics the next day... What we're seeing in the first pic is the frame with the top & bottom center crossmembers and the vertical uprights in place. All those are in the vicinity of where the front axle will go. Notice that the top piece is arched slightly. This helps to hold the shape of the body later and will become the support for the steering shaft. Also visible are the diagonal aluminum side supports. In my previous car I made these from more conduit, but since they are always in tension, I have used aluminum this time. The 1/16 X 1 aluminum flat stock weighs about 1/3 of an equal length piece of 1/2" conduit. The second pic shows the seat-back supports and the temporary seat back made from 3/16” Luan plywood.

In order to put those aluminum supports in place I had to have something to attach them to. I got some #10 fender washers at the local hardware store and welded them in diagonally opposing corners. The rear ones are placed at the base of the roll cage hoop where it attaches to the lower frame tube (1st pic below); the forward ones are at the junction of the forward vertical member and the upper frame tube (2nd pic below). Aside from providing an attachment point for the aluminum strips, the washers also form gussets in those corners. To install the aluminum and get it tight, I needed to pre-stress the frame. To accomplish that, I placed a 3/16" thick strip of wood under the frame at the bottom seat crossmember (visible in the first and 3rd pic) and then clamped the frame down to the table on both ends. Next, I cut and drilled the aluminum to fit, riveted it in place with large-head 3/16" rivets. When I released the clamps, the frame sprung back to its original shape and pulled the aluminum tight.

https://view.officeapps.live.com/op...%20Build%20Thread%204.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 5.

Next on the agenda is to mount the rear "suspension". (I put it in quotation marks because this car really has no suspension; it is rigid.) The rear wheel is mounted using an ordinary bicycle front fork. In this case I am using the fork from a 26 inch beach cruiser, simply because that's what I had on hand.

I prepared the fork by opening the axle slots up with a file to accommodate a 14mm diameter bolt because the wheel I will eventually use here has a 14mm axle. Then I cut the neck off the fork with a hacksaw.

To mount the fork, I set the frame on blocks at the intended ride height. Then I put a 20 inch wheel in the fork and propped it up in its approximate position. I put a slight bend in a short piece of 3/4 inch conduit and then cut it to fit between the rear roll cage hoop and the top of the fork. It also connects with the top of the headrest hoop. With everything fit in place, I tack-welded the conduit piece in place.

Using a mix of tape measure, combination square, and "calibrated eyeball", I got the rear wheel and fork pretty well lined up and put a healthy tack-weld at the top of the fork. I then removed the wheel and hung a plumb bob from the center of the fork and used the tape measure to make sure the fork was centered and vertical. When I was satisfied with that, I then measured from each side of the fork to the center of the front of the frame. I was already really close on this, but I tweaked the fork until both measurements were exactly the same (as close as could be determined with a tape measure - less than 1/32" difference) and then added two more tack-welds at the top of the fork. Finally, I cut two lower struts from 1/2" conduit and connected the bottom of the fork to the frame at the lower corners. With the struts in place, I checked the measurements one more time and welded everything solid.

In the last pic above and below here, the center seat back support is visible (arrow). I added this because the motor I'm using (Briggs Etek) requires a face mount that must have a top mounting bolt. I will add the bracket later. If it was just a flat base type mount, I would have used an aluminum strip for the seat back support.

https://view.officeapps.live.com/op...%20Build%20Thread%205.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 6.

The next part of the build is probably the most difficult part - the front end. Up to now we've been putting pieces together to form the frame. Everything has been welded or riveted and, if it was a 32nd or even a 16th of an inch off, no big deal. The front end, however, includes the steering and we are now dealing with some moving parts that affect steering geometry and rolling friction.

To begin, I put the frame back on the jig and spaced the whole thing up off the table to the intended ride height. I then used a 20 inch wheel with a bolt through the center to determine where the spindle shafts and, therefore, the ends of the axle would need to be. The way this car is configured, the driver's legs will pass under the front axle. Because of that I had to keep the axle as high as possible in the frame. In order to keep the axle high enough but still get the ends low enough, the axle would need to rise in the center. I put a slight bend in the center of a 34 inch piece of 3/4" conduit, inserted it through the frame and clamped it in place. This would become the main axle tube. After centering it by measuring from both ends to the frame, I welded the tube in place.

The next thing I did was build a small fixture to hold my king pin bosses in place at the proper height and angle. The bosses are made from 1/2" O.D. 3/8" I.D. tubing that I got at ACE Hardware. The fixture was made from scrap 3/4" plywood. I tilted it in 7 degrees to give me a 7 degree king pin inclination. I also cut the blocks so the kingpin boss would be installed with 7 degrees of caster.

With a kingpin boss clamped in the fixture, I moved it into position and determined where I needed to notch the top of the axle tube. I notched the axle tube with tin snips and then tack-welded the kingpin boss in place. I repeated the proceedure on the opposite side and then welded them both completely.

To finish the axle, it needed to be braced. The front end of these cars sometimes take a beating from bouncing off of curbs, running over parking lot drain grates, and an occasional collision. To add the appropriate strength to this axle assembly I bent two pieces of 1/2" conduit to about 60 degrees and then trimmed them to fit between the lower part of the kingpin boss and the vertical frame member. I took care here to make both sides as identical as possible. When I was satisfied with the fit I welded both of them in place.

Horizontal bracing of the front axle is purely a matter of personal preference. The reason I don't put lateral bracing on the front axle is because, if it hits something hard enough to cause damage, I would rather just bend the axle tube than transfer the damage to the frame. Once during a race in my orange car (pictured previously), I was cut off going into a corner and simultaneously tangled with the other car and the curb. The left end of the axle was pushed back two inches, but the wheel was undamaged and I was still able to finish. Between the day's events, I was able to straighten the axle and went on to win the second event of the day! Had the axle been laterally braced, it could have caused damage to the frame that might have sidelined me for the rest of the day. As I said, it's a matter of personal preference, but Electrathon usually isn't as "rough and tumble" as Karts (I've raced those, too).

https://view.officeapps.live.com/op...%20Build%20Thread%206.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 7.

Having built the front axle, the next logical step is to fabricate some spindles. For the knuckles I used 3/16" x 1 1/4" flat steel. The first pieces I fabricated are the steering arms. These pieces also form the top piece of the spindle knuckle. No rocket science here, I merely drilled the appropriate holes and then cut & ground the pieces to the shape I wanted. The hole for the tie rod is 1/4", the hole for the king pin is 3/8", and the other holes are 1/2" and are just for reducing weight. Notice I bolted the pieces together for grinding. That way the two pieces are identical. The other pieces are pretty self explanatory. The long piece has a 1/2" hole near the bottom where the spindle shaft (a 1/2" x 5 1/2" bolt) will be welded later. The little piece is just the bottom piece of the knuckle.

To assemble the spindles, I cut a scrap piece of 2" x 2" lumber on the miter saw. I was careful to make sure the saw was squared so it would cut nice square ends. I then cut the wood 1/16" longer than the kingpin bosses on the axle (kingpin bosses are 3 3/4"; I cut the wood piece 3 13/16"). I bored a 3/8" hole through the wood so I could bolt the knuckle pieces in place and then positioned and secured the outer piece with a clamp. After welding the outside, I removed the knuckle assembly from the wood and welded the inside. I simply repeated the process (using the same wood block) for the other spindle knuckle being careful to arrange the pieces so it would make the opposite side

The wheels I am using on the front of this car had to be specially assembled for me. 20 inch wheels with hubs that accept disc brake rotors are almost non-existent. At the local bicycle store, the proprietor and I selected a mountain bike hub that has sealed bearings and disc rotor mounting holes. Then I picked out a double wall alloy rim and the bike shop guy called his supplier and ordered them for me. $85 per wheel and two days later I got these. The hole through the center of these is about a half millimeter larger than 3/4" (20 mm). The disc and brake caliper are not included in the $85 they are sold separately.

At the local ACE hardware store I found some bronze Oilite bushings that are 3/4" O.D. and 1/2" I.D. The perfect solution for putting 3/4" hole bearings on 1/2" diameter axles. I failed to take a pic of them separately, but the bronze shoulder is visible here behind the nut.

To weld the 5 ½” spindle bolts into the knuckles and assure that they are straight, I used a short piece of conduit as a sleeve and tightened the spindle nut firmly against it. Then I welded the head of the bolt to the back side of the knuckle. The sleeve not only assured that the bolt was installed straight, but also protected the bolt & threads from the welding spatter.

https://view.officeapps.live.com/op...%20Build%20Thread%207.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 8.

Steering is next. A lot of Electrathon cars have twin-lever steering because entry and exit of the car would be difficult or impossible with any type of steering wheel in the way. In this design, however, a steering "wheel" is not only possible, but preferred. It works just like the steering seen on most Go Karts; a shaft, "wheel", pittman arm, and tie rods.

The first step is to locate where the steering shaft will go. To do this, I used a piece of conduit about 4 feet long. I put one of my students in the car and determined the approximate height and angle needed for the shaft. Then with the long shaft propped in place with a piece of flat stock and a folded rag, I was able to tack-weld the upper sleeve in place.

Next, I fabricated the pittman arm from 3/16 x 1 1/4" flat steel. I have to admit here that I actually made this piece three times before I got it right. The one in the unassembled pic is the first one and it was too short. The second one was also just a bit too short. Finally, on the third try I got it long enough. I also cut the conduit shaft down to a useable length.

The tie rods are fabricated from 1/2" O.D. tubing (bought at ACE Hardware) with a 1/4-28 grade 8 bolt welded to the end. At this point, the pittman arm is still not welded to the shaft.

With the major components all fit, it only takes a couple more steps to finish the steering. I first welded the pittman arm to the steering shaft. I only welded it on the side away from the sleeve so that it won't grind into it and cause unnecessary wear and binding.

Next, I fabricated the "wheel" (actually more of a bar because of space limitations) from a piece of 3/4" conduit cut to 14 inches in length. I notched it in the center so that I could bend it about 10 degrees and welded it. This serves two purposes. First, it helps to keep the ends of the "wheel" inside the cowling when turning. Second and more importantly, it makes gripping it more comfortable. After climbing up on the table and slithering my fat self down into the chassis, I held the steering "wheel" where I felt it was comfortable and marked the location on the shaft. Then I climbed out, removed the steering shaft, cut it to the marked length, and welded the "wheel" to the steering shaft. Care must be taken here to make sure the "wheel" is perpendicular to the pittman arm.

Finally, I reassembled everything and then drilled a 1/8" hole horizontally through the shaft and secured it with a hitch pin (arrow)

Brakes are next! Electrathon rules state that brakes are required on at least two wheels on the same axle. On a tricycle car it is easy to use ordinary rim calipers on the rear wheels. It becomes a bit more difficult on a cycle car because there is no fork assembly or framework where a rim caliper can be mounted on the front wheels; the brakes must be mounted at the spindles. In the past we commonly used Arai drum brakes on these cars. Unfortunately, Arai stopped making those over a year ago and they are no longer available. The obvious alternative is some of the newer (and more effective) disc brakes...

After assembling the discs to the wheels and the wheels on the spindles, I held the brake calipers in place, one at a time, to determine what kind of brackets would be necessary. A little rummaging through the junk cabinet netted an 8" corner bracket that is made of 14 gauge steel - perfect!

The bodies of the calipers are cast in an offset configuration to accommodate the fork mount on a bicycle. Therefore, in order to get the calipers in their correct positions on opposite sides, the brackets are different. I started by making patterns from poster board. The one for the right side was easy and accomplished on the first try. The left one was somewhat more difficult; I configured and cut it out four times before I got it right...

Once the bracket patterns were transferred to the steel, holes drilled, and shapes cut out (with a hacksaw and grinder), I bolted them to the calipers. Next challenge was to hold them in place and mark their locations on the spindle knuckles. Once satisfied with my marks, I disassembled the calipers from the brackets and the wheels from the spindles. Then I was able to clamp the brackets in place according to the marks and weld them in place. Finally, I reassembled everything and checked for smooth operation.

https://view.officeapps.live.com/op...%20Build%20Thread%208.doc&wdOrigin=BROWSELINK
 

bob58o

SuckSqueezeBangBlow
Messages
9,594
Reaction score
1,482
Location
Chicago-town USA
Just started looking at this…
How do they determine what is “equivalent” to a gallon of gasoline?

Assuming $4 per gallon for gasoline and $0.125 for a KWH of electricity, I can get about 32kWH for the price of one gallon of gasoline. My 750w e-bike battery is 48V and 20 AH (call it 1kWH). My battery probably lasts 30 miles at 20-25 mph.

32x30 = 960
So on this e-bike, I get about 960 miles for the price of a gallon of gas.

About 40x the equivalent fuel efficiency (by price) of a car that gets 24mpg city.

I think small motorbikes (like Honda Trail 125cc) get close to 100 miles per gallon.
The e-bike is still 10x equivalent fuel efficiency (by price).
 
Last edited:

bob58o

SuckSqueezeBangBlow
Messages
9,594
Reaction score
1,482
Location
Chicago-town USA
“Thus, 1 gallon of gasoline generates the same 'heat energy' as 33.7 kilowatt-hoursof electricity. If an electric vehicle is able to travel 100 miles on 33.7 kWh of electricity (the energy equivalent of 1 gallon of gasoline), it would be rated with an MPG equivalency of 100 MPGe.”
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Hey Bob,

Yup, the numbers are pretty amazing :wai:

oops...almost forgot about this :innocent:

Part/page 9.

Well, it's finally on its own 3 wheels. Next up... motor mounts

OK, first step to mounting the motor is to mock it up in position. I am using a Briggs & Stratton Etek motor here (Yes, Briggs & Stratton makes electric motors!. After situating the motor where I wanted, I added two crossmembers in the frame to support it. The rear one had to be contoured slightly on the ends to get it back far enough.

After the crossmembers were welded in place, I next fabricated the bottom mounts from 18 gauge perforated angle. Yes, this lightweight stuff supports the motor just fine; electric motors don't vibrate like gasoline engines, so metal fatigue is not a problem. I cut these pieces so they are mirror images of each other, notched them to fit the crossmembers, and then folded the bottom edges upward at a 90 degree angle. The fold adds strength and also keeps the bottom edge from hanging below the frame. I mocked up the motor in place again with the mounts underneath to assure the fit and mark which holes would be used. While the motor was in place I fabricated a tab for the top mounting hole; it's a piece of 16 gauge steel, drilled, and a 5/16 -18 nut welded to it. Then I elongated 4 pairs of holes where the motor bolts down to allow for chain adjustment (I put a red outline around the elongated holes so they would show for the picture)

I mocked everything up again, this time with bolts in place. I squared everything up with a try-square and measuring tape, and tack-welded the mounts in place. Then I removed the motor and welded everything solid. Finally, I reinstalled the motor and bolted it down.

In order to use an electric motor, an electronic motor controller is necessary. Without some type of controller, the motor would either be full-on or off; there could be no intermediate speed, no smooth acceleration, no real control. A mechanical potentiometer big enough to handle the amperage of two Optima batteries in series would be HUGE and heavy. Electronic controllers do the same job, but are substantially smaller and lighter than a mechanical potentiometer. They use a very low power electronic circuit to control the main power circuit. Although controllers can get expensive, the one I am using here is a remanufactured Scott controller that I bought a few years ago for $160. Sometimes, used controllers can be had very inexpensively through golf cart service places. When they get “touchy” at low speeds they are removed and replaced (Little old ladies who play golf don’t like golf carts that have sudden or jerky starts.), but they may be fine for Electrathon.

I located the controller near the motor, but far enough away so if I ever throw a chain it won't be likely to whip the controller. Mounting it was simple; I just fabricated a couple of tabs that match the bolt holes on the controller and welded them to the rear crossmembers.

On the silver car and orange car pictured previously, I used 18 gauge perforated angle to make the battery trays. For this car I decided to try something different (and lighter?)..

I bought some 1/16" wall, 1" aluminum angle at the local ACE Hardware. I don't have access to a TIG welder, so I used 3/16" pop-rivets. I cut a piece of angle long enough to go around the perimeter of the battery bottom, allowing 1/4" clearance both directions, plus an extra inch for overlapping the ends. I drilled a 3/16" hole through the fillet of the angle where the bends would be and then made a cut from the edge of what would be the bottom to the hole (see pic). Then I made the bends in a vise with the bottoms of the corners and the ends overlapping. After checking and adjusting for square, I also riveted the bottom of all four corners.

I made eight mounting tabs (four for each tray) from 1/8" x 3/4" flat steel. I drilled and riveted the tabs to the battery trays and then welded the assemblies in place from the bottom of the chassis.

Because of the weight of the batteries, the bottoms of the side pods need additional support along the outside. In this case I used 1/8" steel round stock (welding rod) to make a pair of diagonal struts for each battery pod. The forward ones are welded to the outer bottom rail in front of the battery tray and to the top rail near the steering wheel crossmember. The rear ones are welded to the outer bottom rail behind the battery tray and to the main roll cage hoop.

https://view.officeapps.live.com/op...%20Build%20Thread%209.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 10.

To enclose the batteries inside the bodywork, I needed some type of framework to which I could attach the "skin". Some 1/2" conduit would work, but would be heavier than necessary to simply support the body panels. I chose instead to use something a little unconventional. At the local auto parts store I picked up two 6 ft. pieces of 3/8" steel fuel line tubing. It's extremely light, easy to bend, can be welded, and it's hollow so I can drill it for pop-rivets.

I bent the 3/8" fuel line to the same shape as the outer bottom rails and cut them to the same approximate length plus about 1 1/2" on each end. I used the leftover pieces to cut a pair of uprights for each side. The front pieces are sized so that, measured from the bottom of the battery tray, they are 9" tall (the overall height of the batteries with terminals in place + 1/4"). The rear ones are 3/8" taller simply to give the finished side pods a little tapered appearance.

Using a cadre of measuring tools and a lot of "calibrated eyeball", I located and welded the vertical pieces in place. Then, using some masking tape to help me hold the top tubes in place, I trimmed and fit the ends. Once satisfied with the overall fit, I welded them solidly in place.

I made the seat pan out of a piece of thin gauge aluminum diamond plate. I used this sturdy material because this piece supports a lot of weight when the driver is climbing in and out of the car. To lighten it a bit more, I cut a series of holes in it with a 1 7/8" hole saw. I attached this to the bottom of the frame with 3/16" pop-rivets spaced about 5" apart across the back and down both sides. I left the front edge unattached for now; it will be riveted simultaneously with the front floor pan.

The last little bit of fabrication is to weld in a couple of heavy duty washers for seat belt mounts (see arrows). I located these by climbing into the car one more time and marking the approximate location of my hips.

Finally, one can of Rustoleum gray auto primer and five cans of Krylon gloss white later, I have a completed frame ready for bodywork.

Next step: making and installing body panels. For this I am using aluminum "Kick Panel" material available at Lowe's and Home Depot. It is found in the area where they have the screen enclosure stuff for patios, etc. It is available in a dark brown satin finish or gloss white. The aluminum material is .024" thick, 16" wide and 16' long. I just went back for a second roll... I am using white; that's why I painted the frame white. I may give this car a different paint scheme in the future, but for now I'm sticking with the white.

Working with the bare frame simplifies making and installing some of the body panels. Before I put all the wheels and steering hardware back in place, I made and installed the front floor pan and the two long side panels. The floor pan was pretty straightforward; I simply cut a piece of aluminum to the measured length, laid it on the bottom of the frame, marked the edges with a washable marker, and cut to fit. I installed it with 1/8" pop-rivets 3 1/2" apart.

The side panels are not so easy because of the intricate shape. For these I made a pattern from poster board. I taped two sheets end-to-end and then cut them to 16" wide to replicate the size of the aluminum. Using masking tape as my "extra hands", I tried and trimmed the pattern until I was satisfied with the fit. When I got it to fit one side, I took it to the other side to see if it would fit there. There was only a slight difference in length at the very rearmost edge, probably caused by a small difference in the side pods somewhere; not bad for a hand-built structure!

I transferred the pattern to the aluminum with the washable marker and cut it out with tin snips. This time, I held the side panel in place with strips of duct tape. Although the picture shows masking tape, the darn stuff wouldn't hold long enough for me to get the rivets in place. I started at the front axle area and worked back, putting a 1/8" rivet about every 5 to 6 inches. No need to go crazy with the rivets here; these panels are more cosmetic than structural.
https://view.officeapps.live.com/op...20Build%20Thread%2010.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 11.

The nose is the next part I covered. I had to make the top nose section in two pieces; the aluminum I am using is only 16 inches wide, but the chassis is 21 inches at its widest point.

After locating the approximate point where the chassis gets too wide for the aluminum, I put a 1/16 x 1 aluminum support across for support. This piece is curved to match the steering support. Once it was riveted in place, I was able to fit the "skin" to the frame. After marking and trimming to fit, I riveted both pieces to the frame. The outer skin provides some structural rigidity to the nose, so I placed a rivet every 3 1/2 inches.

For the sides of the nose, I cut patterns. Actually, I re-cut the pattern I had used on the body sides (Hey, poster board ain't cheap!. Again, the same pattern fit both sides. After transferring the pattern to aluminum, I cut out the side pieces and riveted them on. Again, I placed the rivets 3 1/2" apart for structural strength.

The cowl piece was next. This turned out to be one of the most tedious pieces to make. I cut and re-cut the pattern several times before I got it to fit correctly. I wanted it to rise or flare upward so that it would be above the driver's hands on the steering wheel, but not so high that it would obscure forward vision. Also, the trailing edge had to be rolled for strength and safety.

After finally getting the pattern to fit the way I wanted, I transferred it to aluminum. When I cut it out I left an extra half inch along the back edge. I ran a couple of strips of masking tape along the back edge on what would be the outside to protect it from scratching. Then I used a large pair of lineman's pliers and a plastic mallet to roll the edge along the line traced from the pattern. I did not flatten the edge completely, but left it so the roll is about 3/16" thick.

Rolling the back edge left the ends curled somewhat, so I had to correct the shape a bit. I did that by persuading it with bare hands. I kept a rag laid across the nose while I was shaping the cowl, but I still managed to scratch the finish when riveting it in place...

The triangular shaped piece riveted at the front of the side pod is where the master power switch will go (arrow). I also made and riveted the headrest panel in place, but didn't take a picture. The bodywork is all done now except for the tops of the side pods. I will make those later.

Front end alignment is important on these cars to keep rolling friction to a minimum. To get the toe set correctly, I use this method that I borrowed from my stock car days. I made this pair of alignment boards in just a few minutes to use here, but they can be used on any car.

I began with some old shelving I scrounged from a renovation project here at school. This is 3/4" birch-faced plywood, but I could have used any flat material. I cut two rectangles the same size (11" x 24"). I screwed them together temporarily so I could cut them the same. I used a screw, string, and pencil to mark a half-circle on the top piece (Yes, I marked it twice. The first time wasn't big enough). After cutting the half-circle out on the band saw, I marked and bored two holes equal distance from the bottom corners. I used a 2" Forstner bit, but this could also be done with a hole saw. With all the cutting done, I removed the screws so I then had two identical pieces.

To set the toe, I put one of the boards against each front tire sidewall, secured with masking tape, and put a pair of identical tape measures through the holes. Now the toe could be set by comparing the readings on the tapes. I use 1/16" toe-in on this car. These boards also work on full-size cars; I have used this method on my ’31 Ford coupe hotrod and recently gave a set of these to a friend to use on his cars, also.

https://view.officeapps.live.com/op...20Build%20Thread%2011.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 12.

Now very close to being able to take this thing for a test-drive, I just need some circuitry for the motor and controller. The first part is mounting the main power switch through the triangular panel on the left side pod.

After that, I was able to run the battery cables. I didn't take any specific pics of this step because it's just a matter of cutting the cable (# 4 AWG) and soldering on the ends.

With the cables installed, next step is to install and wire the "dead man switch" and potentiometer. The "dead man switch" is required by Electrathon America. If the driver lets go of the controls, either deliberately or due to some sort of incident, all power to the motor is cut off. In this case, I used a little microswitch located on the left bar of the steering "wheel". When the driver's hand is on the controls, the upper part of the left forefinger holds the switch closed. If the driver's hand lets go of the steering, the controller cuts off power to the motor.

The throttle in these cars is a 5K ohm potentiometer which signals the controller. There are several options available for this including foot operated "pot box" assemblies and twist-grips similar to what is found on motorcycles. Everyone has their preferences, but I like a hand operated throttle. In Electrathon, consistency is important to battery life and having a throttle that the driver can "set it and leave it" helps to promote consistency. For this instance, I made a bracket from 1/16" wall 1" aluminum angle. I drilled and shaped the bracket and riveted it to the right bar of the steering "wheel". I positioned this so the potentiometer is accessible with the driver's right thumb. Roll the knob up to accelerate, down to decelerate.

If you remember from back near the beginning, I cut a "temporary" seat back from 1/4" luan plywood. It's light enough and rigid enough to be made "permanent" so here's what I did. First I riveted two strips of 1/16" x 1" aluminum across the seat back area (arrows). Next, I split the "temporary" seat back down the middle. After painting both halves (both for appearance and preservation), I hinged them together with duct tape. Now I can easily remove & replace it for access to the motor & controller.

In an Electrathon race, success and survival is all about battery life. In order to monitor how much juice you're tapping from the batteries, an ammeter is necessary. In this case I am using a digital unit. I made a little aluminum panel to hold it and riveted it under the cowl. The wiring feeds through a hole in the panel and into the back of the ammeter.

Except for the lack of a torso and some legs stuffed down in the nose, the second pic is pretty much the view from the cockpit.

OK, all major components are in place. It's time for a test drive. I took it outside and tooled it around the parking lot after school. I discovered very quickly that I had forgotten to tighten the nuts on the rear axle. Quickly fixed that... Otherwise, the test was without incident. The car is extremely smooth and quiet. This was Thursday evening (May 7th). Pic is the car as tested. Today (Friday) I forgot to take my camera. My kids and I did a little thrashing to get some last minute things buttoned up; I have a race tomorrow! We made the lids for the battery side pods, adjusted the brakes, made a seat pad from 1/2" foam sleeping bag pad, and installed an electronic bicycle speedometer. Hopefully, after tomorrow I will have some action photos to post here...

https://view.officeapps.live.com/op...20Build%20Thread%2012.doc&wdOrigin=BROWSELINK
 

Functional Artist

Well-known member
Messages
4,774
Reaction score
2,040
Location
Toledo, Ohio
Part/page 13.

SAM_3185 (1).JPGResults from May 9th: I'm sorry to say... I should have stayed home!.. Well, actually I'm glad I went, but the day was NOT a success from a competitive standpoint. It's always risky to take an untested vehicle to a race. Everything started off well. The car drew a LOT of attention…

I drew the last starting position and at the drop of the green flag I was trailing the field, waiting for them to string out. On the straights I was dialed up to pull 23 amps. Strangely, however, in the corners the ammeter was reading 38 - 39 amps when it should have been 25 - 27 amps. Seven minutes into the first race, my right front tire went flat! I limped to my pit, pulled the tire & tube off and discovered two cuts on the inside area of the tube. I wrapped a strip of duct tape around the rim, replaced the tire, installed a new tube, pumped it up and got back in the race. I lasted about another 6 minutes and the same tire went down again! Pulled the tire off again and discovered another cut on the inside near the rim.

Between races I went to a local bike shop and bought two more new tubes, one with Green Slime self sealing fluid in it. I chose to line up last again and got off to a good start. I had passed two other cars and was cruising smoothly, still wondering why the high current draw in the corners (hadn't had time to investigate because of tire woes) when, six minutes in, the right front tire went down again!!! I limped to my pit and removed the tire again. After 15 minutes of cleaning up Green Slime, I discovered that it was cut on the inside again. I put another layer of tape on the rim and re-installed the tire with my last new tube. By the time I got done, there were only a few minutes left, but I climbed into the car and made two more laps before the checkered flag flew. My total laps for the day: 42h (Should have been around 200 if I had finished both races).

Anyway, I know what the problem was and it was entirely my own fault. I am using double-wall rims on the front of this car. Getting tires on & off of double-wall rims is a real wrestling match and is further complicated by the rubber boot or rim strip. The spokes & nipples are recessed down inside holes in the second wall of the rim and I figured, since they are sort of out of the way, I could run with no boots on the rims... WRONG!! It was the edges of the holes in that second wall that were slicing through the tubes. Unfortunately, I went to Tampa and left the boots lying on my desk at school. My only recourse was the duct tape in my tool box and, as we now know, it's not heavy enough.

After the races I finally got to research the current draw problem in the corners. It appears that my front wheel bearings were "seating in" and allowing the wheels to move slightly on the spindles. This in turn caused the brakes to drag in the corners. I think my car would win an appearance contest pretty easily, but, as we all know in any kind of racing, looks don't make it go. The season is over now, so I have a few months to fix all the "bugs" and get ready for the next one. The good news is we stood the car on its nose on the scales and it weighs 102 pounds complete minus batteries.

Here are a couple of shots of me with the car so you all can get a better idea of the size of it. As you can see, the top of the roll cage is just below mid-thigh on me (I am just shy of 5'10"). When I am in the car, I am almost fully reclined. It's a close fit in there, but it's fairly comfortable. When I have my helmet on, my head is propped up just a bit more. If I were to change anything at all, I might raise the roll cage an inch just to make getting in and out with my helmet on easier. Overall, though, I am very pleased with the way it turned out.

For that last race, I was running out of time so I hurriedly made a couple of simple brackets from 1/16" x 1" aluminum to hold the rear view mirrors (required by the rules). Unfortunately, the brackets were too short and using the mirrors required me to raise my head up and lean to the side to see them... Instead of just making longer brackets and sticking the mirrors further out into the airstream, I decided it would be nice to make something a little more aerodynamic.

I began by making a pattern from poster board. Once again, I made the pattern more than once before I was satisfied with the shape and fit.. Next, I transferred the shape to a piece of aluminum. I traced the pattern once, then flipped it over for the second piece so they would be exactly opposite each other (one for each side).

To form the flanges on what would become the bottom of the mirror nacelles, I used a piece of hard wood with a straight edge and a rubber mallet.

I formed the shape of the aluminum pretty much by bare hands. The stuff bends pretty easily, so I just kept working it until I got the shape I wanted. When I was satisfied with the shape and had them as identical as I could get them with "calibrated eyeball", I made new mirror brackets form 1/16" x 1" flat aluminum. I replaced the old short brackets with the new longer ones (2" longer) and then installed the new nacelles in front of them. I think we can now call this car complete.

https://view.officeapps.live.com/op...20Build%20Thread%2013.doc&wdOrigin=BROWSELINK
SAM_3187 (1).JPG
SAM_3190 (1).JPG
 
Top