This is a school project in which I'm making a dual motor electric trike to carry one person. I've used many different metal working tools such as a lathe, milling machine, MIG welder, and plenty of hand tools.
Step 1: Main Frame Construction
Materials need for the main frame
- 35mm box section steel or similar (roughly 3 meters of the stuff)
- old BMX headtube
- steel rule
- tape measure
- hacksaw or electric auto one!
- engineer's square
- 200 amp MIG welder
- hand file (rounded and flat)
- electric grinder (speeds up filing and cleans up welds)
- various clamps and vices
1. Cut the box section steel to lengths of 1000mm (1 metre) for each piece
2. Front piece of steel is shape around radius of BMX headtube at a 10 degree angle of rake
3. Cut off headtube from BMX and file or grinder
4. File small 45 degree chamfers and the ends of the box section steel around the edges for better welds
5. Weld all these parts together as pictured
6. Grind on top of frame at the "t" join for a nice finish
7. BEFORE YOU WELD MAKE METAL SHINY BY FILING SO YOU HAVE A GOOD SURFACE
p.s you don't to follow the exact dimension, just my design has those
Step 2: Motor Mounts
- more box section
- angle iron that fits onto box section well
- all marking + measuring tools
- Clamps and Vice
- Milling machine with correct cutters
- Pillar drill (can use a hand drill but more difficult or impossible for one part of this)
1. Cut pieces to size (will tell sizes when finished by it will vary depending on your motor)
2. Mark out slots to be milled - make sure you have corresponding lines on both pieces for centering when welding
3. Clamp angle iron in milling machine
4. Mill slots (6mm slots here for my motor)
5. Do the same on the box section and go through the opposite side as well
6. Weld the 2 pieces together from the underneath (I needed a flush surface for my motor)
There will be a left and right version of this so just make 2 in opposite if you get me!
Step 3: Machining Wheel Sprockets
This part of the vehicle really depends on the sprockets your using. I worked out I needed a 5.2:1 ratio for my drivetrain. I had to achieve this ratio in just one step down. This wasn't possible due to the limited sprocket selection I had. So I ended up with an 8 tooth motor sprocket and a 40 tooth wheel sprocket. This is a 4.44:1 ratio but I thought that the motors would be able to handle the extra load so I went for it.
With my sprockets (mainly the wheel sprocket) I had to machine the bosses (the part of the sprocket that protrudes out). This requires:
- A centre lathe
- Measuring tools
- If possible Vernier Calipers (great for accurate measurements of diamters and bores)
The machining was needed because bolts were to be used for fixing to sprocket to the wheel and the boss was too large fit the bolt hole pattern in the wheel hub. You get me?
1. Mount sprocket into 3 jaw chuck in lathe
2. Turn the boss down to 40mm in diameter and 12.5mm in depth (was 25mm in depth and 60mm in diameter), keep checking the dimensions with the vernier calipers until you can make your final cut
3. Remember when facing off the face' of the sprocket the surface has got to be as smooth as possible.
For the motor sprockets it also depends on the sprockets your using, the motors and what sort of spindle the motor provides you.
On my motors their was a flattened egdge to it so I could use a grub screw and a thread in the sprocket hole to fix it to the spindle.
For this you need:
- Set of taps
- 10mm reaming tool
- Bench vice
- Drill bits
- Pillar drill
- Vice clamp for drill work
1. Tap the sprocket hole using the taps, firstly with the taper and then finish with plug (No pilot hole is required here
2. Then tap the hole for the grub screw (drill your pilot 1mm smaller than the tapped diameter)
Remember that clamping the motor sprockets are tricky and you should be able to use the teeth to hold the sprocket square in the clamp.
This is just what I did by the way. If you happen to make this yourself you might using keyed shafts, grub screws like mine, bolts, pins or anything else that lets you attach the sprockets.
I also had to make sleeve for the wheel bolts. These help space the wheel sprocket from the tyre to stop rubbing from the chain. These are simply round bar with a hole bored out from it. I cut the bar to length (8 in total, 50mm long) and then bored out the 8mm hole for the wheel bolts.
DRILLING HOLES FOR WHEEL BOLTS INTO WHEEL SPROCKETS:
You need a:
- pillar drill or a bench mounted hand drill
- 8mm drill bit (bolts for my wheels are that size)
- vice clamp for drilling
- centre punch
1. Mark out the holes with the scriber (I cheated and took apart my wheels so that I had one half of the wheel hub in which I used the bolts for marking out on my sprockets
2. Securely mount the sprocket with the vice clamp and then drill pilot holes
3. Drill holes with final size drill bit
SORRY THERE'S PICTURE FOR THE SPROCKET HOLES BUT ITS FAIRLY SIMPLE
Step 4: Welding the Motor Mounts to the Main Frame
For this disassemble the lovely chain drivetrain you've created.
For this you need:
- MIG welder
- Bench vice
- Right angled jig, this is comprised of two angle iron pieces fixed at a right angle
- G Clamps
- Combination Square
1. Position the main frame and drivetrain mount into the bench vice with the right angled welding jig, use the G clamps for clamping the jig to the frame and motor mounts.
2. Check for squareness with combination square
3. Tack weld the drivetrain mount then check for squareness with combination square. If not square use large hammer to correct
4. Fully weld each drivetrain mount (weld on the inside of the frame and the outside but not the top
5. After welding check again with the combination square. You'll notice that because of the heating process of the welding each motor mount will bend inwards by about 3-5 degrees. You can just get a nylon mallet and hit the motor mounts until they are square!
So check, check, check is what I say!
I'm sorry there are no pics for this stage, I had little time to do each stage as it was in school time with classes going on at the same time at some points!
Step 5: The Seat and Its Fixing
This part I will be explaining making the seat mount for a standard school chair. The chair had two tubes that went across the underneath that I could use for a simple mount to be welded to. The mount has several holes that bolts go through into the main frame for adjustment.
- Automatic Hacksaw/ normal hacksaw
- Steel Rule
- EngineerÃ¢â¬â¢s square
- Pillar drill/ bench mounted hand drill
- Centre punch
- Movable vice
- Drill bits
- Ball pein hammer
- MIG welder
- Small G clamps
- Bench vice
- Welding equipment
1. Mark out length angle iron according to your chair with scriber and measurement tools
2. Cut with hacksaw in the bench vice
3. File off burring for good finish and for no sharp edges
4. Mark out hole destinations for the bolts that keep the seat coming off the trike with measurement tools and centre punch.
5. Mount in vice clamps and drill out required holes with smaller pilot holes for accuracy. Then drill out fully.
6. The hard bit is getting the holes aligned with the holes that will be drilled in the main frame tube. Again these need to be measured and centre punch carefully, pilot holed then drilled fully. Test the mount in the frame and see if the holes work with the bolts. If its hard getting them DON'T wack them in with a hammer. Use a round file to adjust the holes so that you can slide the bolts in nicely without ruining the threads!
7. The mount needs to be welded to the bottom of the seat. Use your head and get clamp the mount to the seat for welding. Tack weld then fully weld the mount, CHECK that it still fits when you've tacked welded. ALSO before welding make sure any paint on the seat tubes is filed/ sanded off for a neater weld.
Step 6: Battery Holder
The battery holder idea came from the workshop technician at my school. Its just angle iron bent at right angles and welded shut.
- All measuring tools, scriber, combination square etc blaady bla
- MIG welder
- Hack saw, auto hackkereresaw
- Files/ Angle grinder
- Clamps and Bench vice
- Nylon mallet for bending
- Mole grips
The length of the angle iron depends on the batteries you use and this how I made mine-----
1. Work out how much angle iron you need plus bending allowances, make sure you choose steel that is isn't too thicker gauge otherwise its going to be hard to bend manually
2. Mark out all the lines where it will bent
3. Mark out using the combination square the sections that will be cut out to accommodate the bends, the combination has the 45 degree angle you want to get on the angle iron
4. Cut away and be careful about cutting inside and out of lines for the accuracy
5. Get the angle in the bench vice and bend around the lines you have made using the nylon mallet, perhaps try bending the same spare angle to see how much length you loose after it has been bent?
5. Make sure everything is square. I used a flat sheet of wood to work out what needed to be adjusted
6. Now use the mole grips to clamp the edges of the bends and tack weld. Check everything and then fully weld, WELD UNDERNEATH NOT ON TOP
7. Spruce it up and angle grind the welded off the angle and voila you have a battery holder to be welded behind the seat on the main frame.
ONe more thing, the angle iron i bent into shape had an extra piece cut to complete a rectangle but if you can work out a rectangle with all the bends with ONE piece then thats even cooler!
Step 7: Foot Plates/ Holders/ Pedals Whatever!
My foot pedals were quite poor and were made at the last minute and If I had more time I would definately make them more elegant and safe.
They are just two pieces of flat bar bent at appropriate angles then welded together to the main frame, see the final pictures to see what I mean!
Step 8: Electronics
This part of the project was a strange mixture of quality and last minute bodging.
- I used two 12v 32amp batteries
- A 75amp 24V speed controller made by 4QD in England- quite pricey but really reliable
- 5 LED battery condition meter
- Plunger pot for throttle
- Lots of cable
- Connectors for batteries
- Two 24v 300W DC motors
The picture for this step show the basic set up, and is not a circuit diagram.
4QD's site has extensive information on electric vehicles and how to work out battery, motor and speed controller configurations.
The choice of my configuration was analytically chosen from other electric vehicles like the Built For Fun Racer as these had the similar speed and weight I had in mind. This guy has indirectly help me with this project and his site also has plenty of information and plans too.
Step 9: Finished Trike
Thanks for looking,
I might be adding slightly more detail on the electronics and where to go for parts but in the mean time I thought was ok as it is!