Electric Mountainboard Detailed Build Instructions

I finally bought a second motor so I documented my build this time.

 

Here’s a parts list for a 1 motor build (double the counts for a 2 motor build which is WAY better)

Parts

• 3D Printed ‘Wheel Insert Inside‘ at 90% infill (PLA or ABS)
• 3D Printed ‘Wheel Insert Outside‘ at 90% infill (PLA or ABS)
• 3D Printed ‘Motor Mount‘ Left or Right depending on which side you are mounting. 90% infill ABS has worked best for me.
• 47 Tooth Sprocket
• 11 Tooth Sprocket
• #25 Chain
• #25 Chain Master Link
• Hobby King 150A Car ESC (Or similar ESC)
• ESC Programmer
• Turnigy SK3 213kv Motor (Along with the mounting plate and bolts that come with it)
• MBS Atom 90 Board
• Kenda K909 Tires
• Battery Box
• Turnigy Watt Meter
• Couples meters of black and red 12 AWG Silicon Wiring
• Bunch of male and female XT60 Connectors
• HXT 4mm Gold Connectors
• Y Servo Lead (Only if you have 2 motors)
• (3) 1/4-20 by 1/2″ long bolts
• (3) 1/4-20 nuts
• (6) 10-24 by 5/8″ bolts
• (6) 10-24 nuts
• (1) M8 x 30 (or 35) bolt

Other Parts

• Batteries
• Remote Control
• Charges and power supplies

See this post for details on batteries and chargers

Tools

• Chain Breaker
• 6mm Hex Key
• 5mm Hex Key
• 3mm Hex Key
• 3/32″ Hex Key
• Cordless Drill
• #10 Drill Bit
• #12 Drill Bit
• Letter ‘O’ Drill Bit
• Phillips Screwdriver
• 14mm Wrench
• 3/8″ Wrench
• 7/16″ Wrench
• Thread Locker

I’ve now setup an online shop so I can 3D print the parts for you if you don’t have a printer. You can get a quote here by uploading the linked files from above.

 

Step By Step Build Instructions

Step 1

Insert the 10-24 nuts into the slots in the ‘Wheel Insert Inside’. They should be a pretty tight fit. You might have the file out the slots a little to get them in.

 

Step 2

Insert the 10-24 bolts to make sure everything lines up.

 

Step 3

Also insert the 1/4-20 Nuts into the part. They should press right in.

 

Step 4

Remove the wheel from your board which you will be mounting the motor to. Now slip in the ‘Wheel Insert Inside’ into the back of the wheel. Making sure that the valve stem is coming out the front, and the notch in the part lines up with the valve stem. See the picture.

 

Step 5

Now slip the ‘Wheel Insert Outside’ into the wheel. Put the 10-24 bolts into the holes and tighten them down snug with your 3mm allen wrench. Don’t tighten them like a daemon. It’s just plastic remember. Oh and don’t drop this part and chip it like I did 🙂

 

Step 6

Next you’ll be bolting the 47 tooth sprocket onto the ‘Wheel Insert Inside’. Line up the sprocket on the part, and bolt her on. You should probably use a little thread locker on these bolts. (Pro tip: tighten the bolts so that the flat sides of the bolt head are tangent to the center of the circle. Otherwise they will hit your axle later)

 

Step 7

Find the little screws and the aluminum plate that came with the motor. Test the fit first, then definitely add some thread lock to the screws and bolt the plate securely to the motor with your screwdriver.

 

Step 8

This next step is probably a bit controversial. But all I have is 10-24 bolts so next I drill out the holes on the mounting plate. They are probably M4 or something but I don’t mind drilling them out a hair. So take your #12 drill bit to the holes on the plate so that the 10-24 bolts fit nicely.

 

Step 9

Drill out the slots on the ‘Motor Mount’. ABS shrinks a little so drill these out with a #10 drill to give a good fit for the 10-24 bolts.

 

Step 10

Place the motor assembly on the mount. Making sure that the motor wires are parallel to the M8 bolt. Pointing towards to top right of the picture below. Insert the 10-24 bolts through the aluminum motor plate and 10-24 nuts to the other side. Slide everything up and down a couple times to make sure it will move. It should be pretty tight to move. Also, press in your M8 bolt into the slot.

 

Step 11

Check to see if your 11 tooth sprocket fits onto your motor shaft. If it doesn’t, you’ll want to drill out the sprocket just a hair. Clamp the sprocket in a vise, and drill it out with your letter ‘O’ bit. (Pro tip: remove the set screws in the sprocket to avoid them vibrating loose when drilling)

 

Step 12

Slip the sprocket onto the motor shaft and gently tighten the set screws with the 3/32″ Allen key. You’ll be adjusting the position of the sprocket on the shaft shortly.

 

Step 13

Attach the motor assembly to your axle by threading the M8 bolt into the axle hole. It should be pretty stiff the last 1/4″ or so. As such you’ll probably need the help of a box end wrench or cheater pipe to give your leverage to tighten the bolt. There is a little rotation in the motor mount so hold it square to the axle while tightening.

 

Step 14

Put the wheel on the axle and tighten down the axle nut. Now you’ll align your 11 tooth sprocket to the 47 tooth sprocket. Loosen the set screws on the 11 tooth sprocket, line it up and tighten back down.  (Pro tip: spin your wheel a little here. If the bolts holding the 47 tooth sprocket hit your axle, rotate them like you should have done above. If they still hit, space the motor out with a washer.)

You absolutely, positively need thread lock on these set screws! I’ve had major problems with parts flying off when I didn’t use thread lock. Remove the motor if your allen key is too short while everything is mounted. Add plenty of thread lock and secure everything very well.

 

 

Step 15

Onto the chain. Count out 54 of the little chain axles and punch out the 54th one with your chain breaker. Count my picture below if you are paranoid like me. Double and triple check this number. You get one shot. No pressure 🙂

 

Step 16

Take off the clip and the one side of the master chain link. Slip it into your chain. Put the other side back on. Put the clip over one post, then use pliers or some black magic tool that I don’t know about to push the clip over the second post.

 

Step 17

Put the chain on the 47 tooth sprocket and be sure that the clip part of the master chain link is away from the wheel so it doesn’t rub. This is crucial, Don’t skip it!

 

Step 18

Bolt your motor assembly back onto the axle, slide the wheel onto the axle, and use whatever trickery you can to get the chain around both sprockets.

 

Step 19

You probably don’t have 4 hands, so solicit some help to tension the chain.  The best option seems to be tightening the chain as much as you can. This will induce extra coasting drag but it seems to help with startup cogging. Do a test by sliding the motor along the slots to get a feel for the force required. Also rotate the wheel to make sure everything is working and not out of round. Once you are satisfied, add thread lock to the bolts holding the motor on and tighten down fairly hard. You don’t want this sliding out of tension while riding.

 

Congrats! You’re half way there! Rinse and repeat for a 2 motor build which is WAY funner to ride!

 

Step 20

Decide where you are going to mount your ESCs. Right at the end of the board is probably as good as any.

 

 

Step 21

Determine your wire lengths from your ESC to your motors. I decided to trim down the motor wires a bit, since I didn’t want them flexing much.  Cut the wires and solder bullet connects back on. To solder this wire you’ll need to crank up your iron. Mine maxed out at 480℃ and this worked alright.

Strip the ends of the wires. Jut your 4mm bullet connector housings in half and place the ‘fat’ ones over the wires.

Tin the wires very well! Your motor won’t even spin if you don’t get a good solder joint here.

 

Fill up the bullet connector with a fair amount of solder.

 

Heat up the solder and put on the wire. Reheat everything to make sure it flows good. 

 

 

Step 22

Carefully slide the red housing up over the gold connector. I can never seem to get them over all the way, as they should ‘click’ in really nicely, but oh well.  Now solder the other bullet (female) with the skinny red housing onto the ESC wires in the same way. Connect the bullets and add some expanded mesh to make it look nice.

 

Step 23

Secure the ESCs and their switches on your board. VHB foam tape, hot glue, or the 3D Printed mount than I plan I designing soon. Also secure the radio receiver.

 

Step 24

Bolt your battery box to your board with some 1/4 – 20 bolts and nuts. Center the box over the board, and drill through the holes the are already in the board.

Step 25

Attach your Watt Meter to your board. I decided on some zip ties between the connectors and through some holes I drilled in the lid of the box. This makes it easy to move to other projects.

 

Step 26

Make your battery wiring harness. Cut your 12 AWG wire and solder into XT60 connects and then heat shrink the connection. My harness connects 2 sets of batteries in series, and then those two sets in parallel. This is for LiFePo4 Batteries – 2 4s 8400 mAh and 2 2s 8400 mAh wired as a 6s 16,800 mAh.  So I have a 4s and 2s as series. And then those in parallel with the other set. This all depends on what batteries you choose obviously so build accordingly. Just know that the ESC is rated for 6S LiPo max so don’t wire too many in series 🙂

You’ll also need another parallel harness to connect your ESCs into your battery pack is you have a 2 motor build.  I have my wires running over the top of the rear binding through some expanded mesh.

 

 

Step 27

You might need to bind your radio to your receiver. I’m can’t remember for sure if it came bound from the factory or not but the process isn’t hard. This video should help you out.

Calibrating your ESCs. This can be kind of tricky. I do one ESC at a time. I have no idea if you can do multiple at a time. Reading the instructions that came with the ESC gives you the idea but I found that reversing the throttle like it said gave, surprise, reversed throttle response. So don’t do that haha. The basic idea though is to connect your ESC to your receiver. Connect your battery pack to your ESC. Hold the little red button next to the ESC switch. Turn on the switch. Release the red button after the light goes dim. Then pull the throttle on your radio. Wait for a beep. Push reverse on your radio. Wait for a beep. Throttle idle and wait for a couple beeps. I had to try a couple times until I heard all the beeps correctly.

 

Step 28

Connect your ESCs through your Y servo lead and cut one of the red wires on the Y lead so your aren’t feeding 2 BEC’s together (I would probably work without cutting but I’m not risking my $70 speed controllers haha)

 

Done!

Ride and share your experiences in the comments below or post a video on YouTube!