My first (and second...oops) electric longboard build log

[AndyPG]

What great projects electric skateboards are! They’ve got everything a basic, or experienced, tinkerer could want. Especially if you build your own deck like I did, badly…more on that later.

This site and all the information within has been a great help so thanks to everyone who has posted in order to help us new comers get through.

My board is currently, shall we say, at a prototype 2 stage.

I’ve got plenty of pictures and information so I’ll upload it in chunks over the next few days to create a blog that I hope comes in useful for others.

My methods and ideas are a mixture of old, new and what I thought was new but was actually old.

So, after a week of research I made up my mind to build a cheap,DIY Boostedboard shaped electric longboard. I’m even going to laminate by own deck…well how hard can it be?

I had enough 3.6mm thick general construction plywood to make a 4 layer laminate deck. This ply was absolutely not strong enough in the end but you live and learn. I PVA glued the laminates together and left it clamped in an improvised jig to create a slight concave across the width. 2 days later, I cut it to shape and took some admiring pictures.

Thanks for reading. Time for tea (takeaway) More soon.

[AndyPG]

Right, onward… Now some hardware.

I’ve been into electric model aircraft for some years and so I’m well familiar with the likes of Hobbyking and Turnigy. When I saw that the Turnigy SK3 series of motors are used for skateboard builds, my mind was made up. After lots of research I eventually decided on the 213kv 6364 motor.

What a beautiful lump of engineering and only £60/£70. (Yeh, things can cost a bit more here in the UK)

I’m not concerned with the stiff phase wires or the lack of a key way. I’ll sort it.

Next the wheels. If I’m to build a Boostedboard shaped object, it will need the right wheels even if nothing else is the same. After searching every corner of the UK for other options, I ended up forking out for the lovely Orangatang 80mm diameter Kegel wheels.

Finally, the ESC. I wanted something familiar and “no fuss” My board is only to use 6s LiPo’s so the Hobbywing 150A Ezrun was my choice.

Haven’t got a pic of it on it’s own so here’s a link for now;

Hobbywing EZRUN MAX8 V3 150A Brushless ESC

ESC came complete with programmer board and the extra capacitor pack so I was made up with it.

I know there are cheaper options out there like the VESC and others but this one was for me.

Right, to be continued, probably tomorrow.

Thanks for the “likes” Cheers for now.

[2-alex-2]

Looking good so far where in uk

[AndyPG]

Thanks Alex, Grimsby, Lincolnshire.

[AndyPG]

Next, a handset to control the speed. Again, I wanted something I could hit the ground running with so I needed a 2.4ghz RC car pistol grip type thing. I could always ebay it if I chose to move to something more compact later.

Flysky FS-GT2B looked good and was only about £20 including receiver and Li-Ion transmitter battery pack.

As soon as it arrived, I bound the transmitter to the receiver and tested it with the ESC and motor. All worked well. The substantial Li-Ion pack came fully charged and judging by the transmitter’s tiny current draw, could last months at a time between charges. Charging is via a USB lead (supplied) Throttle progression is perfectly weighted and pushing the trigger forward applies the brake. Using the ESC programming card, I set the throttle to response to as soft as it would go and the braking to mid point. When performing the braking function, a fairly loud screeching tone is heard. I’d previously read about this, in various posts, but on hearing it for the first time I can see why some might think it a slight annoyance. Ah well, it’ll be a good incentive to leave plenty of stopping distance so as to minimize use of the brake.

I rather fancied a little volt meter which would be visible while I am riding. The obvious place for it, would be recessed into the deck above the front truck. At a little over £5 and about 1" diameter, this is what i chose;

Rated up to 30v, it was just what I needed for my 6s setup.

I’ve been around Li-Po’s for many years so I know the importance of not over discharging them. The ESC is programmable to shut down once the battery reaches a certain voltage. Even so, it’s handy to see what your battery level is so as to avoid a long walk if nothing else. With the 6s system fully charged the volt meter will read 25.2v. I figured that I will use the packs down to say 22.2v and see what mah’s my charger puts back in. With a bit of trial and error, I should quickly learn the optimum voltage which represents the all important 80% discharged point. ie, If my 10000mah pack takes 8000mah’s to fully recharge it, I should be good.

Time for a break so I’ll upload some construction pics later.

Cheers for now.

[AndyPG]

Raining outside now so time for more blog.

The deck looked great once cut into the Loaded Vanguard shape but it wasn’t strong enough. I spanned it between two blocks and tested my 85kg mass on it. It was clear to me that it would definitely break if I put my full weight on it so I had to do something. I’d come this far so determined to use it (if only for a short time) I decided to stiffen it with two poplar wood rails.

These rails would serve as the makings of the battery/ESC compartment so I came to terms with the idea. Obviously all deck flex will be eliminated with the addition of the rails but as I’m not actually a skateboarder, I’d probably not know the difference. I made the rails just deep enough to accommodate the LiPo’s and some foam (top and bottom) to protect them. I glued (PVA) and screwed the rails in place and the deck was then strong enough to support my weight easily. I cut out the hole for the volt meter and then used a router to round the edge of the deck all the way around.

Not exactly cabinet making but I was pretty pleased with it and it hadn’t cost a penny so far. Time for a couple of coats of varnish.

1st Coat

I hung it in my garage on a hook to dry in peace but managed to drop it. Doh…

Ah well, thought things were going well…the balance is restored!

Successful repair…

And a 2nd coat of varnish.

Hmmm… pretty glossy and the wood has darkened a little with the varnish. I rather fancied it paler but too late now. I needn’t have worried. (later)

Cuppa time.

[AndyPG]

Right, trucks!

Wow, what to use? and the choice.

If I could have got my hands on some Caliber trucks at a descent price here in the UK I might have gone for them. Paris V2’s were the second choice but I really wanted some with a squared off type section so that I could use a clamp type method of holding the motor mount on. I’ve got access to aluminium welding equipment but the mechanical approach would allow for lots of adjustment as I went along. You know what it’s like…after studying the job for hours, you say, “yup, lets weld it there” and it turns out later that actually 5mm further to the left would have been better.

So, I wanted some chunky trucks with a hanger width of around 180mm, from a UK supplier for about £40.

Mindless Talisman’s…

I initially wanted them in silver but only black was in stock. They are great looking trucks and after a little bit of machining to further improve the motor mount clamping area, they’re near perfect for the job.

I say “near” perfect as the bushings are quite soft but more on that later.

Next…pulleys.

Again, lots of studying and considering other peoples preferences, I finally decided on the 5mm pitch HTD system. These are the exact ones I chose.

They were only a little over £10 for the pair but do require machining. I have a lathe and a milling machine in my workshop so not a problem, in fact, the machining of the pulleys and motor mount are the bit I’m looking forward to.

With a 5mm pitch I reckoned 9mm belt width was enough and it’s proven to be a good choice. If you go for a 3mm pitch system (like Boosterboard) most recommend a wider belt of say 15mm. If like me you’re using a Turnigy motor, you’ll appreciate the narrower pulleys as the motor shaft is quite short compared to others.

So, another difficult decision, final drive ratio. Again, after lots of studying, I settled on a 15T motor pully and 36T for the wheel to complement my 213kv motor, 80mm wheels and 6s Lipo’s. This gives a ratio of 2.4:1 which has turned out great for my setup. More on that later.

I didn’t order the belt at this stage because I wasn’t sure exactly what length I’d need. My research (reading forum posts) suggested I’d need a 265mm long belt if my motor was 65-70mm from my axle (centre to centre) This turned out to be exactly right So I bought two at around £4 each delivered.

To be continued…

[2-alex-2]

Again looking good I managed to get a pair of calibers used in uk for £20 and were in a good shape. If you haven’t got any yet there’s a few longboard buy and sells on facebook

[AndyPG]

Thanks Alex, I fancied the Calibers long before I realised they are used on the Boostedboard. Might look out for a pair for my next build. Talismans recommended though.

Andy.

[AndyPG]

On to the motor mount.

I machined this from a piece of aluminium flat bar. I aimed for around 65-70mm between the axle and the motor (shaft centre to centre) 10mm clearance between the motor body and the underside of the board. Probably a little over engineered on the thickness but aluminium is light enough and I didn’t want it to give me any bother by way of bending or slipping etc. The thickness where it clamps to the truck might be especially OTT, I suppose, but it is solid. Two M8x60 bolts clamp it in place. Anyway, a picture is worth a thousand words so here’s a few.

Yup, happy with and quite enjoyable to make.

The motor pulley needed boring out to 8mm for the motor shaft and an M4 grub screw threaded hole forming to pinch it on.

Now, I knew some people have had issues with the pulley coming loose so this is what I did.

The motor shaft came precision ground to 8.00mm diameter. I milled a slight flat on it to accept the grub screw. The shaft was very hard and destroyed the little endmill used but it did it. I haven’t got the means to create a keyway so… I bored the motor pulley to 7.97mm and heated it to about 300C. Put the motor in the freezer for an hour and slid the pulley on. Actually I still had to press it on despite the temperature difference and attempt to shrink fit it. Needless to say the pulley is not coming off in a hurry, it is absolutely on there! The grub screw is fitted for belt and braces, and sits on the machined flat with a bit of Loctite on the threads. If I ever want to change the motor pulley it should come off with a custom made little puller or I’ll just zip it off carefully with the miller. It was only £3 after all. As can be seen on the 1st pic, the motor mount is bored sufficiently so the pulley passes through.

The 36T wheel pulley also needed boring out to clear the truck hanger and to reduce its weight! A turned aluminium spacer, between the wheel and the pulley, keeps everything aligned and true. All mating components are shouldered and recessed for a locating fit. I even machined the inner hub of the wheel slightly so that everything mated perfectly and achieved a perfect true running system with zero wobble (run out) and zero oscillation as measured with a dial gauge. The whole assembly is held together with five M6x55 stainless cap head bolts. Definitely should have gone with M5 here as squeezing M6’s in needed a lot of tinkering and drilling. A drilled stainless washer supports the bolts on the outside of the wheel and, again, the outer hub is machined slightly so that the washer sits well. See pics.

Thanks for reading, more tomorrow.

[Byoboard]

Looks good. Looking forward to seeing more.

[AndyPG]

Thanks Byoboard. More to come.

[AndyPG]

So, onward, and time to think about how I might cover the batteries and ESC.

Eventually I hope make a complete carbon laminate enclosure or maybe try vac forming a plastic one but until then I need some sheet material to simply clad the poplar rails. 2mm thick aluminium sheet is to hand so that should be fine for now. Simply bent it to shape in a vice between a couple of pieces of angle iron improvised jaw extensions. A few screws around the perimeter and I should be up and running.

As you can see, the 150A ESC is quite a chunky thing and protrudes inconveniently above the aluminium sheet.

No problem, the built in fan needs a fresh air supply anyway so I make a cutout for it and begin thinking about how I might protect it from bashes and splashes etc.

I’m gathering pace now as I’m tantalizingly close to a test run. Got to be careful though as it’s easy to end up with a part that’s taken hours to make but not fit for purpose.

A night’s sleep and the idea came. An hour of tinkering and its fitted with four pop rivets.

Happy with that. Keeps the splashes out and offers some impact protection. The air drawn in by the fan will exit from a slot where the motor phase wires come out.

The little hole is so I can operate the ESC push button on/off switch with a pokey thing. To be improved at a later date.

I also modified the entire aluminium cover so that it was in three pieces. This allows just the centre section to be removed for access to the LiPo balance plugs. The two lap type joints also stiffen the ally sheet consiterably.

It’s not as posh as the carbon enclosure I dream of, but this is prototype one, it looks low profile and I’m pleased with the result.

More soon…

[AndyPG]

What next?..

Wiring I guess.

I’m using four 5000mah 3s Zippy packs because I have quite a few of them. These are my staple pack for long range FPV model aircraft flying.

I may well look at Li-Ion at a later date but considering I already have the LiPo’s, it’s a no brainer.

The ESC has a push button on/off switch for activating and shutting down the ESC. Obviously the ESC must have a small stand-by current draw for the switch to work so I knew I would want to be able to completely disconnect the power from the Lipo’s between rides.

To do this I had the great idea of using an XT90 connector, with a bridging link wire, as a heavy duty isolator. Of course, I later find that it’s a well established method so no break through there.

I have an external charging port (XT60 connector) but the LiPo balance leads will have to be accessed through the central ally cover panel for now.

Anyway, here’s a thousand words in the form of a picture to show how my wiring looks.

The fuse is an 80A lorry (truck) fuse.

I reckon I could go lower, maybe down to 60A, and I’ll experiment at a later date. I included the fuse mainly to protect the rather pricey ESC. 80A is fine for now as the ESC is supposedly rated at 150A continuous and a whopping 950A burst! Even if these manufacturer’s figures are a bit optimistic, I’ve made an effort with protection.

On to another job I’d been looking forward to…Grip Tape.

This was £2 delivered for a 36" x 9" piece. And a free sticker too.

I took a liking to the sticker so decided to incorporate it into my chosen grip tape design.

I wasn’t over pleased with the overall look in the end, mainly because the deck turned out too dark after varnishing, but it did grow on me during it’s short life.

Also a slight oversight, was the gaps in the grip tape design manage to inconveniently show my poplar rail fixing screws. Slightly spoilt the effect and something to watch out for next time.

As most will know, the grip tape design is based on one of Loaded’s patterns.

Next, how did it ride…

[AndyPG]

Wow, what a moment, that first ride. I’m 50 and haven’t got a skateboarding background so it was pretty exciting. I have, however, spent 30+ years water skiing and wakeboarding and I have, of course, been on a skateboard from time to time.

So…it was a lot faster than I thought and went a lot further than I thought.

I’d calculated a maximum theoretical speed of 32kmh based on motor kv, battery voltage, drive ratio and wheel diameter. I’d no idea what part friction and air resistance would play and was surprised to learn…not a lot. On a good surface I have recorded 30.8kmh and 30.5kmh several times! On a fresh charge is seems even faster but I’ve only done speed tests after about 20mins of use. It’s a little scary for me so I feel much safer at around 15-20kmh and even dabble in some carving.

It charges up modest hills with barely any noticeable drop in speed, just a change in motor tone. I haven’t measured the angle it will climb.

Acceleration is plenty. I have the ramp up time as soft as it will go and I still have to lean well forward.

Range varies with terrain. In an open environment like extended road or cycle track, 20km is about it. In town with lots of stopping and starting, ramps and drop kerbs etc, I’m down to 12-14km. I would say if you tickled it on a long flat, un-interrupted route, 25+km might be possible.

So, after a gentle but varied 20km run I’ve used 8000mah of the 10000mah battery capacity. I average 16kmh so a 20km run takes me an hour and a quarter. This means I’m averaging 6.4A, over said run, which is a lot lower than I thought was possible.

More analysis soon and details of my mishap.

[AndyPG]

I’ve had quite a few sessions now and getting to know the board quite well.

So, from the ground up…my thoughts…

The 80mm Oragatang wheels are great. They do a great job of tackling dodgy pavements and steps of up to 1/2" or so. The durometer spec is perfect for grip, wear rate and ride comfort. Big is best, for hacking around on rough streets, so some 90+mm FlyWheels would be better still IMO.

The Mindless Talisman trucks look absolutely stunning. They have a lovely feel but I suspect they are slightly softer than an ideal esk8 choice. I adjusted the bush compression considerably and this much reduced the sensitivity and thus the tendency to wobble at speed. However, the lipped washers started chaffing on the hanger so I had to relieve the lip a little to allow that little bit of extra adjustment needed to get them just right.

The 3s 5000mah Zippy LiPo’s are great batteries. They seem to serve me well with my other interests so seeing as I had them already, happy with! I do, however, look after all my Lipo’s with a fanatical approach. I never store them fully charged and I never over discharge them. Anyway, there’s plenty written on LiPo care so…moving on.

The EzRun ESC. Works perfectly and never gets beyond warm. I reckon it’d probably be OK without the fan, which would reduce it’s profile considerably, but maybe another time and with caution! The only negative point with the ESC is the well documented screeching noise it makes under braking. Certainly makes you think about slowing down early so that you don’t have to use it, especially if there’s people around.

The voltmeter…perfect in every way. Lets me monitor exactly what state of discharge the LiPo’s are at, as I ride. Essential in my book.

The home made deck? Mmmm, not nearly strong enough, made with the materials I used. The Vanguard shape is also a little uncomfortable for me. I now believe commercial decks are good value so probably wouldn’t make another. Even the £20 ebay ones are better than I can produce so I’ll leave DIY deck building to the more talented among us.

The 2.4ghz controller? For £20 you really can’t go wrong. It would benefit from a good hack and rebuild to make it smaller. Something for the future.

So, I’m riding along and I hit a ramp in the road where the tarmac is out of level. A loud crack noise comes from the rear end of the deck but all seems ok. When I say ok, if I’m honest, it does seem a tiny bit more bendy at the rear. I decide to order a cheap maple deck off Ebay to use for prototype 2 as this deck’s days are now numbered. Two trips later, and out of no-where, my deck suddenly snaps on me while cruising on perfect smooth pavement! I step off easily and quickly but I’m pretty gutted as the beautiful SK3 motor has briefly served as a wheel and in the blink of an eye, it now looks 20 years old. Here’s 4000 words worth of pictures as writing about it is painful.

Ah well, that’s christened it as they say.

I’m now up and running again with by new Ebay deck. It’s a great deck really and very comfortable.

So that brings the tale up to date.

As soon as we get a descent day I’ll take some more pics and do a little video of it in action. I have a few minor improvements in mind which I’ll bring to the forum but for now I’m gonna get some miles on it.

Cheers for now. Hopefully a video in a few days.

[2-alex-2]

Really bad luck with the decks but looking at it maybe cause by the self taping screws. I drill and insert t-nuts as its a clean hole where as a screw can pull the lawyers apart and also if no pilot hole will crack it as it goes in and weakening it.

[AndyPG]

Thanks mate, Sounds good, I’ll look at those.

[2-alex-2]

Did the first board go in the same place.

[AndyPG]

Only the first board failed. The second (Maple laminate) board is fine at present. Andy.