First some purrty pics:
Parts List:
Trucks: @Titoxd1000 dualities
Motors: Hobbywing 56118 650kv’s from @hoytkid
Drivetrain: Tito inrunner short mounts, custom 17:120 mod1 open gears (more on that later)
Wheels/Tires: @tomiboi hubba hubs, Mboards supernova tires
Deck: @tomiboi hellhound, custom removeable spine for track
Battery: 12s10p P42a
ESC: MakerX 2G300
Enclosures: @3DServisas esc box, printed battery box
Extra tech: pre-production Radium RTS module, Davega telemetry screen
Here’s a play by play of how this board came to be:
This board’s life started over a year ago with the completion of its predecessor MyBlueBoard, it had an 18s5p with p42a’s built by yours truly, Reacher 173kv 6485 motors, the same hellhound deck (albeit a fair bit flexier than it is now), 300mm dualities, @IDEA short open gear mounts, Tomiboi hubba hubs, XCell RS tires, a d100s, and @MoeStooge 67t spurs
The Good: This board rode great, the gears held up fantastic for well over a thousand miles, and in that time I only went through one set of tires, the board also had a really comfortable ride because of how flexy the deck was, it was stable as hell, could go as fast as I wanted it to, it also had this great feel in the corners, it was like the board was hugging me when I’d turn, it really felt like when it was dialed the board disappeared under my feet, it even carried me to the pro finals at my first esk8con, got me second place on the podium at Tef1 Atlantic, and third place at Heartland PEV fest
The Bad: At the time when I had built it I thought it had oodles of torque, pushing 135a per side out of the d100s had me plenty happy, untillll I raced people like @MacKeeper28 who were willing to push their d100s’s far harder than my paranoid ass, simply put I needed more launch. What I also needed more of was top speed, the board was no slouch for the street but the 40 something mph top speed felt like it could cost me if I found myself on a longer track where you have madlads like @HAIRYMANJACK pushing 60+mph. Another issue was grip, the RS tires were good for street but it was apparent when I was going up against people on Linn slicks, BRP’s, and Supernovas that if I wanted to be more competitive I’d need to get some more grip. The last issue was the deck flex, while for street it was super fun and really comfy it left a bit to be desired on the track, as I got faster and learned to shift my weight around better in corners I realized the board has a really noticeable amount of torsional flex, if I shifted the weight on my back foot the wrong way the tail could twist independent of the nose and induce super violent speed wobbles.
**So…I now had a blueprint for what I wanted in a race board, more stiff, more speed, more grip, more torque
First, the stiff:** Now my intention was still to street ride this board, flying two boards to vegas would add too much extra cost so whatever board I’m racing needs to also be usable for the group rides. After street riding a stiff deck and a flexy fun deck I’ll take flexy any day of the week, but as we’ve established flexy no good for racing, if only I could have the board be stiff like a stooge on track but flexy and fun like MyBlueBoard on the street, sooooo here’s what that resulted in: an extra carbon layer I laminated onto the underside of the deck to cut down on some of the sag and kill the torsional flex, and a removeable spine made with half inch steel square stock.
With @MacKeeper28 ‘s help planning it and a local rider Beni’s help welding it we ended up with this prototype. There’s still a little little bit of flex so I may move up to 3/4” stock but it’s a hell of a lot stiffer and more linear feeling than it was before, and there is just about zero torsional flex
Next Up: More Torque and Top Speed
Now clearly all the cool kids are running inrunners, and that means running some beefy controllers too, lucky for me MakerX just released the 2G300 which ticks pretty much all the boxes, dummy headroom for voltage, dummy headroom for amps, and not as heavy on the wallet as getting two g300’s individually. @hoytkid also gave me a good price on some lightly used 56118 motors so I jumped on those too. Now, a beefy controller and big ol motors are good but they’re nothing without a beefy drivetrain to transmit all that power, initially I wanted to go with stooge spurs since they had worked well for me in the past but the 11:78 ratio I see being used by others has one fatal flaw: excessive tooth wear. Now this isn’t the fault of the gear quality, this is just the nature of gear drives. Something you need to take into account when finding a ratio to use is how “random” the ratio is, if it’s too regular then you end up with a problem where the same teeth on the motor pinion are hitting the same teeth on the wheel gear repeatedly, accelerating wear and leading to the shredded pinions I see so often from those running the 78t spurs, you can check this yourselves by simply dividing the tooth count of your wheel spur by the tooth count of your motor pinion, in the case of the stooge setup you would divide 78 by 11, resulting in 7.0909 repeating, now this repeating part is exactly the regularity I’m trying to avoid. The solution I had to this was to first swap to mod1 teeth, smaller tooth modulus means more teeth on the gear and gives me a better chance of finding a motor pinion tooth count that gets me close to the same ratio as the 11:78 stooge combo without the excessive wear. That led me to the final ratio of 17t motor to 120t wheel, which if I use the same math for results in a ratio of 7.05882352941, that random number is exactly what I wanted.
After seeing @jack.luis ‘s success in making his own gears with the help of cheap chinese manufacturing I decided to embark on a similar endeavor. I mocked up my gears in CAD with some basic cutouts for weight reduction and MBS mounting holes, waited a few weeks and V1 arrived in the mail. They bolted up to my hubba hubs perfectly, and the center bores were perfectly sized to accept center fit bearings, an absolute success!
Now that v1 was in hand I was immediately looking to work on V2, more weight reduction, and more compatibility with wheel hubs, so I swapped to circular cutouts to trim on weight and cost, and extended the MBS mounting holes into slots that cover everything from MBS profile to stooge pattern. Fingers crossed I should have the new gears in hand in the next few weeks but for the time being v1 will work to get the board rolling.
Finishing the Drivetrain:
Now that I had gears I also needed mounts, for which @Titoxd1000 came in absolutely clutch as turns out he had been working on mounts specifically made for the mounting pattern of hobbywing inrunner motors, coupled with some 270mm wide dualities and the fitment is just immaculate, sorry stooge fellas I think the straight bar of motors just looks better
**The Spicy Pillow: **
For this build I decided to go with a 12s10p with molicel p42a’s, initially I wanted to go with a 14s or 16s pack using eve50pl’s however after the whole snafoo with CCC vs non CCC and endless QC issues I decided to just stick with the tried and true, plus I had tons of them sitting around.
Build was straight forward, my new AwithZ P30c graciously provided by @stan_he made quick work of all the welding, and surprisingly enough my pinecil was good enough to solder a massive length of 8awg wire across the full length of both main positive and main negative, I figured I wanted to beef up the ampacity of those connections as much as I could since these motors are stupid amp hungry and my intention is to push these p42a’s to the absolute limit. Assuming all goes well this pack should be able to burst up to 22.68kw, though who knows how close I’ll actually get to that
With the pillow done I also needed somewhere to house it, so I came up with this: a 3d printed set of walls that perfectly mirror the contour of the top of my deck with a passthrough qs8 and 8awg cable for discharge, that way I can have this big ol battery be about as compact as possible. There’s just enough room on every side for a bit of foam to keep everything nice and safe plus plenty of cushion on the top and bottom of the pack. Got to dry fit everything together and I finally had a look at how the final board was gonna look
RTS Install Babyyyyyy:
So I actually have been sitting with a prototype RTS module in my possession for the better part of a year now, bought it on impulse when I had a chance and always intended to install it on a build but with how timelines got shifted around I didn’t end up getting to it until now
Now outside of radium test boards afaik we have yet to have seen the RTS system be adapted onto a diy platform, aaannndddd I can see why because getting this kit to fit on the dualities was a process. Step one was figuring out the wiring, which was actually the easiest part, just cut a channel in the top of the deck and route the cable through, ezpz.
Nowwww the hard stuff, actually mounting the steering sensor. Now on the mach one this was intended for the hanger/baseplate already have the necessary mounting points and hardware, that isn’t the case with the dualities (duh). After figuring out exactly how I’d need to orient the sensor I got to work, with some carbide bits and an all too shaky hand I started grinding away at a pivot cup for my 450 dollar skateboard trucks. After drilling and tapping some m3 holes I had done it, the sensor module was mounted successfully! Next step was to figure out how to mount the magnets in the hanger so the sensor actually had something to…sense.
Plus side to doing this on dualities is that both the front and rear trucks have printed lean stoppers that screw to the hanger, so I figured I could avoid needing to make permanent modifications to the hanger by printing custom lean stoppers with magnets embedded in them. After 9 different iterations with various magnet spacing, sizes, and distances from the sensor I finally nailed it! the sensor was outputting the correct data and was reading the full range of lean on the dualities! Alright, that’s the hard part done, now just some wiring goodness and I was off to the races (literally!).
**Finishing Her Up and Getting in a Test Ride: **
I rammed the battery into the box with some foam, ran the cabling for the discharge and davega, covered all that goodness in a layer of tesa tape then grip tape, and finally ran all my cabling to those glorious g300’s. Soldered some lug connectors onto the motors and all that was left was figuring out fitting all the electronics in the esc box, which after some trial and error looked like it would be able to fit everything I needed if I just printed a little spacer for the lid to sit a bit taller
Got the spacer printed and cut some cable channels and the build is ready to roll, and I used just about every single jst available on the controller!
Final Thoughts:
After the first ride I am sooo soooo happy with how this build turned out, RTS on a mach one already feels great but feeling it with these ultra powerful motors and super grippy tires just makes it feel even better, feels like the board is actively cinching down the bushings on hard acceleration and keeping me locked in then loosening the bushings for sharp turns, it’s everything I could’ve wanted, super excited to get some more time/mileage with it so I can better tune it for my liking.
The top speed is just so much, and the torque is just what I wanted, pushing 350a per side, so far I’ve only managed to reach maybe 3/4 throttle on launches and it still feels like the board is putting my stomach in my shoes.
Surprisingly the efficiency doesn’t seem too bad so far, got about 47wh/mile over the course of 7 miles so that should net me at least 30 miles on a charge, not amazing for an 1800+wh pack but considering other people are reporting 100+wh/mile efficiency on these same motors I won’t complain, it’ll at least get me through the group rides which is all I need it to do.
The removeable spine is a semi success, coupled with the stiffness from the battery box and the carbon on the deck the deck is almost totally rigid when its attached and still retrains the flexy fun dampening effects from this board’s predecessor, butttt it’s still not 100 percent stiff, so I may look into adding more steel to it in the future.
The custom gears are holding up well so far, I’ve also got some custom 17t motor pinions coming that are specifically made to fit the hobbywing d-shaft profile so I’ll update this thread with how testing on that goes, right now I’ve got some cheapo amazon pinions on the board which work but are showing a fair bit of wear despite how few miles the board has had so far.
