esk8.news esk8 calc donate now

Biribiri | MBS Comp 95 | Spintend | FS6374 | Chain Drive

I took advantage of this holiday season to build my first board, and incredibly the time from first parts procurement to a finished board was just under 3 months.

This post is a summary of the entire build process because Discourse sucks for drafting, I have a far more detailed but boring build log that I maintained during the build process in a blog. If you’re interested in that, feel free to check it out here.

Pictures

Requirements

Budget was definitely the biggest requirement, but at the same time I didn't like the look of some of the parts of the Skatemetric Patriot build, and wanted to get a slight upgrade from those. I wanted a mountainboard instead of a carver, because a mountainboard can also carve reasonably well, but a carver can't go offroad well. I wanted the enclosures to be completely waterproof, so I needed to minimize the number of holes drilled, and waterproof those that are. I wanted all the parts to be modular, so everything could be easily swapped or replaced without the need of a soldering iron. I got a lot of inspiration from some of the builds on this forum, so that was a major influence on parts picking and design.

Parts

All parts are brand new. Used might have been a better idea, but most of these had free shipping which didn't make it that bad.

Base: MBS Comp 95 “Birds” Complete

ESC: Spintend uBox with Uni1 Remote

Motors: 2x Flipsky 6374 190kv Battle-hardened

Batteries: 2x Tattu 6S 14Ah LiPos (Thanks @AK1!)

Mounts: Boardnamics Matrix II Mounts

Battery Enclosure: Apache 1800

ESC Enclosure: Zulkit Junction Box

Drive: Homemade #25 chain drive, 10T/62T

All in all, total cost for this build including taxes and shipping was just under $1200. That brings it in direct competition with many prebuilt AT boards like the Wowgo AT2, and even under some such as the Backfire Ranger X3 and Evolve.

Build

The build kicked off with the purchase of the uBox, as the price was going to go up, and I decided to go with it for futureproofing. It seemed like a solid product, and so far it's maintained that reputation. Then goes another two weeks-ish, when 11.11 started. That kicked off some more purchases, including the Flipsky motors, which were only $65 each! Then another lull until Black Friday and the week after, when I got the MBS complete, motor mounts, batteries, chain parts, and enclosures. The other odds and ends came from Amazon, so they were ordered here and there as I needed them.

Thanks to logistical delays, the board itself didn’t ship and deliver until Christmas Eve, and the batteries were stuck in a USPS distribution center for well over a month. I couldn’t do any building without the actual board, and I couldn’t test the electronics either without a battery, so the build really started around Christmas.

After getting the board, the first thing I did was start on the chain drive. I had designed and 3D printed a jig to match the bolt pattern of an MBS hub, but I wanted an actual hub to compare it against just in case it was off slightly. It looked fine though, so I drilled out the hole pattern on the wheel sprocket. However, it turned out that the center hole was ever so slightly too small, so I had to ream that out with a step drill bit, which was a bit of a pain. Once that was done however, I attached the sprocket onto the hub with 65mm bolts, with 2 10mm spacers in between.

Then came the motor mounts, which were fairly straightforward to install. It was kind of confusing to figure out the correct orientation however, as most sides were generally right, but one face was much flatter than the actual hangar profile. As such, when tightened, only 3 or 4 sides of the clamp actually contact the hangar instead of full contact. Seems pretty strong though, and I was worried that if I tried to round it the mount pattern wouldn’t align, so I didn’t try fixing that face. There is a tiny bit of bite from the clamps when I lean all the way, and I haven’t really figured out a good solution for that yet aside from chopping the corners off the deck. I’ll need to think about it more.

The enclosures were tricky to position, but once that got locked down, it was pretty easy to make. Because I didn’t want to shorten any of the ESC or motor wires, and I didn’t want any connections outside of the enclosure, I elected to place the ESC backwards in the enclosure, and use the length to take up wire slack. The ESC is also slightly off center to make room for the power switch, and so the power could reach the exit way off on the side. I also fiddled with the battery box orientation, before settling on the long side matching the board because the sides of the box were flat, while the front and back had ribs, which would make exiting a connector difficult. The XT90 holes were cut with a dremel, and I glued on 3D printed panel mounts using waterproof silicone adhesive. The motor umbilicals came through holes in the back of the ESC enclosure cut with the step bit, and are sealed using cable glands. As a side note, I accidentally drilled them slightly too close here, so you can’t tighten both at the same time. I call it an antivibration feature, although in the future they should be at least 2mm further apart. The enclosures and board then got some industrial outdoor Velcro to keep them together, and it’s surprisingly strong.

Final things included soldering a bridge cable between the battery and ESC enclosures, and cutting the chain for the drives. The soldering went shockingly well, as I did not anticipate my cheap 25W (or 40W, models look identical so not sure) Weller with a conical tip getting close enough to heat through 10 AWG. Yet it managed to fully tin the ends, and the connectors as well. Unfortunately I went too hard with the solder, and accidentally overflowed out the connector a little so the little end cap doesn’t go back on. I ended up snipping as much of it off, and then taping over the gap. As for the chain, it took me 3 hours and two ruined punches to get three of the pins out without a chain tool just so I can get 2 lengths of 18". Get a chain tool, you’ll thank me later.

VESC programming was a little challenging, as you’ve probably seen a few of my questions on the noob thread. I had (and still have) no idea what I’m doing, and it took a few tries and reflashes before it was set up properly. I have it currently set to 65/-65 for motor, and 80/-20 for battery, so we’ll see how that goes. I’ll tune it as I keep on riding and experimenting.

First Ride

The first ride was an interesting one. Having come from a Wowgo 2s, there were a lot of firsts. First mountainboard, first time with bindings, first time on pneumatics, first time with outrunners, you name it. I found it quite aggressive in throttle response and braking, compared to the smoothness in Hobbywing ESCs and hub motors. Even letting off the throttle had a massive jolt, whereas I did it all the time on the Wowgo to coast. Bindings are kinda nice, but also a little restrictive. I couldn't get the rear binding feeling right during my test session, so my foot kept slipping out when I did a jump rotation. The Velcro meanwhile holds well, and withstands small hops and jumps no problem. Channel trucks feel like top mounts, although the width needs a lot more leverage to turn at slow speeds. I tightened the rear bushings to minimize motor mount bite, but that actually made off roading more difficult, as the outboard wheel kept on lifting during a turn and losing grip. Pneumatics are an interesting feel, and even more so is the raw power compared to the early 250W hubs on the Wowgo. It's going to take a few rides to get used to it.

Conclusion

Is it a pretty board? Eh not really. But it's much more capable than a prebuilt at the same price, while leaving lots of headroom for upgradeability in the future. Plus, if I feel bored, I can convert it back to a gravity board in five minutes by pulling off the enclosures and removing the motor mounts. There's already lots of upgrades and modifications I have planned. It's going to be quite interesting updating this thread in the future!
18 Likes

Reserved for idk what yet

3 Likes

Great achievement on a budget!!

Did you notice any slippage on the velcro at all? Id love to use velcro to hold a peli down but seems risky :woozy_face:

3 Likes

Nope, their industrial stuff is pretty sturdy. The hooks are different from normal Velcro, with two barbs and a thicker stem. I’ll have to see how they hold up long term, but I’m not removing it often so I think it should last a while. It’s supposed to be good for 1lb per square inch, and I used 15 sq in for the battery enclosure, which should be ok since gravity keeps it in place as well.

2 Likes

Velcro losses its velcro-ish-ness when exposed to the environment. I heard reports of battery boxes falling off with 3M dual lock which is supposed to be the strongest of velcros. Vibrations are the killer here.
Make sure to have some sort of extra anchor point!

Also super nice build, great example of price/quality ratio I’ve seen yet for a MTB!

3 Likes

Hmm yeah I’ll keep that in mind. There’s lock holes on the box, so I can tether it to the binding through those just in case.

Definitely a lot of things to get used to but a great build to price ratio.

For the throttle jolt, try messing with the negative throttle ramping speed (or something very similar near throttle curve mapping)

2 Likes

I was thinking about building something similar with the MBS Comp 95 Mountainboard complete. how did you get the 20% off coupon?

It was an old code that expired in December. Even still, the regular permanent 15% off code for this forum (ESK8BUILD15) is pretty close.

1 Like

image

9 Likes

This is a fine example of quality to price ratio wholesomeness. Good job!

5 Likes

I do it. It’s fine. Never budged, even after hard falls where the board rolled head over heel on asphalt.

1 Like

Honestly I attribute that to how far this hobby’s come along in a short while. The fact we can get $250 VESC75/300 ESCs and decent sub $100 motors would have been unthinkable even one or two years ago. Even in the prebuilt space, the boards have come a long way.

5 Likes

would you mind linking the chain drive components?

Sure thing, although looks like the exact wheel sprocket is OOS. You can also most likely find everything cheaper elsewhere, but hey free Prime 2 day shipping.

Wheel Sprocket: https://www.amazon.com/gp/product/B06WGQFY77/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
Motor Sprocket: https://www.amazon.com/gp/product/B07RB2R767/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
Chain: https://www.amazon.com/gp/product/B07NPNFDRP/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

If I were to build again I would have gone straight for the 12 tooth motor sprocket instead. 10 is great for off road, but a little slow on the road and noisy. 12 should be a much better hybrid gearing.

3 Likes

Learned a bit about the limitations of Velcro today. I used a little bit to mount a tail light to the rear enclosure so I could easily remove it when going offroad or to charge it, and while it holds up fine during regular riding, it fell off during a jump. Looking more closely, it appears that in this particular Velcro, the hooks are directional, and are facing sideways rather than vertically. Had it been rotated, it might have held better. Also, the surface area is pretty low and it’s mounted at an angle, which doesn’t help. I believe 3M dual lock should hold better in this application, where there is no expected flex in either component.

Also printed a GoPro mount for the front of the deck just because. Footage angle isn’t terrible, although I think I need to shim it with some tape to reduce vibrations, as with a dive housing it just sounds like bass boosted wind noise at any speed. It almost drowns out the drivetrain noise, which is pretty impressive considering this is a chain drive. I tested with a generic action cam for the maiden ride, gonna swap to my actual GoPro to see if it improves.

3 Likes

Finally got my complete today. Thanks for telling me the coupon!

I am wondering if you have had any issues with the plastic trucks on this board. I just watched a video where a guy snapped them. https://www.youtube.com/watch?v=gzbokRtZcEk

Haven’t had any problems yet, but I’m fully expecting it to fail eventually. At that point I’ll switch to the metal baseplate, and order other stuff off MBS to reach the free shipping threshold.

how long have you had them for?

A little over a month. Not as much riding as I’d like due to the weather, but got a lot of practice hopping around on the board in the yard. Totally see why heelstraps are nice, and looking forward to get some in the future.