The belted one wheel experiment

[Fosterqc]

In my dream world a 6384 motor is fine. So be it if you want to go faster than 10mph that you need two 6374 motors. Probably not gonna work out tbh.

Wow that is a big fat motor you linked. Im sure sure how durable they make those things. Lotta weight spinning around.
I thought you meant like this size

KDE6213XF-185 Brushless Motor for Heavy-Lift Electric Multi-Rotor (UAS) Series

My serious answer to what motor I would use after I tested with a 6384 is probably something oversized I guess larger than 80100.

This is the kind of dumb idea I usually save for my own threads but you could take two floatwheel hubs and put them where the batteries normally are, chain drives to hub in middle. Problem solved.

That dual motor board (almost 3 wheel like) would actually be more suited for a tank track drive system. Again definitely something silly.

[lock]

Discovered the other day that I have roll to start enabled. Not sure how I feel about this, kind of dangerous, kind of neat. I just need to learn how to balance on it while off for the 10 seconds or so it takes to boot up

The 12t motor pulley arrived (down from 22t), this gives a new max speed of 34km/h (21mph). Whatever tune parameters I was using on the old gearing were just garbage so I scraped them all and went back to a default set of parameters I grabbed from pev.dev. Unlike last time, these worked really quite well. It rides differently to the Pint, not worse, just different. More tweaking required.

The whole rear end of the board needs to be disassembled to change out the motor pulley. That’s a lot of screws.

The smaller pulley saves about 250g (0.6lbs), which is great, the board now weighs 12.9kg (28.4lbs). The downside is it just kind of sits angled nose down yet not touching the ground, not very “OneWheel”

Low speed performance on longish grass still isn’t great. I see the highest battery/motor current in this situation along with some cogging (not as bad as with old gearing). I’ve got some AS5047 encoders on order to see if this helps with the low speed stuff. Not sure how I feel about the slower top speed, I’ll hardly be pushing that any time soon, but may still investigate field weakening. I’ve also got a 15t pulley to try out.

I’m a little concerned about losing a bunch of teeth on the motor pulley, and this leading to belt slippage. Considering introducing an idler pulley that would run the belt like shown below. Definitely better tooth engagement, but to implement it I’d probably screw a 10mm shoulder bolt (m8 thread) into the rail. It’d be cantilevered and may introduce a bit of flex into the system.

Smaller pulley worked out better than I expected, and before testing I was seriously looking around at other motor options. Some good options from Neumotor, but I think I like this one from Revolt more (bigger, cheaper). Trying to fit it under the board could be problematic. Image below shows the 80mm layout vs the 107mm diameter of this motor.

Of course really what it needs right now is for me to get padded up and take it out for a decent ride.

[lock]

Encoder finally showed up . Those cheap AS5047p encoders from AliExpress don’t come with the special magnets. Fortunately, there’s one online store in all of Australia that seemed to stock diametrically magnetized magnets, so I didn’t need to wait another month to ship some from China. I’m not against Digi-Key etc, it’s just the shipping was going to cost more than the part!

Followed this awesome FreeSK8 guide for wiring up the encoder, and it all worked out great. Was worried about using 5v as it supposedly results in more noise, but I see at most 0.1 degrees of noise in the signal, and that seems good to me.

All wired up in its 3D printed housing.

And then installed on the board. Testing out an encoder was always part of the plan, so this space was kind of reserved for it. Housing bolts up to the standard 44mm bolt pattern 63mm motors use.

I used one of surfdado’s tests to see if the encoder helps at all. I’m sure there are better tests, but all you need is a few planks of wood so . Much less subjective than taking it for a ride to see if it “feels better”.

Anyway here’s a bunch of before and after footage wrapped up in a nice short YouTube clip.

Belt driven VESC OneWheel - torque testing with encoder

tl;dr - It helped a LOT!

Neither the Pint or this board (pre-encoder) were able to clear the 25mm step. That said, the Pint did have much better low-speed torque which had me thinking. My current theory is that the OneWheel hubs have 30 magnets whereas I have 14, this means the hall sensors will be switched twice as often allowing the OneWheel much better motor tracking.

[Fosterqc]

@lock

IMG_5349960×1280 152 KB

All that oomph on 12S! wicked!!!

[lock]

Got padded out and took it out for a ride today. Did not get dropped on my face, so overall I’ll call it a win.

Belt driven OneWheel - test ride

Rode for a total of 6km (3.7mi), a mix of mostly concrete paths but with a bit of dirt/grass. Tried to really push it on a few of the little hills around, well push it as much as I was comfortable with. Below includes the data from the short ride in the above clip. That grass section is a reasonably steep little hill.

Nothing really seemed off, well that’s until I stopped to feel the motor (there’s no temp sensor), it was hot enough not to be able to touch for long . Stopped to let it cool before doing more hill repeats. It was a hot day today (35°C / 95°F), but I expect this could still be an issue on cooler days. Rails were quite warm too which is good/bad; good that the heat is being transferred to them (they’re effectively a 2.5kg heatsink), bad that it still didn’t keep temps in check.

I suspect that despite all the documented ratings, the 80100 motor in 50kv form, really isn’t good for the kind of amps I’m feeding it.

Pushed it on the way home up to the duty cycle tiltback (80%) while watching the VESC RT data just to check if the board would actually tilt back. It did. This worked out to be a little over 26km/h (16mph), which is faster than I’ve gone on my Pint. Consumption wise it averaged 15wh/km, not sure how that compares. Probably had less than 10psi in the tire.

[Flyboy]

You can try this fan, but idk if you rev high enough to get good use out of it

3D printables for esk8

Here’s a cooling fan to bolt on top of APS 80100 motors and any other rebrand that uses this can: [image] it mounts with M5 socket screws, 10-20mm long. In my testing it cut my motor temp from 45C-50C to 35C, in ambient conditions of 20C. [image] 80100 impeller.stl (6.6 MB)

[lock]

That’s a nice fan! But as you said, I don’t think the motor is going to be spinning fast enough for it to generate enough airflow to make a difference. Was thinking about something like a powered CPU cooling fan, but I’m not sure that would make much of a difference either.

Kind of feels like treating the symptom and not the cause.

[Flyboy]

I feel ya. I don’t have great thermals on my 80100 motor either, this model line was really made for airplanes to give them ram air cooling

[lock]

Glamour shot for 2022 BotY - thanks @BenjaminF . I’ll opt to put this in the innovation category. It’s not an esk8, so probably fits best, and I probably do 50/50 when it comes to street vs offroad anyway.

It’s a bit dirtier/banged up now, and I like it, looked way too clean in some of those other ‘just finished’ photos.

Thanks for the nomination BTW @Flyboy

[Piercedsoul]

I know you’re still fine tuning it, but how does it feel now compared to the pint?

[lock]

The best answer I can really give is “different”, but that’s a cop-out. I honestly don’t have enough OneWheel experience; in ride time or board variety, to be a great judge here. I’d like to get others’ feedback at some stage but need to be confident in the board first. The local (Melbourne, Aus) OneWheel group seems fairly active, although I’m not sure how down the VESC rabbit hole any of them have gone.

I really need to figure out some good back-to-back performance tests; something less subjective than ‘feels good’. If it’s beating the Pint it’s at least in the same ballpark as other OneWheels. I’d love something like a OneWheel dyno.

I ride the Pint with 18psi in the tire, always thought that’s just the way OneWheels ride. This thing I keep at about 12psi or so, I’m pretty sure the tire has a slow leak and settles around this pressure. Its tire is 0.5 in bigger in outside diameter, and 1in smaller on the inside diameter (5in hub); that adds up to a fair bit more sidewall. There’s none of that getting bounced side-to-side like on the Pint, and a lot of the bumps (say up to an inch) you really notice on the Pint just seem to not be there. But then maybe an XR with low pressure and its wider tire would be the same

It’s quicker than the Pint; both in top speed (not by much) and acceleration. I’ve not tried field weakening yet so that could potentially bump up the top speed. Not hitting any battery limits (30a is about the max I’ve seen from a 12s3p p42a), and the VESC doesn’t seem to be overheating. I did some stationary hill starts on a concrete path and really stomped on the front, this it handled well. Repeating the same on a similarly sloped grass hill gives moments where it feels like you need to be careful/backoff. The Pint kind of always feels like that on grass.

Interestingly there’s no feel of belt slop. Rocking back and forth in the spot feels very much like the Pint. Hasn’t skipped a tooth yet either. Not that it would skip a single tooth; it’s more likely any skip would kick the PID loop into overdrive and shred the belt entirely.

[Piercedsoul]

I don’t know if you’re aware of the float wheel (mass produced VESC board currently being developed/manufactured) , but they recently teased the idea of a belt driven version.

There’s a Reddit thread here about it, with a few opinions on the topic, some will be more helpful than others. Something I didn’t know is that the original onewheels were belt driven

[lock]

The floatwheel guy has actually been commenting on my YouTube video, interested to see if he goes anywhere with the belt idea. I’d say it sounds like he has a bit of spare time right now with the New Year going on, but otherwise, you’d think he’d be really quite busy. Seems to be making impressive progress!

Interesting. I do wonder what an encoder would do for hub drives.

There’s been some fun takes on various social media sites. This one is still my favorite.

I do get the concern about the belt slipping; it’s obviously a much bigger issue here than on an esk8. I don’t think people quite get how stiff/strong these belts are. It’s the same belt spec used by quarter midget race cars (dirt karts), htd8m belts are often used to power car superchargers (albeit at a 75mm width). It should be possible to engineer a system that will never slip for thousands of kms.

[ShutterShock]

@lock

think people quite get how stiff/strong these belts are

I think most people are stuck on htd5m which definitely skips at extreme torque, or when mount bending occurs

[lock]

Yeah, I could definitely skip the two htd5m belts under heavy braking on my Trampa.

Here’s one of Kyle’s OneWheel prototypes (ref).

Looks like a 10mm htd5m belt, so I’m not surprised he switched it over to a chain drive. There’s also this example of a belt drive onewheel that didn’t work out so great.

I thought making one would be easy... a DIY OneWheel failure

[SwarleyAUS]

Yeah if I could work out a tensioning/idler system and weld the wheel pulley to the axle or integrate a keyway to stop it slipping, the 5m might be ok, but I think my motor is too small/high kv regardless. I really just cbf after 4-something years of trying.

[lock]

The floatwheel guy seems intent on using a 63mm motor, with a 5m belt. I’ll be curious to see how that works out. Be great if it did as you’d be able to get much higher reductions, but I still have my doubts.

This project started back in 2018, so I totally get the CBF factor. I’d box it all up from time to time and forget about it for a year. It’s the kind of thing that is meant to be fun, so if it’s not stop doing it, well that’s my thinking anyway. That Fungineers build will work out awesome!

[Titoxd1000]

This is such an awesome project… Have you considered using a 2 stage reduction via an additional jackshaft. You could use a 4:1 reduction using 1.5 mod gears. Losi has some really nice straight cut gears (pinions are 8mm). Then you could increase your kv closer to 200kv

[lock]

Thanks!

So I see two ways forward; a much bigger motor with around the same kv, or a two-stage reduction with the same sized motor but higher kv. Gears make the most sense for the first stage, mainly due to packaging, but also two steel 1.5mod gears seem pretty solid. Also, torque on the first stage is much lower than second. Definitely thinking about it.

The bigger motor will be tough packaging wise (thinking 80mm to 107mm), I’ll need to raise the rear footpad (higher cg = bad on onewheels), and it’ll stick out the bottom even more. Will need new motor mounts. This bigger motor is a bit more exotic (single source/ $$$) than the 80100 which are everywhere. It’s also double the weight.

The two-stage reduction should be easier to package. Will need to design and machine a gearbox setup. More mechanically complex, but would probably still be lighter than the bigger motor solution. I think it’s the more logical solution.

[Fosterqc]

@lock

The bigger motor will be tough packaging wise (thinking 80mm to 107mm), I’ll need to raise the rear footpad (higher cg = bad on onewheels)

Damn no kidding At first I was thinking you could make a weird stepped footpad and mostly stand close to the wheel.
Two stage reduction and ~63mm motors if it could work would appeal a lot more to the FM riders looks wise. I think these funky ow designs will be a fun thing for people to mess around with when getting into vesc boards.