I’ve been focusing a lot of time lately into two things. Finding permanent work: Check! So now I’m on to the next part: Developing a pneumatic hub motor based on my experience of working with hummie.
The goals of this project are simple:
- Supports 6-inch, 7-inch, or 8-inch tires
- At least 2000 watts con per motor
- Easy swapping of tires
- As compact in width as possible while still achieving the performance required (67mm in this case from tip to tip)
Currently, the design uses a 6430 stator which I have found a supplier of.
Speed wise, looking to hit around 40 kv. This would give the following top speeds roughly:
- 6-inch: 26 mph
- 7-inch: 31 mph
- 8-inch: 35 mph
Where I need the communities help
First off, I need experienced view points about trucks:
Which trucks do you like and why?
What is the best wheel case to you?
RKP/TKP/Spring truck like trampa?
Second piece is I’m wondering if there’s any expert lathers that could assist in machining 2 or 4 prototypes? Getting the first couple to assure everything is correct is the most costly part as china charge an arm and a leg, plus they are not going to be doing much for the next month.
The hope is to bring these to market by no later than the end of this year. Hard to comment on pricing, but aiming around $700 for a 2wd with front wheels and both trucks. This might be hard though so we will see.
Thank you for checking it out!
What about doing something similar to carvon first iteration, motor partially inside the wheel, but far off back that the valve is not in the way and you can use a larger diameter stator?
This is a pretty decent size stator. I’m personally more attracted to hub motors than dd setups.
Looks sick!!! If you are using something similar to hummies bearings I would make sure they are sealed - if you are thinking off road applications. Those huge inner bearings do not like dirt and sand haha.
Looks Awesome! And congratulations on your new job. Is it an engineering job?
As for my thoughts on the hub motor, I would suggest that you only focus on the rear wheels and trucks to start with. I like wide trucks with pneumatics. Pretty happy with TB218. You can start with iterating with 3d printed parts even before you machine anything. Try to get better deals from the supplier. You know how cheap hub motors are these days (the skull board hubs with 105 tires and both trucks were selling for $180). You can probably use those prices to negotiate better. I think that’s it.
Nice! You could also try to bring that to the scooter industry. Innovation is not keeping up with the laws . There are no 9in x 3.5-4 wheels that are electric for scooters (standard electric wheel chair mobility scooter) aka cheap . Make something that killed 2-3 birds ? I always felt the scooter, and skate board were a close industry. Keep innovating. It’s like the dawning of the auto industry. There were many “great ideas” but only few got to keep them.
No, unfortunately, it’s not an engineering position, but when I get to full time, the pay is very good for a single person, lol.
The front truck will be easier this time around. Not having to produce wheels from the ground up is a big plus.
I’m not sure how much it’ll cost to machine, but it’s hard to compare these to anything else on the market. I will be focusing on quality parts. Hoping to use n52sh magnets for example. I’m planning on building these in house, like the hummie hubs.
Yeah for sure you’ll use quality bearings and magnets but machining cost makes sense to remain close. So just asking to bargain well citing those examples.
Oh I will look. It’s a tough cookie to crumble. I remember with hummie, it took over a dozen places to get the prices he got today, which was pretty reasonable. The next best was many times higher. It’s not an easy game, and in this case, the motor diameter is much larger, so we’re talking about 4 times as much steel in the first place.
The issue is the magnets, magnet glue, and motor winding epoxy are not cheap. And stators, we’ll see.
forgot about the squared law for a bit.
yea, I’m starting at 110mmx110mm Hummie hubs are starting at almost half of that. So almost 4 hummie hubs could be made from the same block. That will be the biggest issue imo of getting these affordable.
Have you considered aluminum as the build material or at least the majority of it? All hub motors wheels are usually aluminum, like the ones used on scooter. The shock and fatigue from the vibration it’s much less with pneumatics, so you should definitely consider it. There is no point in over engineering if it’s not needed.
Would this be an open source project? Would you post your parts list and any CAD files? I am a computer science / engineering student and I have long wanted to do a project where I construct my own motor. I have access to the machine shop at my university with a cnc, metal lathe and pretty much any tool I could ever need.
If you want to keep the IP behind this project private I totally understand, but I figured it is worth a shot asking for the designs as you finish them.
There is a different different opensource hub motor design on this forum. Give it a search.
I dont have a cnc lathe and I haven’t used my manual lathe long enough to do real parts on it but if you need something CNC milled I can help out. For prototypes I’m pretty sure a milled hub will do but you will ofc get better accuracy with a lathe ^^ Shoot me a PM if you don’t find another option.
@evoheyax I’m really glad you’re doing this, after our hangout at the renegade weekend I’ve been waiting to see what you’d do with all the knowledge and experience you’ve got. Congrats for getting to this point! I’m excited to see how this turns out.
I’m also curious about how the heat generated by a hub motor might impact the integrity of a tire (vs a urethane sleeve like most hub motors).
Okay what is the benefit of a hub driving pneumatics that are large in diameter. You can already do with direct drive and 6” wheels easily. Everybody is doing large pneumatics. Now let’s talk about a hub motor driving pneumatics that are wide and say 105mm in diameter like a skateboard wheel. I want to be low to the ground and have a super smooth ride without all the noise/weight of belt driven motors.
In terms of benefits vs direct drive, one big benefit is ease to switch tires and tubes.
Direct drive: Remove a nut, then pull the wheel off of an adapter, then unscrew the hub split it in half, and do the replacement
Hub Motor: 7 screws, plate comes off, and tire and tube come off.
It’s also simpler in construction. There’s no adapter, the wheel locking mechanism is built straight into the motor.
In terms of DD motors, I haven’t see any 40 kv DD motors on the market. This is a problem as I stated before because the top speed will be too high, resulting in weaker torqure than a motor with a reasonable top speed (i.e. lower kv).
It’s also way more compact than a DD motor. By adding adapters, motor 100% outside of the wheel, you lose space. In this design, 80% of the motor is actually inside of the wheel. There’s a slight hangout for the turns on the ends of the stators and for bearings and the C-Clip.
So what do you get? Less parts (simpler design), easier to replace tires/tubes, correct kv (and thus, reasonable top speed), and more compact design that keeps almost the entire motor in the frame of the wheel, allowing for more stealth (this is the main reason many looked at hub motors over DD motors in the first place).
I just meant why make a hub with a big tire. Everyone has large tires already whether belt or DD. I own belt pneumatic, DD with urethane and belt urethane. I have owned hubs too. I would only use hub with pneumatics as the thin urethane is no good for smooth riding or longevity of the hub motor imho. I’m interested in seeing a hub pneumatic being done. Just wish someone would make it small in diameter as I want some drop but not major drop and want to be closer to the ground (not to mention having a giant wheel).
Have you though about doing a mix between hub motor and direct drive? Like a direct drive thats go inside the wheel hub aswell. Wondering why anyone havent done this yet, as it would result a lot more torque.