great project! will like to see if your gear drive is reliable in the future, btw l have wait almost 2 years for the
boardnamics dual gear drive and l bought one yesterday lol
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Update! 3D printed mock up and design finalisation
Hey guys I âve spent the last couple of weeks taking everyoneâs feedback on board as best I could, and I have made tweaks to the design. Iâve also been 3D printing all the parts and physically testing the assembly, Iâm glad I did! Because I identified some issues that would have gone unnoticed in CAD. What did people do before 3D printers, testing designs must have been a real pain!
Some of the most notable changes to the design are:
Increased the thickness of the motor mount plate. I designed the gear drive to be a thin as possible without sacrificing the gear width, however what I didnât consider is that the motor shaft would be too short (22mm), resulting in you not only having to cut the shaft down to size but also the keyway. In this design revision the motor shaft is 26mm long and the pinon gear utilises the full length of keyway making it stronger and removing the need to cut down the keyway as well as the motor shaft. This does have an advantage, as the drive should be stiffer now and resolves a concern @ShutterShock had:
Iâve also come up with a new wheel mounting method, I didnât like the way that the extended bolts just slotted into the gear drive hub mount before, and @sleepless has his concerns as well:
This new method uses custom round nuts as a replacement for the for the wheel hub hex nuts, and then the round nuts slot into the hub mount of the gear drive and everything is retained with the truck axil nut. I think this is a more elegant method and there shouldnât be issues with the bolts wearing through the hub mount like with the previous design iteration.
@jack.luis I have come up with a method using thrust bearings in that would make it impossible for the pinion gear to come loose from the motor shaft due to helical gear axial force; his method would also negate the use of Loctite retaining compound. However, it adds too much cost to drive and thus not really affordable for most eskate builders, so I might develop this idea separately as pro version of the drive.
I made other minor changes such as making the motor mount gasket wider, adjusting tolerances etc⊠but I wonât bore everyone with the details.
The 3D printed mock works quite well, ABS is pretty strong, but I will wait until the I have the first metal functional protype before properly testing the drives. I did have some issues cutting the neoprene rubber gaskets using my girlfriendâs Cricut Maker, itâs basically too stretchy for the drag knife to cut through it effectively. Iâm going to try laser cutting the gaskets or having some die cuts made, this is pretty much the only manufacturing detail left unsolved now.
The next step is to fully lock down the design, get the first protype manufactured and test it to see how it performs on a mountain board.
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Looking really good, nice work so far. I like your hub interface method, seems like it will work pretty well.
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Can you elaborate on this for innovationâs sake?
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Thatâs a really cool idea. 
could be even more simplified by just using the cylinder head of the bolts that hold the wheel together I think.
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So bolts go in from the back of the wheel hubs? Hmm thatâs an interesting idea. The bolt heads would have to be floating in pockets in the drive hub mount, otherwise youâd never be able to assemble. Could work. Still donât love floating though - youâll get wear unless material hardness is similar.
^ FYI, youâre going to get dirt and dust that works its way through the hub spokes into the gap between your truck mount and the hub mount. It might not make it into the drive past the bearing, but itâll accumulate there. Maybe nothing to change, but something to be aware off.
Whatâs the point of going custom round? This actually seems worse. If/when they spin, theyâre coming off with the hub when you try to change a tire. I like the embedded nut approach though. You could go square if you donât like hex. You could also find other ways to embed steel threads into an aluminum/composite hub mount - flanged nuts (installed from the boardside) or rivet nuts, for example.
On your hanger mount, please consider adding more mounting holes. Add them with 2 or 3 different, offset patterns, so your combined minimum angle of adjustment is very small. This will allow people to fine tune the ground clearance of their motors regardless of deck tip angle.
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Sorry I donât want to give too much away at the moment. Itâs not that innovative to be honest, Lacroix Boards already have a method of retaining the pinions in the Falcon gear drive using a circlip and spacer built into the pinion design itself.
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Thanks for all the feedback mate, this is very helpful 
I can imagine that happening, but there is rotary shaft seal in that crack between the hub mount and truck clamp, so dirt/water wonât get as far as the bearing and into the gear box itself.
I went with custom round because, I was concerned that if I used hex stand offs for example there could be alignment issues with the corresponding hex shaped holes in the gear drive hub mount. Whereas the round holes and nuts combo will be easy to align and slot in when you push the wheel on; the tolerances are tight to reduce movement and wear, but the holes have slight chamfer to help you guide the round nuts in. I donât think the round nuts will be pain when changing a tire, as one end is slotted so you just tighten them down with screwdriver; admittedly it would probably be advisable to use some Loctite as the original hub nuts are nyloc to prevent them coming undone.
Dude! Thatâs a good idea! I will definitely add in a set of offset holes to affectively double the adjustment resolution from 18° increments to 9° degrees.
I like this idea! If I could source bolts with extra-long heads then they could slot into the gear drive hub mount and I could use standard nyloc nuts on the other side of the wheel hub.
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Just use some M4 spacers. Or really any spacer that fits onto your bolts. For a quick mockup you could even use a stack of washers.
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Could be minimal if the correct tolerances are used. In that case the holes should outlive the drive. Also a bit of widening shouldnât matter that much, but thats depends to be seen.
whatâs the secret for getting hardened and ground gears for this cheap? Is it just volume? Even the stock gears of this kind Iâve seen online made by KHK tend to be about $200US for just a bull gear and pinion.
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Ordering in volume is pretty much the only way to get the price down, ordering a one off it always going to be expensive.
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Yeah, from what Iâve seen this tends to be the case. Its really unfortunate thereâs no other way of getting stuff like this for more justifiable prices. Itâs times like these i wish i had a friend with the equipment to do high precision gear cutting, hardening, and grinding, but alas people like that arenât all that common lol.
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I know itâs not one of your primary design considerations, but what do you expect these drives to sound like? From what ive seen, thoes that have been most effectvie at producing super quiet geardrives have opted to attain this noise level by using larger (i think around mod2) plastic helical gears. According to this info page by KHK, it would seem that the quietest gears attainable would be something like high precision ground helical gears with small teeth, high face width, and high tooth counts on both meshing gears. On paper this sounds reasonable enough, but I donât think Iâve ever heard anything using gears of this type in anything even remotely close to an eskate. I wonder how the sound of such gears compare to that of the high quality plastic gears used drives like the ones made by @NoWind and @3DServisas .
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Iâm hoping they will be reasonably quite as well as being super durable, but we will have to wait until I test the first functional prototype to know for sure. Hopefully soon 
As with all engineering designs, there are trade-offs one must make with their design choices:
Plastic MOD 2 gears
Pros
- Teeth large enough so you can machine them out of plastic like POM thus making them cheaper and easier to manufacture.
- Plastic gears are inherently quiet.
Cons
- Teeth too large to abide by minimum No. of teeth gear design rule:
z = 2/sin^2(α) = 2/sin^2(20) = 17 - Gear wears out eventually or snap teeth during high torque situations and thus the gears become consumable item:
Steel MOD 1 gears
Pros
- Teeth small enough that you can abide by minimum No. teeth gear design rule:
z = 2/sin^2(α) = 2/sin^2(20) = 17 - Steel gears should handle high toque situations and hopefully outlast your board.
Cons
- Steel gears are more expensive to manufacture compared to plastic gears.
- Steel on steel gear meshing could be noisy compared to plastic on steel.
Iâve heard good things about 3DServisas, E-Toxx and MOON M2 plastic gear drives and also Boardnamics M1 metal gear drives, so there isnât a right or wrong way of doing it.
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Update! Neoprene gasket manufacturing
Just a small update this time, Iâm still waiting for the metal parts to be machined.
I manged to find a method for manufacturing the gaskets out of Neoprene, these are the first prototypes I think they turned out real nice
Iâm experimenting with using self-adhesive on one side of the gaskets to hopefully make the assembly process easier.
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most breaks are from backlash or fast speed and impacts
also mod 2 gears are high pitch, and mod 1.5 have more of a deeper growl sorta sound (just what iâve found form riding the two)
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