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Cheap Ass 6x2 Pneumatic Belt Setup. 3D printed Pulley/ Vex Versa Pulley. Files available

wheels
pneumatics

#41

May I suggest putting big washers for each bolt and nut, or just use flanged bolts and nuts. that will give you good compression force without destroying the plastic.

The way I dealt with it is: I set the electric drill to a certain torque and tried it on a piece to make sure it doesn’t damage the plastic. Once that torque setting it known, you can reliably use that every single time.

BTW, what is the approximate cost of 3D printing in cu inch for you?


#42

Washers would be a great idea, I just didn’t order any with the bolts as I eventually got a feel for how tight to screw the bolts.

My roommate has a fairly nice 3D printer, so he’ll pump out prints so long as I have filament. I used PETG filament and it’s $25/kg for a quality roll. Comes out to ~787cc of volume, but that’s usually higher since I used a 50% infill.

4 full wheels and a pulley probably take a little under a kilogram of plastic, however I’m unsure since I went through 2 rolls printing prototypes and the final wheels for this project of mine :sweat_smile:


#43

I’ve just ordered a set for my next build… rude not to at that price!!


#44

looking cool!
Reduce the gearing a bit that the wheelgear shrinks a little for more clearance, look for someone CNCing that thing and i´ll hopp on board for a set :grin:


#45

you want to shrink it even further? I find the clearance quite good for 6inch wheels.
Limiting factor is actually the motor being too close to the hanger. It is so close now that they are almost touching each other - even with a 5065 motor.


Complete noob first time mountainboard build
#46

since i saw @Nowind ´s reduction gear 10 to 40 teeth, everything else looked so bulky :sweat_smile:
But you´re right, this inner gear brings the motor too close to the hanger…


#47

Hey mate are the dimensions of the hubs and pulley set correct as per the real life product, I’ve notices the slot for the bearings measures 24mm not 22mm like skate bearings.

Do the designs need to be scaled?

Other then that the system looks good, I may have to try and see if they will fit with dual SK3s.


#48

Depending on what you’re 3D printing and the material used and how accurate your printer is, you have to make the hole slightly larger than 22mm as you don’t get that perfect precision you can get with a CNC machining out aluminum. I’m not sure if 24mm is too much in this case, however for my design I ended up making it a 23mm hole for the bearing so that you could press fit them in and they would be tight. The first one I made where the dimension was 22mm I ended up crushing the plastic trying to press fit the bearing in.

However these are not my files, so I’m unsure of why he went with 24mm.


#49

Have you gotten the chance to put some miles on that 3D printed direct drive? I’ve always been terrified having the forces on 1-2 plastic teeth at a time rather than a whole belt :sweat_smile:


#50

Designs shouldn’t have to be scaled. Let me check the bearing slot dimensions again.


#51

They are indeed 24mm in the design(which I created by measuring the parts with a calliper). I don’t have the wheels with me right now so can’t really say if they use a different bearing or not, but rest of the parts are dimensioned right and I have tested that they fit perfectly.


#52

No unfortunately not - I printed the second gear though and will try to assemble it tomorrow. Wish me luck!


#53

https://www.aliexpress.com/item/Tire-and-wheel-hub-200X40-with-a-Bent-Angle-Valve-Stem-Electric-bicycle-tyre-Electric-Scooter/32891081000.html?spm=2114.search0104.3.321.1d677629YkQGxN&ws_ab_test=searchweb0_0,searchweb201602_5_10320_10065_10068_10843_10547_10059_10548_10696_100031_10319_10084_10083_10103_10618_10304_10307_10820_10821_10302,searchweb201603_16,ppcSwitch_7&algo_expid=e2584da4-9f42-439e-ae46-58e3ac7f32ff-47&algo_pvid=e2584da4-9f42-439e-ae46-58e3ac7f32ff&priceBeautifyAB=0

anyone tried these? looks like they already come with holes for bolts.


#54

The whole reason of using these aliexpress 6x2 wheels is:

  1. because they are aluminum
  2. 6x2 is probably sweet spot in terms of size
  3. 6x2 has proven to be reliable.

But these might just be good. Mounting a pulley would be pretty similar to the design I have.

Maybe people more experienced with pneumatics can talk about why this would or wouldn’t work.
image


#55

ah damn, i overlooked the dimensions. I searched for 6 inch wheels, these are sadly 8 inch.


#56

Those come out to roughly the same price with shipping as the other ones (at least to the US that is).

They look like they could totally work. @mishrasubhransu Did you say you have to modify the bearing hole on the 6x2’s you listed above? I remember reading about it on the other topic but I never really understood or got a clear answer on it.


#57

No I didn’t have to modify anything, just added 2 3Dprinted parts(the adapter and the pulley) and three 45mm M6 screw. It came with its own bearing. I am just saying that they might be using bearing with 24mm OD. But I am not sure, left the wheel at home.


#58

Alright after doing a little riding, I’m running into a significant issue with the pneumatics I’m testing, battery life. On the original hard wheels I have, I could go ~18 miles on full battery. With the pneumatics I’m testing right now, this range has decreased to about 3.5 miles. There are three main issues I think this stems from.

  1. I’m using pneumatics. I already know there’s increased rolling friction and was expecting to lose about half my battery life, but not 80% of it.
  2. The pneumatics have a really aggressive tread and they’re very flat at the contact point (all 1.5 inches of the tire is on the ground).
  3. Poor design in my hubs. It could very well be that my wheel hub designs are having an unforseen impact on this that I haven’t figured out.

For my commute, I need my board to safely go 6 miles (which is why I was hoping it would stay in the 8 or 9 mile range). I’m trying to figure out if I should drop the money on a bigger battery, scrap the pnuematics I was working on and go with one of the other designs above for scooter tires, or some other unseen option I haven’t thought of yet.

Thoughts?

-Also, it may be worth noting that if I spin the wheels with my hand, they roll forever (good bearings working like they should). However, when I push myself on the board and roll to a stop, I stop after only about 5 feet of free rolling since there’s so much friction.


#59

So basically the quality of rubber+tire is unsuitable for speed. Well, you tried. Time to get those cheap true pneumatic wheels :smiley:


#60

I guess I have some super meaty all terrain wheels I can sell🤔 they work great and get up to speed etc, but the decreased battery life is a hit I can’t take😭