belts: Gates vs Optibelt ?

[marka-ee]

I'm looking at various prices in the EU for toothed belts and I'm noticing that Gates is almost double the price of the more local Optibelt type. Does anybody have experience with Optibelts as far as durability, etc?
I was looking at pricing on www.zahnriemen24.de , I'm not sure if it's the best or cheapest place to buy either.

 

[scianiac]

Unless you really need the added load performance of a fancy special tooth profile or a special material (carbon fiber) I don't see any reason not to go with whatever reputable brand is reasonably priced as they will probably all have quite good durability as long as they are used correctly. The killer though is often the pulleys which can sometimes be super pricey if you don't make your own. The design of the system will have a much larger impact on the performance and durability than the actual belt brand.

This may be helpful: https://www.pfeiferindustries.com/d...th Profile and Pitch (Interchangeability).pdf

 

[marka-ee]

I don't think I need any fancy belts. Perhaps even a PU belt would work as long as it has Kevlar fibers or steel fibers in it. The only sprocket I would need would be the motor side. The other side on the wheel would be very large diameter, almost the same diameter as the rim if I can make it fit. 3D printed as per some YouTube videos show. Since the driven pulley is almost the same diameter as the wheel, this means that the tensile strength of the belt driving it is relatively low, which is a big plus. That's why I think I don't need anything too fancy for the belt.

 

[harrisonpatm]

The other side on the wheel would be very large diameter, almost the same diameter as the rim if I can make it fit. 3D printed as per some YouTube videos show.

I'd like to see more info on which videos show people 3d printing their rear drive sprockets, as well as how you're printing a rear sprocket large enough and strong enough.

Not knocking it, I'm genuinely curious. I love 3d printing unconventional things.

 

[amberwolf]

I'd like to see more info on which videos show people 3d printing their rear drive sprockets, as well as how you're printing a rear sprocket large enough and strong enough.

Did you see this? (different type of system, but....)

Ring gear / drone motor Ebike prototype

For those interested in low weight motors for Ebikes, I've used a drone motor (P60) and a (mostl likely) innovative gear reduction using : - a large ring gear (module2) attached to the rim - an intermediate external/internal freewheeling gear - a spur gear gear module 1 connected to the motor...

endless-sphere.com

 

[harrisonpatm]

Did you see this? (different type of system, but....)

Ring gear / drone motor Ebike prototype

For those interested in low weight motors for Ebikes, I've used a drone motor (P60) and a (mostl likely) innovative gear reduction using : - a large ring gear (module2) attached to the rim - an intermediate external/internal freewheeling gear - a spur gear gear module 1 connected to the motor...

endless-sphere.com

View attachment 348406 View attachment 348407

Indeed I did, though I was more curious about a more traditional pulley for a rear wheel.

Plus in the above post, he said:

Gears were cnc cut in FR4 material (expoxy/glassfiber) using small end mills (1mm/1.5mm diameter).

So not printed. Still very cool.

 

[amberwolf]

Somehow I missed that about the gears being cut that way, but I guess that would be a lot stronger than most of the 3D printed stuff.

I wonder if interlocking printed segments of pulley could be used? I have a feeling that their compressive strength as a ring for a belt pulley would be stronger than their outward strength as that type of gear, but I don't know which printable plastic would be better for it.

 

[DaLanMan]

I am curious how resistant to smut and dirt is?

 

[harrisonpatm]

I have a feeling that their compressive strength as a ring for a belt pulley would be stronger than their outward strength as that type of gear

This is what I was thinking too. Traditional gear teeth 3d printed would be prone to breaking off. Whereas a belt pulley, that's basically just being compressed, should have decent strength. if you look elsewhere online, the e-skateboard DIYers like to 3d print their belt pulleys, since they're relatively small. So I wonder how well it'll scale up.

Looking forward to hearing from OP regarding his experience in the matter.

but I don't know which printable plastic would be better for it.

If it were me I'd go with PLA+ (which might deteriorate when exposed to UV, but still quite strong) PETG-CF, PA-CF. If you have a printer that can handle it, PC would probably work well too.

 

[harrisonpatm]

I am curious how resistant to smut and dirt is?

Resistance? Not sure. But I suppose one advantage of a plastic-based sprocket is that it won't be subject to rust and corrosion like a metal sprocket.

 

[marka-ee]

Indeed I did, though I was more curious about a more traditional pulley for a rear wheel.

Plus in the above post, he said:

So not printed. Still very cool.

, which is less noise prone than direct gear.
Also, this video is very good.

I like the design Tom did on the second video. He has gone through many revisions. Although I'm thinking of somehow attaching it to the rim instead of the disc hub because I want to go as big as possible. The problem is that I don't know yet if I have the clearance for the belt without using too many idler pulleys. By using an extremely big pulley on the wheel, this lends itself to a slightly bigger pulley on the motor and that all translates to less noise because you're not having to mesh so few teeth.

 

[Chalo]

Although I'm thinking of somehow attaching it to the rim instead of the disc hub because I want to go as big as possible.

If you are cool with committing to a single combination of hub, rim, spoke count, spoke gauge, and lacing pattern, you could make the sprocket to interface with the spokes rather than either the hub or rim. And that would give you latitude to place the belt line where interference with the frame is minimized.

 

[marka-ee]

If you are cool with committing to a single combination of hub, rim, spoke count, spoke gauge, and lacing pattern, you could make the sprocket to interface with the spokes rather than either the hub or rim. And that would give you latitude to place the belt line where interference with the frame is minimized.

That's true. Now that I think about it, I could create the 3D model so that it fits the angles of the spokes exactly and also the curvature of the rim so that it is a very snug fitting system. Then, maybe even simple tie wraps, multiple per spoke, could be used to fasten it. However, I'm still wondering about preventing the downward motion along the spoke towards the axle, so I may still need to have a small screw that attaches to the rim to prevent that motion. The angles of the spokes would help prevent excessive motion, but I wouldn't rely on that alone because I need to have pretty much zero motion.

 

[Chalo]

That's true. Now that I think about it, I could create the 3D model so that it fits the angles of the spokes exactly and also the curvature of the rim so that it is a very snug fitting system. Then, maybe even simple tie wraps, multiple per spoke, could be used to fasten it.

I think if the notches closely fit all 16 or 18 spokes on that side of the wheel, its movement would be constrained enough that 3-4 zip ties total would be all you needed to retain the sprocket in the axial direction. This assumption presumes that the structural hoop of the belt sprocket would be stiff enough by itself to maintain its round shape under the belt's working tension.

 

[harrisonpatm]

Thanks for those links, I'll check them out. I need to finish watching these two videos, but they also are interesting resources in this topic:

By using an extremely big pulley on the wheel, this lends itself to a slightly bigger pulley on the motor and that all translates to less noise because you're not having to mesh so few teeth

I like this train of thought as well. My last conversion necessitated a 7:1 ratio, and therefore a 12-inch rear chain sprocket. Which is ok, but noisy. So I am considering a pulley-belt DIY upgrade, and I'll be following your process.