Got chains? screw belts! - 3D model of flywheel sprocket mount for 04B30T sprocket

I would think so but I can’t say for sure. Like I said, I got my chain and motor sprocket from Conrad.

Anyone know of a source for sprockets in the US that can handle custom bore requests?

I dropped a few drops of “Squirt” on an old aluminium motor mount to see and feel the solidified state of the lube. It definately feels like wax but just a bit more creamy - I was able to smudge it around a bit and it did´nt feel sticky at all. So I don´t see a reason why I should prepare my chain in hot paraffin wax at the moment (BIG YAY!) I do believe that my chain will stay fairly clean with this lube now that I got to see and feel it :grinning:

I´m also thinking about cleaning my bearings and replacing the bearing grease with “Squirt”. If this stuff is really good then it could save me a few watts that I else lose to friction/heat and maybe potentially increase my range. I´m also hoping that my bearings and wheels stay cleaner since the lube I used tended to leak out and attract a lot of dirt. The watts I´ll gain will probably not be that dramatic but hey, a few watts here…a few watts there…who knows right?

Here are a few pics of solidified “Squirt” under room temperature. I just used a toothpick to ilustrate the consistency of the lube. Here ya go…

@Jmding I dug around to find a source in the US (well, at least they have their HQ in Charlotte, NC - USA) here´s what I found. They have a 05B sprocket with 30 teeth which is just flat (without hub) and it comes with a 10mm pre-drilled hole check it out here (hole/shaft diameter varies with the amount of teeth your sprocket has)

Get some metric step up drill bits like this if you have access to a drill press and drill a bigger hole to suit your needs. A 20mm bore is juuust enough for a Caliber II and Paris hanger but I´d at least drill a 22mm hole. I could´nt get through 15mm of steel on my first sprocket which had an 8mm bore. It was just too much for my drill bits and they got dull pretty fast (that´s when I decided to purchase a pre-drilled sprocket and save me time and troubles). You may have a good chance to get through a few milimeters of steel before your bits get dull. Don´t forget to lubricate your bit and choose the right RPM for steel on your drill.

hope this helps

Any thoughts on iso 04b vs ansi #25? I imagine for you 04b is much more available, but it looks to me like the #25 might be a tiny bit beefier and maybe a little more reliable?

A 04B chain has a tensile strength of around 300kg. I’m pretty sure that a 04B chain will suffice. I think that we never really generate so much force on a street board. The moments where high tension is generated is when accelerating or braking. Cruising will have lower tensile loads.

I assume that the tension while accelerating is at it’s peak is when the board is at a complete standstill. As soon as the board starts moving the tension on the chain decreases. I think that other components such as motor, (v)esc or even batteries will fail due to increased amp demand before you actually reach 300kg tensile load on the chain (btw. 300kg is not even the max. load the chain can take so you’ll have to generate more than that to break the chain.)

It’s probable that the same applies when we hit the brakes. As speed decreases so does the tensile load. So in a scenario where you’re going very high speeds and you hit full brakes you’ll likely get thrown off your board before your chain fails.

So, that’s why I think that the issue with chains is not the tensile strength (well, starting from a useable tensile strength of course. In this case 300kg) but rather it’s mechanical durability.

The question is not “is it going to fail?” but “when is it going to fail?”

So, now that begs the question “which material/steel is the best for this application?”. I can’t say any facts about the different materials that are being used maybe someone else can elaborate on this matter.

I just read that a #25 chain has a tensile strength at around 480kg. That is a whole lot more, more than a 3rd that of a 04B chain. So you’ll be without a doubt be on the safer side when it comes to tensile strength. But I’m convinced that the material used, steel vs stainless steel…hardened steel etc. will be the determining factor how long your chain will hold. Is a softer steel better for the longevity or will a harder=more brittle chain be the better choice? I think a “softer” steel will withstand the vibrations better than a “harder” steel that occur in this application. I imagine a brittle chain could “snap” due to loads that weaken the material whereas a softer steel may start to stretch as it weakens thus making a failure not so dramatic in comparison. Take a look at a katana sword for example. The cutting edge is a brittle but of a more harder steel. Since it’s prone to break the rest of the sword is made with a softer steel to prevent the sword from shattering. Makes sense to me to apply the same logic to the chains we want to use.

Sorry for the long post but I was thinking a lot about this matter. I’m grateful for any information, experiences or thoughts about chains in our application and I’m sure so are other .

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Yeah, hardened teeth vs not hardened for example. Tbh, I think the most likely mode of failure will be corrosion and thinning metal due to wear. That is to say, chain drive should effectively be infinite life.

I’m a little worried that our drive sprockets will be too small, 9 ish tooth sprockets with only 3-4 teeth engaged. Not sure if that would be problematic or not, but suspect not really

I went completely away from metal drive sprockets - they just require too much lube diligence to be practical. I went over to POM (Delrin specifically) and have never looked back.

To this day I’m amazed that no matter how much power I push through what is essentially a plastic sprocket I’ve never broken one and see no indication of wear.

The lube, in this case, is for the chain joints, not the chain-cog interaction, and therefore is much less critical.

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I agree, material wear is the “enemy” here. I also agree that the drive sprocket will suffer the most from wear but I don’t think it’s prone to total failure. I’m sure the wear will be audible when it occurs as tolerances increase and cause the chain to “slap” around. Second to wear down will be the chain and last the wheel sprocket.

I think the only way to know for sure is to check, let’s say every 500km, and see how much wear has occured on the whole drive. I’m not too worried about corrosion especially in summer but corrosion protection will be an issue when it gets wet. Maybe a chain drive cover will be needed in wet conditions as an additional protective measure.

I’ll give that a thought when I have the need for it (I don’t enjoy riding in wet conditions anyway).

I wonder if 3d printed wheel (or motor, but let’s start with wheel) sprockets would be viable. I’m surprised as well that delrin drive sprockets hold up.

Do you have a source for delrin sprockets? My Google fu is lacking.

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Delrin drive sprocket? Never heard or seen one before. It’s interesting that it’s holding up.

@DougM Where did you get it from? How long has it been working? How do you ride? agressive? moderate? Ya got hills in your area?

edit Jmding beat me to the question on where you got your sprocket from.

Just asking cause I’m curious how a plastic drive sprocket can take that load…I’m impressed. I can imagine that also brings the dreaded noise down a bit? I don’t mind the noise but it did get the attention of a few dogs. That was not such a biggie with my belt drive.

@Jmding I could print a wheel sprocket given time - for science of course. I’m just in doubt that PLA or ABS is up to the task. I think PLA is too brittle. Carbon PETG might work but my printer will require upgrades for that material.

Looks like sdp-si stocks delrin and fiberglass/nylon composite sprockets for $5. Killer!

Why not straight petg? I think if we kind of “hack” the slicer so the Extrusion orientation is radial (rather than going concentric after clearing the teeth), it could be really strong

I think the latest version of Cura can already do that if I’m remembering correctly.

It looks to me like it can handle linear and concentric, but not radial. Shouldn’t be too hard to hack, you could cut a n-tooth sprocket into n pie-slices and position then together with 0.01mm air-gap between them, or something like that.

image

Man, I got to get all the other parts in so I can start experimenting with this

you mean hacking the gcode?

I really don’t mind the noise but if a printed sprocket is mechanically tough enough and is quieter on top of that then it’s definately a plus.

damn it…now I seriously have to think about upgrading the heatbreak for my hotend so can finally print carbon petg.

Not hacking the gcode, but finding a “hacky” workaround that forces the slicer to slice the shape with a more optimal extrusion orientation. I’ll draw a picture later on by what I mean.

btw, i dont think carbon petg would help much:

adhesion is worse than standard filaments, and I think that is going to be the bigger problem with printed components. Its so “easy” to print one in regular PETG to start, we should try that out and see if it fails.

Sprockets from gears and sprockets arent hardened Its basic steel so pretty easy to drill it

You can buy a steel one for 4£ 24t on gears and sprockets

wheel sprocket 3d print concept, with a “hacky” way to force the slicer to lay the filament down radially. Torque load will be perpendicular to extrusion orientation so you dont have to rely on extrusion-to-extrusion bond strength.

image

You’re gonna have a ton of abrasion issues with that kind of tooth profile.

Normal metal sprockets have angled edges of the teeth to help with slight misalignment. With flat sides, any kind of imperfection will lead to the edge of the chain digging into the side of the sprocket and wearing off material.

Also, that does not look like the proper #25 chain tooth profile. You’ll have more wear issues with the chain rolling off of the sprocket from the pins catching on the backside of the tooth on the loose side of the chain that isn’t under load.

Even aluminum sprockets will wear down fast, so you’re going to need very good alignment.