Does anyone know if it’s possible to buy POM gears somewhere?
This is the problem with gear drives made in small batches by small vendors, who sometimes run their businesses single-handedly.
I have a 2-stage gear drive from E-TOXX. It’s a disaster: his workshop burned down completely. All that’s left is a PsychoFrame and a custom-made electric go-kart (which he’s trying to sell, by the way). It’s a real shame because Jens was always incredibly innovative.
Anyway, 20S voltage and high current are pretty rough on POM gears. I already destroyed one because the helical gears on the intermediate stage misaligned due to the thrust forces.
When the current gears wear out, I have no replacement option and will likely have to replace the entire transmission, with no alternative currently available with a 1:15.625 gear ratio.
That’s why I’m wondering if there’s a service that can machine gears from POM, or even better, make the same ones in metal?
Your best bet is probably to try to see if you can get an stl or something from the original person, make one yourself, or work with someone else interested to make one, and then use a machining service to get some made. These parts usually aren’t particularly complicated to reverse engineer. I’ve never had gears specifically machined, and that may complicate things because cutting gears usually uses tooling beyond a simple mill and lathe, but larger places will likely have ways to make common gear teeth.
Another option may be to try to find a gear elsewhere with the correct specs, like pitch, pressure angle, and helical angle, and then have it modified or an adapter created to use it for the purpose. With straight cut gears, where you don’t have to worry about the helical angle, a lot of things use the same pressure angle, afaik, so it isn’t too hard to find things that work as far as the teeth. I don’t know if the helical angle is also fairly consistent, and I’ve never actually tried to adapt gears intended for something else. I’ve looked into it a bit, though.
POM straight cuts should be easily doable on a 3 axis mill, steel would very likely need 4 axis and/or very different tooling. I’m pretty busy until I launch the aluminium race chassis probably closely after esk8con time but after that I should be able to help out making POM straight cut replacements if you can send either the design file (stl or step) or a gear that I can model off of. Or maybe just dimensions and we can do 3d printed revisions until fit is good. Sourcing hardened pinions might be a bit challenging though, would likely need to buy at least 10 custom made.
as @chr1spe said, get all the stats from E-TOXX. Helical gears like that require hobbing, which is more difficult than straight cut gears but I don’t think it’s impossible for this group (you can get used hobs on eBay for small money).
I feel like Herringbone would be a really good upgrade, eliminate the axial(? Thrust?) force. I haven’t a clue how to cut a herringbone but I could see where you could hob two Helicals in opposite angle and bolt them together to create a Herringbone. Or maybe that’s a double-helical.
Hi
I have production partners worldwide for my work (Very expensive drones)
They can make it very easy in reasonable price if it comes from me.
Try to get the file for it, if not we will have to look for the cad of the standard product and apply the needed CNC rework.
If you have a file you could have them 3d printed using maraging steel. Maybe even upgrade to herringbone or straight cut while you’re at it. I’ve been abusing a set for almost a year now without issue.
