Idiotic question here…
Mixing 3D printed gears with metal gears will destroy the 3D printed one, right?
Eventually, yes. But that’s not always a bad thing, some things intentionally mix metal and plastic gears to allow for planned failure modes.
I’m not getting strong enough spur gears for the open rc by @Daniel_Noree and I’m planing to replace the gears. I’ve found the pinion gear but not the spur gear. So, that’s why I’m thinking about mixing.
Some one in the open rc community just told me the same thing. I think I’m going with the mixing option
It depends on so many factors that the best bet is to either try it and see, or start by printing 2 gears so you have a backup ready. AGMA quality, surface finish, loads( stress), and speed will each have compounding effects on the wear.
@Joe_Morrison I’ve a really problem with speed. The motor I’m going to be using is 4300 kv at 3S lipo, so, at max it will be at 47730 rpm.
47730 is a typo, right? That’s an unreasonable speed for gears.
How rough edges are would surely have something to do with wear and tear for any gear of any material.
When you get it right, use green sand and cast it with aluminum.
When you get it right, use green sand and cast it with aluminum.
@Francis_Lee I guess this (double posting) means you are using the G+ android app too? I hate it when the app tells me it could not post and then it double posts or posts like 20 times. Grrrr…
Oh… I didn’t notice! Yeah, darn Android.
Last year Android was great. This year, Google maps, Google Music, and OK Google all have gone down hill! 
@Ryan_Carlyle no typo 
Actually no. If everything is sized for the load it is a quiet and self lube system. If the system is overloaded then of course the 3d gear will give up the ghost first.
A 3d printed gear is gonna blow up in spectacular fashion at 47,000 RPM. I probably wouldn’t feel good running one at 4,700 RPM, tbh.
@Ryan_Carlyle I should get a slow motion camera hahaha
@Ryan_Carlyle not tru at all. I’ve run my 3d printed gears at 38,000 rpm so far without issue. Best thing is print them in nylon for those speeds. But my pla test gears are still living. I run the extruder temp way up to to top of the range, and the bed temp to 110c when printing them. Keeping everything good and got makes layer bonding excellent. Also print the gears at 6 perimeter layers, 4 top and bottom. Makes the gear teeth themselves solid, and the gear body almost solid. If I have issue later when I bump the speed up, I’ll machine some aluminum gears
@brian_alley nylon printed hot and solid, alright, I can believe that. PLA? Hell no. Not for long, anyway.
Well, believe what you want, there’s always that one guy that claims things won’t work, he’s usually the guy to afraid to give something a try himself. I’ve got gears here that prove it works. Pla at 230c and 105bed, they might have 30 minutes on them so far. There’s no reason at the diameter they are it won’t work. If they were 6 inch diameter I could see a problem. Next I get time, I’ll run a video of them in motion. I don’t have a high speed camera though