Also posted to reddit.com/FRC
Wondering about SOP for gearbox run-in…
Andymark gearboxes(Toughbox, etc.) indicate a 30 minute run-in without grease.
WCP(specifically the WCP SS) does not recommend a 30 minute run- in without grease.
Thoughts?
We’ve done a 30 minute dry run for years with the KoP chassis, never had any complaints with respect to the robot performance.
I think the difference is aluminum vs steel gears? I don’t think AndyMark does anything with aluminum gears and recommend wearing in steel gears, where as WCP is almost always aluminum gears which you don’t need to wear in because it would wear away the coating on the outside of the gears.
This is what we have tended to do as occasionally we have steel gears with tight spots that running dry fixes.
This may not be correct though.
I’m not sure about the WCP gears, but I understand that the AM TB gears are made of steel granules that are pressed into the shape. If you look at them new, the surfaces have a bit of an orange peel finish. The dry run-in smooths the gear face surfaces.
Never mind - it looks like the AM steel gears are also now made from gear stock.
Gearbox run-in - #14 by josesantos
I suspect the WCP aluminum gears are cut from either billet or extrusion, and have a smoother finish particularly on the tooth faces.
…like…sintered?
I think they’re just machined steel gears.
Maybe Andy knows.
2 Likes
This has to do with the quality and profile of the gears. Wcp/vexpro gears In our experience don’t require a 30 minute run in. They’ll wear in over time, just make sure to grease them and go.
2 Likes
Lively discussion for a new thread, and thank you for the quick replies. It must be build season…
The tolerances on the shaft locations for the plastic-housed AM gearboxes aren’t quite as tight as they are on the WCP/VP gearboxes. The burn-in period compensates for that.
It’s a mild annoyance, but the gearboxes perform just fine if you follow the provided instructions.
Agreed. Every FRC scale robot drivetrain I’ve built or been part of building has been had AM Toughbox series gearboxes*. Not a lick of trouble with a gearbox that wasn’t user error.
* Six competition season robots plus at least another dozen practice, off-season, and non-competition robots. And not all of them used standard gear ratios. Original TB, TB mini, TB micro, TB 3 stage, TB 3 motor - I’ve built with all these, though the 3 motor gearboxes weren’t for a drive train.
2 Likes
Any gearboxes other than the Toughbox series, I would not suggest doing dry run-in. For those WCP gearboxes, grease them up right away. The same for pretty much any others, especially planetary gearboxes, which should never, ever, be run dry.
By the way, you might also want to look at using something other than the “raspberry jelly” grease that comes with the KoP drivebase. We use Mobil XHP 222 Special lithium grease on all our gearboxes. It’s probably overkill, but it does a fantastic job and once you’ve applied it the stuff doesn’t come off.
1 Like
I used to have Strong Opinions about their quality back when I was too arrogant to read the instructions…
3 Likes
This is typically used as bearing grease, which tends to be nice and thick so it doesn’t go flying or dripping out. Perfect for FRC transmissions really. I’d never thought about that, as red tacky is technically the correct stuff for open air gears, or gear oil in an enclosed gearbox.
1 Like
Always used red/ tacky. I wonder about some sort of testing/ side project but the reality is that would be a better off- season project.
Older AndyMark gears were listed as “cold-formed.” My understanding is that cold-forming doesn’t use powder, but is basically just beating a piece of stock with various hammers (dies, more technically) really hard until 1) net or near-net shape is achieved and 2) hardness spec is achieved.
For gear manufacturing, it looks like cold-forming looks a lot like hobbing, except that material is deformed instead of removed:
2 Likes
We started using it a several years ago because it was recommended for the old Banebots planetary gearboxes we bought that year (the ones that were built like bricks.) We found that it worked on our other gearboxes too, even open ones, because it’s made to stay on whatever it’s lubricating pretty much no matter what. And, of course, with the lithium content, it’s a fantastic lubricant too. We’re still using our original tube of the stuff, because once you grease a gearbox with it, you really never need to do it again.
Would you agree that technically almost all FRC gearboxes are open air gears? I can’t think of a single COTS gearbox that could truly be considered a sealed case.
What exactly is the issue with red and tacky? I’ve never experienced a failure or any abnormal gear wear when using it in the past 11 years of minimal maintenance and heavy use.
That said, we usually don’t complete the dry run in either. The drive train is just a little noisy during practice at home, then we change the grease out if we notice it is dirty with any gear wear before competition.
1 Like
There is some difference between an open gearbox, and one with a non-sealed case, and one with a sealed case. The first one can fling grease everywhere, the second will only leak if the grease liquifies, and the third costs a lot.
2 Likes
Unshielded gearboxes near the floor tend to pick up lots of gunk, too. It’s not kind to the gears.
So uhhh… Anyone know what happens if you don’t run in toughboxes? And instead just immediately grease and install them?
1 Like
so far they’ve always worked fine for us, that way