pic: Team 3647: Off Season Teaser 1

[topgun]

Originally Posted by AdamHeard

I'd also recommend looking into the .25" face width 24DP plastic gears from SDP-si for the initial stage. They are DIRT cheap at ~$2, and mate great with the banebots 10T pinions (which are also cheap, and fit through the motor boss hole). All of Encore's gearboxes had an initial plastic stage of this size.

Could you have gone with plastic gears throughout the entire gearbox or would that not have the tooth strength?

- T

[Mk.32]

We are doing what Adam suggested and switching the first stage to the 40T plastic [delrin] gears. However the rest of the gears we are using WCP alum ones instead of plastic gears because we just can't find/get plastic gears with the hex bores. And we do not have the tools to do so correctly.

[AdamHeard]

Originally Posted by topgun

Could you have gone with plastic gears throughout the entire gearbox or would that not have the tooth strength?

- T

Without one fully knowing all the equations and factors involved in gear strength, it's REALLY hard to say, "YES!, X is strong enough".

I feel comfortable saying the 24DP 1/4" wide gears from sdp will hold up in nearly all initial reduction applications off a 500 sized motor (I have a slight concern about fully reversed stall torque under repeated shock loading, as Encore didn't have any systems running that) as Encore ran that setup all over.

It's also hard to completely characterize the loading; if you know the gearbox never experiences anything near stall torque except under initial acceleration that's a totally different loading case than repeated bang-bang high load shocks (like an arm, elevator, something getting hit, etc...). For further stages I'd recommend increasing the DP of the gears.

I feel that the FP gearbox is a GREAT resource to look at here. Those gearboxes have been proven to be absolute tanks (in terms of the gears). Numerous teams have run them as assembled, or by removing the gears and building about that. One could infer the worst case loading at each stage there by looking at the ratios, and comparing gear size off that. Maybe throw 20% margin on there to be safe.