Versa Planetary v2 (3:1) Planet Gear Seizing

[Fusion_Clint]

We had a problem with a brand new 3:1 not fitting into the ring gear correctly. We had bought two so we tried the other one without incident. Swapped them out and the problem stayed with 3:1 not the ring.

I contacted VEX and they shipped a new one out ASAP and requested the bad one be returned (on their dime). New one works perfect.

Please stress to your students that if they don't go together easy and can be hand turned inside the ring gear, they may have an out of spec 3:1.

Contact VEX if you get some bad ones. Great folks and great service.

[OMGRobots1]

We have been having issues with 3:1 reductions as well.
One of ours was obviously made out of spec (one gear couldn't move at all, couldn't be removed from shaft) and the other was having binding issues.
We just used 4:1s, and they worked fine IIRC.

[cadandcookies]

Originally Posted by Fusion_Clint

We had a problem with a brand new 3:1 not fitting into the ring gear correctly. We had bought two so we tried the other one without incident. Swapped them out and the problem stayed with 3:1 not the ring.

I contacted VEX and they shipped a new one out ASAP and requested the bad one be returned (on their dime). New one works perfect.

Please stress to your students that if they don't go together easy and can be hand turned inside the ring gear, they may have an out of spec 3:1.

Contact VEX if you get some bad ones. Great folks and great service.

I just want to reiterate this. FRC suppliers (especially VEX/IFI, AndyMark, Rev) are generally very helpful if you reach out to them with a polite email. A lot of the people at these places are passionate about FIRST and want to see teams using their stuff succeed. The five minutes it takes to write an email to them can really help with solving many issues.

[Bruceb]

Had the same problem with a new 3 to 1 sent back to vexing haven't heard back except to send us a new one reading this I should test all the 3-1s I have I guess

[Jon Jack]

I'll start by saying if you think you have a problem, call (or email, prosupport@vexrobotics.com) us.

We have had a few reported cases of 3:1 gear kits having seized gears or being a very tight fit in the ring gear. In most cases of a tight fitting 3:1 gear kit it's a combination of the gear kit being toward the high side of the tolerance and the anodizing on the ring gear being a little thicker. This is easily solved with a run in.

I've seen two cases of gears seizing on pins. One was from a bur on the bore of the gear. The other was from a crooked pin on the carrier. I've yet to see any cases where the pin or bore on the gear were out of tolerance.

In some reported cases we've been able to fix the issue and in others we've replaced the gear kit.

Here are a couple recommendations I have if you have a tight fitting 3:1 gear kit:

1) Make sure there's no dirt or large debris on the gear teeth.

2) Run the gearbox in, lubricated, for 30-60 minutes. All gearboxes need to be run in at some point. In some cases (ex: the transmission in your car) they do the run in at the factory. However, due to the modular nature of the VersaPlanetary we do not have that luxury. Note: Lubricated does not mean packed full of grease. You can over lubricate a gearbox.

[bdaroz]

Somewhat on-topic here...

A question for the collective knowledge pool:

How much lithium grease is too much / how much is too little?

(Keeping in mind the v2 manual uses the term "liberal" -- some students will want to drown the gearbox, others will go the opposite route.)

We had a borrowed VP last year that was pre-greased (rookie year) and went out and invested in several this year, so we're looking to do it right.

[billbo911]

Ed,
Where were the seizes taking place? I assume a planet gear was locking up on the carrier plate pin.
As mentioned, lube is crucial, not only between the planets and ring but also between the planets and pins.
One other thing to check is if the pins are perpendicular to the plate. Any misalignment will eat the VP alive.

[Chris is me]

Originally Posted by bdaroz

Somewhat on-topic here...

A question for the collective knowledge pool:

How much lithium grease is too much / how much is too little?

(Keeping in mind the v2 manual uses the term "liberal" -- some students will want to drown the gearbox, others will go the opposite route.)

We had a borrowed VP last year that was pre-greased (rookie year) and went out and invested in several this year, so we're looking to do it right.

A good rule of thumb is to put on as much as you think you need, and then a little bit more than that.

I like to paint the grease onto the outer edges of the planet gears and spin it around, then add more and spin, etc until every surface has some visible grease on it. Then a touch more and assemble it.

It's not that easy to over-grease a gearbox.

[Mentor_Rick]

We have had the same issue with a 4:1 with proper lubrication. Found a burr on the peg and gear of one of the planetary gears

[JamesCH95]

A point that I observe many people missing when greasing VP gearboxes: every planet gear should be taken off its shaft and have the shaft/bore in the gear greased and have the bottom face of the gear greased. Packing the inside of the transmission with grease isn't enough to get grease where it needs to be!

I can easily imagine not greasing these areas leading to a seized transmission.