Wormbox drive trains

After watching the new EWCP and seeing Andymark's new Wormbox gearbox, I was wondering if anyone had any experience/thoughts about a worm drive, mainly for defensive purposes.

[Chris is me]

There are more efficient ways of a high reduction drivetrain, in my opinion.

The WormBox's best use looks to be something similar to the stage after an FP + AM Planetary in an arm gear train.

[Andrew Schuetze]

Originally Posted by SuperNerd256

After watching the new EWCP and seeing Andymark's new Wormbox gearbox, I was wondering if anyone had any experience/thoughts about a worm drive, mainly for defensive purposes.

Only if the game included a nearly vertical wheeled climb would that type of drive be appropriate. Too slow and real issues with no coasting mode for stops causing wear and tear on the drive.

[AdamHeard]

Originally Posted by Chris is me

There are more efficient ways of a high reduction drivetrain, in my opinion.

The WormBox's best use looks to be something similar to the stage after an FP + AM Planetary in an arm gear train.

1425 did a single stage worm reduction using a "high efficiency" 4-start worm in 2007 that was VERY clean and drove their center wheel on a west coast drive. IIRC, talking to them at champs the student who designed it said the spec on that gear reduction was around 80% efficiency.

I've yet to see another team use worms in drive well, but 1425 certainly nailed it in 2007 making a lightweight, pretty efficient, and darn clean/compact setup.

Here it is
http://www.chiefdelphi.com/media/photos/26656

[MrForbes]

I'd have to go out to the garage and look in the opener, but isn't the wormbox a two start setup? it's only 16:1 ratio so it's not as wildly inefficient as some folks seem to assume....and I'm pretty sure it can be backdriven....

[Jared Russell]

I could backdrive the Wormbox at IRI by hand quite easily, so I would imagine it is pretty efficient. While high efficiency is generally a good thing, it does mean that the benefits to a defensive robot's drive train are limited.

I would suggest looking into something like team 25's servo-actuated brakes if being pushed is something you absolutely cannot tolerate.

[Brandon Holley]

Originally Posted by Jared341

I could backdrive the Wormbox at IRI by hand quite easily, so I would imagine it is pretty efficient. While high efficiency is generally a good thing, it does mean that the benefits to a defensive robot's drive train are limited.

I would suggest looking into something like team 25's servo-actuated brakes if being pushed is something you absolutely cannot tolerate.

We did a similar brake setup with pneumatics in 2007. The idea was that if we were partially stalled going up a ramp at the end of the match, we could still get 15 points without rolling down it by having the drivetrain lock in place.

I wasn't on the team at the time, but the NUTRONs 2004 robot had a worm geared reduction on each of its 4 pneumatic wheels. The robot suffered from terrible instability for a number of reasons. First being 4 pneumatic wheels caused the oh so famous "bounce turn" we see less and less these days with the 6WD kitbot. The robot was also quite top heavy as it had a large extending arm and turret at the top of it. Often when driving around the field the robot would tend to teeter forward or back as it went from full speed to fully stopped. I'm thinking the extremely difficult to backdrive (not highly efficient) worm gears had something to do with this. As soon as the driver removed power to the wheels, the robot would literally stop on a dime.

I'll try to find some pictures to show you guys.

-Brando

[pfreivald]

I'd be afraid of shredding the screw under the stress of a pushed-upon drive train. I don't so much trust that plastic until I've seen it put to the test!

[PingPongPerson]

I know that 987 used a wormgear transmission for their arm this last season and it worked really well to lift their arm!

[DonRotolo]

I don't see this as a drivetrain component, but as part of an elbow joint. The output shaft would drive a small gear or sprocket to then drive a larger one attached to the moving arm. 16:1 on a CIM isn't enough - the arm would move too fast - but take another 4:1 or so and it'd be pretty close...