Our 2017 drive train

[Massako]

our main idea for this drive train was to increase cycle times for gears and to allow for a super maneuverable robot. Let me know what you all think and if you have any suggestions Thanks.

[Massako]

http://imgur.com/SD4SlQf

[Jared Russell]

Others who have implemented this type of drive in FRC have strongly recommended ensuring that your strafe wheel is on some sort of a suspension to ensure it receives enough normal force to be effective on imperfect floors.

[mman1506]

I'd suggest switching out those shaft clamps for 1/4-20 button heads with a washer in tapped holes on the ends of the hex shaft. Thunderhex stock comes pre drilled with the proper size hole for a 1/4-20 tap if you don't have a lathe. This will save some weight and cost. You could probably increase the distance between your wheels too which is always good thing.

[Massako]

Originally Posted by mman1506

I'd suggest switching out those shaft clamps for 1/4-20 button heads with a washer in tapped holes on the ends of the hex shaft. Thunderhex stock comes pre drilled with the proper size hole for a 1/4-20 tap if you don't have a lathe. This will save some weight and cost. You could probably increase the distance between your wheels too which is always good thing.

Thanks yea. We already have over 50 of those hex shaft clamps and as well as the hex shaft but no lathe. I would like to do that but for simplicity sake its much easier since we don't have a lathe. I really appreciate your comment though.

Thanks

[Massako]

Originally Posted by Jared Russell

Others who have implemented this type of drive in FRC have strongly recommended ensuring that your strafe wheel is on some sort of a suspension to ensure it receives enough normal force to be effective on imperfect floors.

do you know anyway of doing that that would be cost effective and easy to manufacture? That's the only reason we haven't adapted that and are ok if it is not perfect. it is primarily there for slight assistance with aligning with the gear lift. we have looked at some implementations of such a method but concluded it would be to difficult for our ability with manufacturing.

Thanks

[ollien]

Originally Posted by Massako

Thanks yea. We already have over 50 of those hex shaft clamps and as well as the hex shaft but no lathe. I would like to do that but for simplicity sake its much easier since we don't have a lathe. I really appreciate your comment though.

Thanks

The nice thing about thunderhex is that it already has the hole, ready to be tapped for 1/4-20. You just need to tap it. No lathe required.

[Massako]

Originally Posted by ollien

The nice thing about thunderhex is that it already has the hole, ready to be tapped for 1/4-20. You just need to tap it. No lathe required.

Ok thanks. I will discuss it with my team tomorrow.

[mman1506]

Originally Posted by Massako

do you know anyway of doing that that would be cost effective and easy to manufacture? That's the only reason we haven't adapted that and are ok if it is not perfect. it is primarily there for slight assistance with aligning with the gear lift. we have looked at some implementations of such a method but concluded it would be to difficult for our ability with manufacturing.

Thanks

You could try using a VersaDrop module. The pneumatic cylinder will act as a air spring to give you some suspension travel and you could retract it if necessary. If you add a secondary air pressure regulator you can adjust the air pressure until you are happy with the amount of force it pushes against ground.

[Kevin Sevcik]

Originally Posted by ollien

The nice thing about thunderhex is that it already has the hole, ready to be tapped for 1/4-20. You just need to tap it. No lathe required.

The other nice thing about thunderhex is it fits better in thunder hex bearings than hex does in hex bearings. And doesn't have off-center holes like many hex bearings. And the thunderhex bearings aren't likely to crack and split under shock loads like some hex bearings. And you can use round shaft spacers instead of hex, and....

[Joe G.]

Originally Posted by Massako

do you know anyway of doing that that would be cost effective and easy to manufacture? That's the only reason we haven't adapted that and are ok if it is not perfect. it is primarily there for slight assistance with aligning with the gear lift. we have looked at some implementations of such a method but concluded it would be to difficult for our ability with manufacturing.

Thanks

Built one of these back in 2008. I can absolutely confirm that you need this feature -- not having it basically wrecked that robot. Middle wheel was ever-so-slightly lower than the outer four, and it could not drive straight, in any direction, to save its life. In hindsight, we should have pulled the middle wheel out after the first match and never looked back, instead of trying to fight it all event long.

Easiest and most foolproof way I can think of to do it COTS would be a VersaDrop module with only one wheel, spring loaded downwards. Alternatively, you could try building something like 148's decadrive center module out of a series of versablocks.

[Thingem3376]

Originally Posted by Massako

do you know anyway of doing that that would be cost effective and easy to manufacture? That's the only reason we haven't adapted that and are ok if it is not perfect. it is primarily there for slight assistance with aligning with the gear lift. we have looked at some implementations of such a method but concluded it would be to difficult for our ability with manufacturing.

Thanks

In 2015 my team was able to build an H-Drive out of two AM14U bots. All we had then were the basic tools, chopsaw, bandsaw, and a drill press as well as an assortment of hand tools. For our suspension we took a bunch of thin 1/16" washer and can't them around the shank of a 1/2" And stacked them in between where the H-drive met the chassis, like leaf springs in a truck. The hardest part about this drive train is figuring how much you want that center wheel to influence normal driving, if you lower the center wheel to much driving becomes very difficult, if you put it too high you find that you can't strafe. In the end we ended up having to adjust height at each of our competitions because the fields are much more uneven than they seem.

[Zebra_Fact_Man]

My team built a very simple spring adjusted prototype this past offseason.
If I remember, I will post pictures or our system tonight after our build session.

[ImMoMo]

Lovely design, I'm a fan of the clamp on gearboxes.

We too are using them this year, and I was wondering what kind of encoder you are using for this set up?

We ordered the CIMCoder, it seems like a good option, however, I'm worried about clearances with with pinon and driven gear.

Also, have you considered adding a pulley/sprocket reduction... although you would probably have to move a few things around.