pic: WCD off season chassis from 2471

[pribusin]

Got it - thanks.

Are those 3" x 0.875" wheels? How are they kept from slipping off the hex shaft?

[Nate Laverdure]

Originally Posted by RobotsThatWork

Two 16 tooth vexpro sprockets do not sit next to each other inside the 2x1x1/8 (so width). This is true for both when bearings are press-fitted, and when I use a versa bearing block. The Sprocket with Chain attached to it has a total diameter of 0.491 inches. When I put 2 back to back it would be too wide to fit inside the boxtubing. Any solutions?

We chose to avoid this problem by using 2 x 1.5 x 1/8 tube.

The 17t sprocket works in the 2 x 1 x 1/8 because it has a large enough pitch diameter that the chain clears the 1.125 bearing OD.

[jman4747]

Originally Posted by pribusin

Got it - thanks.

Are those 3" x 0.875" wheels? How are they kept from slipping off the hex shaft?

External retaining rings: http://www.mcmaster.com/#97633a200/=102dny4

[Nebster]

What are you using to hold the corners of the frame together? It's not clear to me

[notmattlythgoe]

Originally Posted by Nebster

What are you using to hold the corners of the frame together? It's not clear to me

There are blocks in the ladders with through bolts going through the rails.

[Ty Tremblay]

Originally Posted by Nebster

What are you using to hold the corners of the frame together? It's not clear to me

http://www.team221.com/order.php?cat=15

See "Chassis Tube Connector"

[Bryce2471]

Originally Posted by Nebster

What are you using to hold the corners of the frame together? It's not clear to me

This was a point of much discussion while in the design phase. We thought gussets would be stronger, but using blocks would fit with the chain in tube solution better.

Originally Posted by notmattlythgoe

There are blocks in the ladders with through bolts going through the rails.

This is what we ended up going with, partly because the belly pan is adding a lot of corner to corner strength already.

Originally Posted by Ty Tremblay

http://www.team221.com/order.php?cat=15

See "Chassis Tube Connector"

We did not use these, but they look to be functionally equivalent. The plastic blocks ended up being a good project for younger students to get some training and experience in.

[cxcad]

It would be interesting to see the FEA for the block vs gusset design. On my team the thought was that blocks were stronger because the blocks were pulling the frame members toward each other.

[zinthorne]

Does anyone know where to find a cad file for this?
The half inch hex

[asid61]

Originally Posted by zinthorne

Does anyone know where to find a cad file for this?
The half inch hex

Because I couldn't find it, I just downloaded the round version, put a hex bore in it, re-saved it as a STEP file, and reopened it. That gave me the 1/2" hex 17t double sprocket.

[zinthorne]

Originally Posted by asid61

Because I couldn't find it, I just downloaded the round version, put a hex bore in it, re-saved it as a STEP file, and reopened it. That gave me the 1/2" hex 17t double sprocket.

I can not find the round version. Am I missing something on the website?

[Greg Woelki]

Originally Posted by zinthorne

I can not find the round version. Am I missing something on the website?

I emailed them about it last year. The file can be found here.

[Jacob Bendicksen]

Wait, Mean Machine's not doing swerve?

Glad to see you're having fun and building robustly for BunnyBots -- should be a fun event.

[Nebster]

What are you doing for center drop? Do the sprockets you're using inside the tube have enough clearance with the walls of the tubing for a center drop? I haven't seen that done before but since you're using 1/16" tubing it could be possible.

Do you feel 1/16" walled tubing is strong enough for a traditional drive train?

[Bryce2471]

Originally Posted by Jacob Bendicksen

Wait, Mean Machine's not doing swerve?

Glad to see you're having fun and building robustly for BunnyBots -- should be a fun event.

Yep, I'm looking forward to it!

Originally Posted by Nebster

What are you doing for center drop? Do the sprockets you're using inside the tube have enough clearance with the walls of the tubing for a center drop? I haven't seen that done before but since you're using 1/16" tubing it could be possible.

The bearing blocks we are using have their bearing holes drilled 1/16" off center. The center wheel has its block upside down compared to the outer wheels, so that gives us 0.125" drop. If it tips around too much or is too squirrely, we will flip one of the outside wheels for effectivly a 0.0625" drop. We are using 16t #25 chain sprockets.

Do you feel 1/16" walled tubing is strong enough for a traditional drive train?

I think so, but we'll know for sure by the end of the month.
Anything that survives this BunnBot game will certainly be "strong enough for a traditional drive train"