pic: Sheet Metal Chassis Prototype

[AlecMataloni]

Any particular reasons why you don't want to use rivets? I'm just curious.

[MichaelBick]

Really nice job. I'm also wondering why you decided against rivets, and against dropping the center wheel.

[Chris is me]

Regardless of the reasons, this is an excellent chassis given those constraints. Nice job. How does the gear ratio look?

[sgreco]

Originally Posted by Chris is me

How does the gear ratio look?

I too am wondering the same thing. It looks like a CIMple Box with that direct drives 8" wheels (custom hex output shaft?). If this is in fact the case, this robot likely will not have enough torque to initiate movement of a 150 pound robot (battery and bumpers included), or you will not be able to reach a max speed given the length of the field. Correct me if I'm wrong.

Edit: I realized that the Toughbox mini has a very similar look to the CIMple box, in which case the gearing (depending on which gears you chose) is probably reasonable for a FIRST robot. I'm still curious what the ratio is, and what speeds you expect.

[roystur44]

Increase the flanges on the front and back to add more metal. Consider bending another return flange. Select the aluminum type: 1100, 3003, 6061-T0-T6 or 5052-H32 then check you minimum bend radius with the people who are going to bend your parts.

Needs a integrated belly pan to stiffen the chassis. Add some joggles on the length to make it stiff. Consider a separate electronics panel so you can preassemble your electronics

Don't forget the mounting points for the manipulator.

Needs quick release bumper brackets and battery box

Add clearance through holes to tigthen the CIM on the transmission.

Loctite your nuts before competition.

[Timz3082]

Thanks for the feedback!
the gearbox is a toughbox mini with a 10.7:1 ratio built into the 1/8"" aluminum, this is a bit more reduction than we had last year and it worked great! by great, I mean we though it was the 2nd best drivetrain on the field! (2nd to 141 who had some crazy hyperspace swerve drive which after looking at for about 10 minutes, I still couldn't comprehend! I will now work on the modifications making this a more feasible, and realistic design! For the belly-pan, would there be anything wrong with using 1/2" Birch Plywood? It would be lightened and might end up lighter than aluminum, I will find out!

[Timz3082]

also, how much larger should the flanges on the ends be, currently they are 3/4", wound 1" be acceptable?

[AustinSchuh]

Make the flanges on the front/back of the bot 1.5 - 2" long, and then take the edge and bend a 1/2" flange down from that.

Take another set of the plates that you are using to strengthen the drivetrain tube and put them on the bottom. This will help a lot with strength.

Birch will be fine. You can attach electronics to it quite nicely with some industrial grade double stick tape. The birch will keep your frame square and help prevent the front from bending in when you hit things.

[Aidan S.]

I would suggest using 1/8th inch lexan for the belly pan. It's lighter than wood and more flexible, so it has less of a chance of cracking if you get hit really hard or flip over (I hope that won't happen ). Also, you can easily attach your components with zip ties (or screws, if you like). We went with 1/8th inch lexan last year, and were very satisfied with the results.

[Ninja_Bait]

Originally Posted by Hawkeye610

It's lighter than wood and more flexible, so it has less of a chance of cracking if you get hit really hard or flip over.

I believe the point IS rigidity. Without the rigid base would this still work as well? Was your bot a sheet metal bot?

[Aidan S.]

No, our robot was not sheet metal, but since every almost every FIRST game required some sort of manipulator to be built on top of the drivetrain, those structures would act as a sort of crossbar than reinforced the drivetrain anyways. Since the lexan would save weight, crossbars could be installed on the drivetrain beforehand anyways, and it would still weigh less than with a wooden bellypan.

[Ninja_Bait]

Silly me, we were next to each other in the Galileo pits. I should have remembered.

However, I think that the crossbeams tend to be a nuisance that can actually warp the frame instead of strengthening it, so be careful about that. This'll also depend on the game and the OP's design style. If you plan to design the manipulator beforehand (which you should), you can plan for rigidity from your crossbeams. If you plan to use the infamous rule of fudge and just do it on the spot, you should have a rigid base to build on.

[akoscielski3]

we just built a prototype chassis for offseason (yes it was sheet-metal). And we used lexan in the middle for the electrical board. Lexan is a great way to strengthen the chassis (even though i dont think we needed it). I would recommend rivets, as we just used them for the first time and they seem to be very strong.

Why are you using an omni wheel? Is the center wheel lowered? How thick are the spaces between the lightening holes?

Cool Chassis though