pic: 25lb Drivetrain

[Deke]

Originally Posted by Cothron Theiss

Just because I'm curious and I've never worked with belly pans before, what advantages/disadvantages do they offer? I've heard that they add a whole lot of torsional stiffness to a chassis in a more weight-efficient way than a cross bar, but other than that I'm not sure.

Think of the belly pan like a bunch of strings or cables attached and tied everywhere at the base. It provides additional stiffness when the frame moves away from the belly pan and creates tension, but is very weak when in compression. Since it is attached all the way around, some part will always be in tension, providing more stiffness in the frame.

It is just one way of many ways to add stiffness to the frame. A disadvantage is that it is time consuming to make if you plan out all your electronics and place the holes for tapping and bolting then down. Also, depending on the rest of the frame members may not be necessary. In a case like this, where the frame members are light, the belly pan can give the stiffness needed to perform like a heavier drive train.

[notmattlythgoe]

Originally Posted by Deke

Think of the belly pan like a bunch of strings or cables attached and tied everywhere at the base. It provides additional stiffness when the frame moves away from the belly pan and creates tension, but is very weak when in compression. Since it is attached all the way around, some part will always be in tension, providing more stiffness in the frame.

It is just one way of many ways to add stiffness to the frame. A disadvantage is that it is time consuming to make if you plan out all your electronics and place the holes for tapping and bolting then down. Also, depending on the rest of the frame members may not be necessary. In a case like this, where the frame members are light, the belly pan can give the stiffness needed to perform like a heavier drive train.

Using something like this allows you to create a bellypan very quickly and allows for flexibility in regards to electronics layouts.

[Chris is me]

Originally Posted by notmattlythgoe

Using something like this allows you to create a bellypan very quickly and allows for flexibility in regards to electronics layouts.

In terms of easily laying out electronics, a perforated polycarbonate belly pan is an excellent choice. In terms of structural rigidity, a large thin sheet of polycarbonate is not ideal. Something like Baltic birch plywood would be a better choice for a combination of rigid, lightweight, and flexible for mounting electronics.

[Cothron Theiss]

Thanks to everyone for the info! I don't think my team really has the resources to make a bellypan, but it's always good to learn.

[Knufire]

Originally Posted by Cothron Theiss

Thanks to everyone for the info! I don't think my team really has the resources to make a bellypan, but it's always good to learn.

5188 used baltic birch plywood last season. It really doesn't get much easier than that. Just cut a square the size of your frame and rivet to the bottom. We got a 4'x8' sheet from the local Menards.

[Cothron Theiss]

Originally Posted by Knufire

5188 used baltic birch plywood last season. It really doesn't get much easier than that. Just cut a square the size of your frame and rivet to the bottom. We got a 4'x8' sheet from the local Menards.

Oh, you don't use a lightening pattern if you go with a plywood option? Nevermind, we could do that. (Now that I think about it, that should have been obvious.)

Though, my team has very strong aluminum welding capabilities, so we will probably stick with what has worked for us so far. Also, our robots have weighed in at about 100 pounds the past two years, so we should probably work more on increasing our scoring capability than trying to fix problems we've never had.

[ASD20]

Originally Posted by Cothron Theiss

Oh, you don't use a lightening pattern if you go with a plywood option? Nevermind, we could do that. (Now that I think about it, that should have been obvious.)

You could do a little, though it probably won't save you much weight at all.

[Knufire]

Originally Posted by Cothron Theiss

Oh, you don't use a lightening pattern if you go with a plywood option?

Nope.

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