pic: WCD Sheet Metal Hybrid

[rcmolloy]

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[Joe G.]

I like the looks of this! We've done a WCD/Sheet metal hybrid the past two years that leans more towards the sheet metal side of things. It uses nested C-channels to form a box structure in place of the long 1x2s, with belts captured between them. This looks to be a good way to squeeze out some of the generous horizontal space this takes up for teams with more milling capabilities than us.

What function do the small flanged pieces near the sprockets serve?

My gut tells me you want more meat on both the bumper supports and battery mount. I'd be worried about the bumper mounts paralellogramming upwards (or worse, downwards) under load, and the battery mount's overhung corners getting bent by a poorly aimed battery, but the overall chassis structure looks great!

[Ty Tremblay]

Originally Posted by Joe G.

What function do the small flanged pieces near the sprockets serve?

If you're talking about the 4 flanged pieces near the outside wheels, those are bearing blocks that fit in a slot cut into the 2x1. There's a little cam that is used to change the center-to-center distance between the sprockets in order to tension the chain.

[DampRobot]

Other question, what do you have going on for bumper mounts there? What kind of hardware/system will they attach to on the bumper, and are they'd integrated into the bellypan or are they separate parts?

[AustinSchuh]

What thickness aluminum are you picking for you belly pan? I'm assuming that you are picking 5052 for the alloy, since sponsors don't like bending 6061.

I'm kind of worried about your front and back rails crumpling under impact. Our 2013 drive base is pretty smashed in, and that was with at least a 2" flange and a bunch of other reinforcement.

I'm torn on the bumper plate strength. It does look a bit small, but your designs have always had flat plates there, and those seem to hold up. Adding in a bend which is perpendicular to the bumper would help enormously. A different design would be a flat plate on the top of the frame with 2 1/2" bends along the edges which are perpendicular to the frame.

Thanks for sharing!

[JamesCH95]

I really like the elegance of this design. A lot.

My only two comments:

-I think that you should use a 'truss-like' pattern in the bellypan, i.e. triangular cut-outs. I would bet that using triangles instead of quadrilaterals will make the belly-pan stiffer and stronger.

-My personal preference for joining would be riv-nuts instead of rivets. I like the idea of being able to easily remove and service parts. It looks like you could remove and replace a whole drive pod with just a few bolts, which is pretty cool.

[AdamHeard]

Originally Posted by JamesCH95

I really like the elegance of this design. A lot.

My only two comments:

-I think that you should use a 'truss-like' pattern in the bellypan, i.e. triangular cut-outs. I would bet that using triangles instead of quadrilaterals will make the belly-pan stiffer and stronger.

-My personal preference for joining would be riv-nuts instead of rivets. I like the idea of being able to easily remove and service parts. It looks like you could remove and replace a whole drive pod with just a few bolts, which is pretty cool.

I won't comment on the rest of the design, as this is Cory's, not mine, but the bellypan is a fairly similar to what we and others run.

The goal with the diamonds is to create a single web of material from corner to corner. In theory the belly pan could just be the two corner to corner strips without issue. The bellypan really isn't loaded in any other direction (aside from component weight), and additional material doesn't really contribute. It's worth noting our superstructure generally places a crossmember somewhere along the frame which helps the front/rear crossmembers a lot.

Also, we consider the bellypan integral to the frame, so rivets are a much lighter and faster mate.

[Greg Woelki]

Do you think that the frame is really strong enough for using 1/16" wall 2x1? Also, what is your source for that 2x1?

[AdamHeard]

Originally Posted by Greg Woelki

Do you think that the frame is really strong enough for using 1/16" wall 2x1? Also, what is your source for that 2x1?

I don't think Cory specified thickness, I assume he did .125" but do not know.

Both thicknesses we get from Coast Aluminum, who is a full metal supplier. We buy 20' lengths and pay by the pound. IMO this is the best way to buy metal for FRC.

[Greg Woelki]

Originally Posted by AdamHeard

I don't think Cory specified thickness, I assume he did .125" but do not know.

Both thicknesses we get from Coast Aluminum, who is a full metal supplier. We buy 20' lengths and pay by the pound. IMO this is the best way to buy metal for FRC.

Thanks for the supplier. I downloaded the STEP file and it is 0.0625" wall.

[AdamHeard]

Originally Posted by Greg Woelki

Thanks for the supplier. I downloaded the STEP file and it is 0.0625" wall.

Since you're in MA, I doubt they would shop that for (nor would it be logical).

However, I'm certain there is someone filling an equivalent role out there. Figure out where machine shops buy their aluminum and ask them.

[Travis Schuh]

Originally Posted by Greg Woelki

Thanks for the supplier. I downloaded the STEP file and it is 0.0625" wall.

You might check out Admiral Metals. That was the place we would go to for metal while I was out at school near Boston. If I remember correctly, they had a pretty expansive area of ends that they would sell by the pound for a good price.

[JamesCH95]

Originally Posted by AdamHeard

I won't comment on the rest of the design, as this is Cory's, not mine, but the bellypan is a fairly similar to what we and others run.

The goal with the diamonds is to create a single web of material from corner to corner. In theory the belly pan could just be the two corner to corner strips without issue. The bellypan really isn't loaded in any other direction (aside from component weight), and additional material doesn't really contribute. It's worth noting our superstructure generally places a crossmember somewhere along the frame which helps the front/rear crossmembers a lot.

Also, we consider the bellypan integral to the frame, so rivets are a much lighter and faster mate.

If the extra strength isn't needed then please ignore my suggestion If the frame rails need more support to resist bending, then it may be worth considering.

No doubt rivets are lighter and work well. Rivnuts are simply my general preference.

[Michael Corsetto]

Originally Posted by AustinSchuh

I'm torn on the bumper plate strength. It does look a bit small, but your designs have always had flat plates there, and those seem to hold up. Adding in a bend which is perpendicular to the bumper would help enormously. A different design would be a flat plate on the top of the frame with 2 1/2" bends along the edges which are perpendicular to the frame.

Initially, we had thin flat plates for bumper supports to bridge the WCD gap. After our second event, we iterated to a bended support. We had a bend perpendicular to the bumper that went between top and bottom plates, so the bumper support was riveted on the top and bottom of the WCD rail. This worked out very well for us, lasting through many Aerial Assault matches. Would definitely recommend using a similar approach in place of your current solution.

Overall, very cool/creative idea, I like it.

-Mike

[Joe G.]

Originally Posted by Ty Tremblay

If you're talking about the 4 flanged pieces near the outside wheels, those are bearing blocks that fit in a slot cut into the 2x1. There's a little cam that is used to change the center-to-center distance between the sprockets in order to tension the chain.

I meant the angle pieces highlighted in blue below, not the 973-style WCD bearing blocks.