pic: 2851 2014 off-season design: Bottom view with electronics

[wyrzykowskij1]

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[449_PeterPeng]

Personally, I like the idea of accessable electronics boards. This year, we had a lot of maintainance problems when we put the electronics board on the bellypan and below all the mechanisms.

Though, I don't see how practical it would be to have the board open downward, since maintainance would involve flipping robot to its sides. Have you considered making the board fold upwards?

[Kevin Leonard]

Just make sure that doesn't open mid-match!

[Anthony Galea]

Originally Posted by Kevin Leonard

Just make sure that doesn't open mid-match!

That could be simple, using small bolts or quick release bumper pins.

[wyrzykowskij1]

Originally Posted by 449_PeterPeng

Personally, I like the idea of accessable electronics boards. This year, we had a lot of maintainance problems when we put the electronics board on the bellypan and below all the mechanisms.

Though, I don't see how practical it would be to have the board open downward, since maintainance would involve flipping robot to its sides. Have you considered making the board fold upwards?

Yeah, I have considered that. However, I don't think I could maintain the modularity that the shooter has if I had them open upward. (it's only a couple bolts to remove it). Also, flipping the robot on its side isn't too bad if you're on an open workbench. Since this will never see competition, flipping it shouldn't be too hard. I think that's definitely something to consider for a competition robot though, as I plan on using the general idea in future competition designs. Having easily accessible electronics can definitely be helpful.

Also, it already uses quick release pins to open the doors. (3 on the side where the cRIO, sidecar, and PDB are, and 1 for each door where the jags and spikes are) Those would probably be tied in with cables. (it would be catastrophic if they opened in a match! Yikes!)

[cfair]

I think it's a fabulous idea. We are doing a new chassis this year with a similar arrangement. Every other year it seems we end up with a superstructure that blocks access to the electronics; may as well plan for it. If the electronics turns out to be accessible from above, all the better. We plan on using rivet nuts with locktite to hold it in place.

[wyrzykowskij1]

Originally Posted by cfair

I think it's a fabulous idea. We are doing a new chassis this year with a similar arrangement. Every other year it seems we end up with a superstructure that blocks access to the electronics; may as well plan for it. If the electronics turns out to be accessible from above, all the better. We plan on using rivet nuts with locktite to hold it in place.

That sounds cool. Are you using the flipping up or down arrangement, and what is different? The only problem I've seen with this arrangement is that the torsional integrity of the chassis is slightly sacrificed by not being able to use a full bellypan on the bottom.

[cfair]

I'll see if our guys can post a CAD. We have two center cross members about where yours are, with the piano hinges attached there by rivets. Our electronics hinges down from the center cross members, accessible from the bottom, with the rivet nuts on the extreme ends of the chassis to hold the hinges closed. We will have a shear plate welded between the two center cross members, and we'll mount our compressor on that. We are also putting small gussets at the corners of the chassis for shear (I think that's more of a concern than torsional rigidity with regards to a belly pan). Also the battery will go in a "cage" and that cage will be mounted in a location tbd depending on access and the mechanisms above the electronics. Our chassis is welded tubular 1x2 for the most part. It's our first time with a west-coast style drive...

[wyrzykowskij1]

Originally Posted by cfair

I'll see if our guys can post a CAD. We have two center cross members about where yours are, with the piano hinges attached there by rivets. Our electronics hinges down from the center cross members, accessible from the bottom, with the rivet nuts on the extreme ends of the chassis to hold the hinges closed. We will have a shear plate welded between the two center cross members, and we'll mount our compressor on that. We are also putting small gussets at the corners of the chassis for shear (I think that's more of a concern than torsional rigidity with regards to a belly pan). Also the battery will go in a "cage" and that cage will be mounted in a location tbd depending on access and the mechanisms above the electronics. Our chassis is welded tubular 1x2 for the most part. It's our first time with a west-coast style drive...

What advantages does a tubular chassis have? Also, this would be our first west coast drive too, so I made sure that there was a lot of support to prevent the side modules from twisting upwards from the weight of the frame. It's probably overkill, but it has to be strong anyway.

[cfair]

It looks like you have a sheet metal frame. We do not have sheet metal sponsors, so we've never ventured into that scary place. My first concern for you would be parallelogramming (shear) for the chassis when you get a violent hit on the corner. The welded tubular frame does pretty well against those corner hits, but it still definitely needs a shear plate. Other teams would speak with more authority on how to achieve the same thing with sheet metal, but I would start with lots of rivets on your shear plate or gussets. I see you have basically created box cross sections for the sides and end members. That's great; you just need to figure out how to connect them and resist shear.

As for the advantages: the biggest advantage of tubular is simplicity. From my point of view, the easiest chassis is an off-the-shelf chassis, the next easiest is one the sorta off the shelf (like ours: we're using versablocks), the next is a custom one using plates or tubes (what we usually do), and the most difficult is sheet metal. Just so you know, we routinely find 1/8" wall 1" square tubing bending dramatically because of hits to our front and rear bumpers .

[wyrzykowskij1]

Originally Posted by cfair

It looks like you have a sheet metal frame. We do not have sheet metal sponsors, so we've never ventured into that scary place. My first concern for you would be parallelogramming (shear) for the chassis when you get a violent hit on the corner. The welded tubular frame does pretty well against those corner hits, but it still definitely needs a shear plate. Other teams would speak with more authority on how to achieve the same thing with sheet metal, but I would start with lots of rivets on your shear plate or gussets. I see you have basically created box cross sections for the sides and end members. That's great; you just need to figure out how to connect them and resist shear.

As for the advantages: the biggest advantage of tubular is simplicity. From my point of view, the easiest chassis is an off-the-shelf chassis, the next easiest is one the sorta off the shelf (like ours: we're using versablocks), the next is a custom one using plates or tubes (what we usually do), and the most difficult is sheet metal. Just so you know, we routinely find 1/8" wall 1" square tubing bending dramatically because of hits to our front and rear bumpers .

As shown here: http://www.chiefdelphi.com/media/photos/41002?
I do have a piece in the center on the bottom of the chassis to prevent shear, and the shooter bolted on top should help some. You don't think that would be enough? Also, the reason I did sheet metal was because I wanted to be able to do this with minimal hand fabrication at our build site. Another goal was for it to be easy to build, and as soon as we get the parts back from Accu-Rite, we can basically just assemble it.

[cfair]

That's a nice looking chassis. I don't have the experience with sheet metal to say whether it's enough or not, but i like your T-shaped bottom plate, and if that's a piece of lexan on top, it could help a lot too. Box structures are good, and box structures made out of box structures are really good. Nice chassis! Can't see what you're doing for gearboxes...

[Twins Inc.]

Originally Posted by cfair

I'll see if our guys can post a CAD. We have two center cross members about where yours are, with the piano hinges attached there by rivets. Our electronics hinges down from the center cross members, accessible from the bottom, with the rivet nuts on the extreme ends of the chassis to hold the hinges closed. We will have a shear plate welded between the two center cross members, and we'll mount our compressor on that. We are also putting small gussets at the corners of the chassis for shear (I think that's more of a concern than torsional rigidity with regards to a belly pan). Also the battery will go in a "cage" and that cage will be mounted in a location tbd depending on access and the mechanisms above the electronics. Our chassis is welded tubular 1x2 for the most part. It's our first time with a west-coast style drive...

Originally Posted by cfair

As for the advantages: the biggest advantage of tubular is simplicity. From my point of view, the easiest chassis is an off-the-shelf chassis, the next easiest is one the sorta off the shelf (like ours: we're using versablocks), the next is a custom one using plates or tubes (what we usually do), and the most difficult is sheet metal. Just so you know, we routinely find 1/8" wall 1" square tubing bending dramatically because of hits to our front and rear bumpers.

If you guys could post some CAD that would be great. I absolutely agree with your ranking of easy-hard. We have used 1x2 tubing, 1/16 wall for the past two years with mechanic with great success. It was easy to put together, we used gussets and self-tapping screws to assemble it all in about two hours. However the self tapping-screws really loosened up after so much contact and hitting last season, and welding seems like a better option as far as durability goes. We are also looking into a 8 wheels drive for the first time, while we know how to make a stellar mechanum drive, we are delving for the first time with a "west coast" style.

[wyrzykowskij1]

Originally Posted by cfair

That's a nice looking chassis. I don't have the experience with sheet metal to say whether it's enough or not, but i like your T-shaped bottom plate, and if that's a piece of lexan on top, it could help a lot too. Box structures are good, and box structures made out of box structures are really good. Nice chassis! Can't see what you're doing for gearboxes...

Thanks! We would be using VEXpro single stage double reduction gearboxes geared at something like 21 ft/s because it's what we already have, and we also want this robot to be relatively cheap.

[Pravin N]

Here is a simple CAD of our West Coast Chassis with the drop down e-plates cfair was talking about. We have two e-plates on this robot, and both are able to be dropped. However, in this CAD I only dropped down one to show what one e-plate would look like when it is not dropped.

wyrzykowskij1 also asked what the dimensions of this robot are. Currently we are at 29.5 inches x 26.25 inches.