pic: FRC1293 Prototype 6wd Chassis



A quick inventor assembly of one of the multiple chassis we’ll be testing this offseason. The assembly is missing the sprockets and axle spacers but that is just do to time and lazyness. Took a team member and I about 3.5 hours to create this, and we hope to have it jetted out this sunday. The old electronics are slapped on since we do plan on testing this very soon. Spacer dowels are delrin, sideplates aluminum (wood for the prototype) and it has 2 1.5in 8020 bars holding the sideplates to each other. The transmissions are just AM Toughboxes with the extended shaft (increases output shaft by 3.5").

Also the view looks kind of “different” because i’m using the “true 3d” view mode in inventor, I feel it gives it a better look for screenshots (but is a total pain to work in, i’d reccommend against using it for any work hehe)

Nice cad job, are you guys going with kop wheels??? It is just me or is the battery supported by air? What are the real sideplates made out of (aluminum grade)? Too many questions, so little time. That is a pretty nice drawing taking into account time spent on it.:slight_smile:

Real sideplates will probably be 1/8" 6061 alu backed with 3/8" UHMW, the prototype will just be 1/2" plywood.

The battery is supported by air in the assembly because I forgot to put in the battery holder into the assembly. It is just an aluminum sheet with 4 bent tabs that are attached to the inside faces of the 8020 bridging the space between them under the electronics board. The tabs are to lower the aluminum sheet so the battery sits lower.

6" AM KOP wheels for now

Thanks for the compliment :smiley:

If you guys have the tools to do it, I would recommend that you fold the top of the side plate over to make it a lot stiffer and stronger.

We made a drive train last year that was 2 plates of 1/8" aluminum side plates on either side of our wheels with spacers to hold the plates together. We folded the top and bottom of each plate over to make a 1/2 inch or so tab. It held up very well.

First off, I’d like to say this looks like a great design, very weight friendly.

1902 has done it two different ways the last two years. In 07 it was flat 1/8" plate with a ton of rivets and spacers.
http://www.chiefdelphi.com/media/photos/26796

Last year it was lots of rivets, spacers, and we flanged the top and bottom of the plates. We did this because in 07 the frame seemed to warp a bit with impacts and what not. It never was a problem because the bumpers are strong enough to support quite an impact, so the bumpers ended up keeping the drive plates relatively sturdy.

http://picasaweb.google.com/DanRRichardson/2008Robot#5165200838081699890

However bending the plates, when femed showed an individual panel was much stronger. ( If I remember correctly it was “14x” stronger but the flat plate failed under the loading so take that for what you will. ) For 1902 the verdict was, 1/8" is ok…, but 1/8" with 2 .5" bends are SOO much better. Its not too hard to find a sheet metal break, or a metal fab shop to do this for you, for free, or really cheap. I suggest if your going with 1/8", trying to throw some bends on that bot.

All parts of a ROBOT between 0 and i belive it was 8.5 inches from the
ground that are used to push against or interact with an
opposing ROBOT must be within 10 degrees of vertical.

This was the rule in previous years it may change. This is just a friendly warning so that you do not have to change anything at an event. The design looks clean and open for easy access to the various systems. Do you have any wieght values yet?

I don’t think those chamfered parts would ever interact with another robot, and by my entirely unofficial interpretation of a previous year’s rule, would be ok.

Don’t forget a way to attach bumpers (assuming they’ll be mandatory in '09)

However, all of the angled bits hanging down past the bottom flat part are unnecessary material. It is not gaining the design any strength and the extra weight could be avoided by eliminating it all together. Possibly make the entire bottom of the frame flat with a 1/2" flange for extra strength.

It could, but probably only the top. I was planning on creating a small 5" bumper plate that covers the front of the sideplates. It would attach using the same holes as the spacers.

It would have the added benefit of making us legal, AND keeping stuff out of the wheels ;-). the bot shouldn’t weigh more than 50 or so pounds with the electronics (not including battery), but i’ll work in inventor for a bit and come up with an accurate calculation of its total weight sooner or later.

Also i’ll look into a shop that can do some flanges for us so I don’t have to use any UHMW to back and reinforce the aluminum. Thanks for the tips so far.

:edit: The extra bit around the wheels are mostly a safety precaution to just keep stuff from jabbing into the KOP wheels, they arn’t the sturdiest wheels around.

The bottom chamfer is fine (Team 1319 has done that in the past) however the top chamfer does create a wedge like surface (which is why we haven’t). While I totally agree with you that the top chamfer would not ever come in contact with other robots I was just pointing out what I have seen teams have to fix at a regional in the past. I suppose they would have much rather have had you as an inspector.:smiley:

Thats true but imo the added weight is not worth the small small chance that something gets in the spokes and kills the wheel. If something were to happen, it would be a quick swap anyways.

with the way the toughboxes are mounted, I cannot make the center part of the chassis smaller than 5" tall, so I’m going to keep the inside chamfers.

However I’ll think about flattening the front and rear and cutting some material off.

Thanks again for the tips.

It doesn’t have to be that tall on both sides though.

I like the cad drawing. Lol where is the wiring. Just joking. I like the prototype though.

Nice design–looks like it can be assembled very quickly.

Why did you choose to use 1/2"-thick sideplates? Have you used this in the past and found that you need to go that thick? With the use of the spacers along with the heavy-duty 80/20 cross-beams, it seems like you could make them much thinner, especially if they’re being protected by bumpers.

Also, are the wheel modules/side plates made to be universal, meaning that you could use the same pieces on either the left or right sides?

Yes, the sideplates are universal, the assemblies are just mirrored from each other.

As an update we changed the look but it is still the same basic design. We are now using 1/8" thick 6061 alu sheet with flanges on the top and bottom of the sideplate to prevent warping. 4" long, 5/8" diameter UHMW dowels for the spacers with 4 1/2" long 1/4"-20 bolts to go through the dowels and hold the sideplates together. We made some changes to the 8020 and repositioned them pretty drastically for more room for the manipulator, and we have also changed our wheel locations slightly to allow easier turning for this year.