pic: 2011 Drive Prototype

Made this a few months ago, and i finally got my sw running again, so here it is.
The shifters are very close to 1 lb(about 1.01) with all screws and pneumatics mount.
The chain is cam tensioned, but we are trying to keep the way that the cams work a secret. So they arent in this drawing.

Questions, Concerns, and Comments are welcome.

A few questions:

  1. Are the cam tensioners any different than the standard 254/968 style? Based on their mount location it doesn’t look any different, in which case there’s not much point to keeping them “a secret”.

  2. Did you remember to set material properties on the compressor and CIMs? Right now you have 11 pounds in CIMs and 4.3 pounds in the compressor, which means everything else shown weighs only ~18 pounds?

  3. What are your transmissions made of that you get them down to 1 pound? I’m curious. I’ve basically found through CAD that the only way to get a shifter in a similar application down to 1.01 pound would be to switch to suboptimal (as I’ve been told) parts, or like 1/8th delrin or something ridiculous like that. How’d you get this transmission to 1 pound?

If everything’s as it seems and you made a 34 pound chassis that does all that, good job!

That’s some smexy stuff.

Just a quick question about how the bearing blocks are mounted? I’m not exactly sure how that works.

  • Sunny

It looks like the frame may be a bit unstable in the short direction. Would it be possible to add some angled supports like you have in the long direction to strengthen the frame?

That frame should be perfectly rigid and structurally sound. Its fine as is.


Why are no angle supports needed for the short direction?

There’s a belly pan spanning the width of the robot. Generally such pans are used as structural members of the chassis (see 233/254’s frames)

Maybe I didn’t word the question clearly. I was referencing the upper frame’s supports, not the lower portion of the chassis.

If there are going to be any large sideways forces acting on the upper frame in the lateral direction (like a “reverse curl” lifter) then some triangulation of the frame in that direction might be warranted.

Looks like a nice design. A prototype is a functioning physical mockup or first run mechanism. For reference:

Prototype -noun The original or model on which something is based or formed.

Design -noun An outline, sketch, or plan, as of the form and structure of a work of art, an edifice, or a machine to be executed or constructed.

I quite like your modeling work, keep practicing! My suggestions for the design:
-You probably don’t need the superstructure.
-Have you taken into account materials? Depending on what thicknesses and alloys you’re planning on using, you might be able to save some weight here and there.
-How thick is your belly pan? It seems rather thick. You should be able to go pretty thin, ie .090 or .040 while still maintaining plenty of strength if you’re securing it in place correctly.
-“Secret CAM system”, huh? Now I’m curious! :stuck_out_tongue:

Yes, you did not word it correctly. But, since superstructures are game-based anyway, you usually don’t see many teams using pre-designed superstructures, as is. However, it is a good idea to always keep mounting methods in mind, such as the hole patterns in kit frame rails and 973’s frame rails.


Great design work, Marcus. You definitely have some nice skills.

Well the cams method of turning are different, not the actual block.

Yes all the materials are set. The reason that it is so light is because the upper-structure is made of 1/16in aluminum

They are made of 1/4in Delrin and 7075 Aluminum

They slide inside of of a square cutout, while a cam (involute of a circle) with lots of tiny ridges sort of ratchets into place. the ridges fit onto the radius of the bearing block. PM Cory if you want to get the total lowdown.

Thanks for the the info! Well the upper-structure is 1/16in. The belly pan could be lighter, but right now it only weighs about 2lbs so if less weight is needed i will change it.

The secret CAM system does not necessarily lie in the blocks or the actual cam, it lies within the method in which the CAMS are turned… Think about it

How are you putting the frame together? Bolts and brackets? Welding? The concept is good (though you should have some additional triangulation as some have mentioned). You just need a little more detailing for it to be 100%.

Thanks Akash

Be wary, welding 1/8" wall to 1/16" wall can be entertaining. Are you planning on having a welder do it for you, or will a student be doing the welding? 1/16" wall is veeeeery thin, and can splatter and deform under the hands of a less experienced welder.

Also if anyone hasn’t noticed, there are two different heat sinks on the CIMS. Does anyone have any comments and/or preferences.

I doubt you’ll need much heat work on the CIM’s unless you’re REALLY overworking them. We never had any heat issues on any of our robots.

I would agree with your warning. My team bolted our chassis last year, but in 2009 we had a fairly complex chassis of a mix between 1/16 and 1/8, wall tubing. If a professional welder is doing it you have nothing to worry about, but if he’s not you have a lot to worry about. I tend to be an aluminum type of guy, but if you don’t have an experienced welder, then you could go with steel, and shrink the wall sizes significantly. My team has a mentor who, among othert things, is a very good welder, and we had no problems with our frame, but we have let kids weld on prototypes and such that weren’t on the real robot, and it didn’t turn out so well.

I like where the model is headed, keep up the good work.