What types of metal do you use for your robot in general?

[MAXOFLIFE]

This year we constructed most of our robot using 1"x1" aluminum tubing. It worked, but we had numerous problems: warping from over tightened bolts, extra holes needed to help guide and tighten bolts, etc. I know every year can be different, but what types of metals (and in what shapes and forms) do you mainly use and for what reason? We know the basics: aluminum being lightweight, steel being strong; heavy; and prone to rusting, etc.

Thank you for taking time to help!

[Sperkowsky]

We used a lot of 2x1 and 1x1 Versaframe. We also made use of some aluminum flat stock, steel flat stock, and pieces of old KOP chassis....

We used the Versaframe mostly because of the pre drilled holes and how easy it is to buy. The 1x1 was really just used for extra support and for mounting bumpers. The 2x1 formed the majority of the shooter structure.

The aluminum flat stock was bent and used to build the platform the boulder rests on. We would have probably used steel if we had the means to bend it.

The steel flat stock was used to mount a cylinder.

And, the pieces of old KOP chassis were used as a climber hook, battery mounts, and a little extra support for the underbelly.

[Cam_Team 2619]

Our team uses a lot of .75" x .75" aluminum tubing. Never had a problem with it.

[hrench]

As an engineer in the truck-industry, I've taken Panther Robotics 1108 in a different direction. We use steel.

It costs about half as much, its half-again stronger than aluminum and if it bends, we can just bend it back without losing strength.

We have a flux-core wire-feed welder in the shop, which is inexpensive to operate and the kids learn to make some great looking welds. Add a bracket? don't need to drill and bolt--just weld it on! Also note, we've never had the money for aluminum welding.

Mostly we use 1/2" x 1/2" x 0.062 wall thickness square section tubing, but also on round parts we use EMT conduit. All available at the local farm store or Home Depot in the city. Also cheap at mcmaster.

Takes up less room too. Can't imagine building in 1/2" tubes in aluminum. Would fold like tinkertoys. Steel is super strong.

And oh-yeah--our robot weighs 105 this year. No lightening holes either. Yes, steel is heavier, but we just use less.

I remember aluminum robots put together with rivets--they were always rickety and wobble. These are solid.

[JesseK]

1/16", 1/8", 3/16" and 1/4" 6061 Aluminum plate can be found on our robot. We lay a 4'x4' sheet down on the CNC router bed of whatever thickness we need and cut it from there. One day we'll learn how to CAD metal bends properly, and when we do... look out

Our tubes are 2x1 VersaFrame and 1x1 regular thin wall 6061 Aluminum.

Our standoffs are made from AM Churro or VEX ThunderHex, for the most part. We also have 1" solid aluminum round turned down to make a complex (but sturdy) axle and orthogonal mount for our intake.

Connectors include #10-32 socket head bolts, 3/16" aluminum rivets and 1/4" aluminum rivets. Since ThunderHex and AM Churro are immediately tap-able for 1/4-20, we also use 1/4-20 x 1/2" length into the ends of those.

Originally Posted by hrench

I remember aluminum robots put together with rivets--they were always rickety and wobble. These are solid.

Ooh, ouch. Those are fightin' words.... We're 33 matches into our season with no wobble on our riveted drive train frame. Don't get me wrong - we would have loved to weld it this year, but couldn't find a sponsor who could turn it around in time. So rivets have worked really well. The trick: Cleco clamps, and rivets every half inch. If 2 of the holes were precision-drilled, then we were able to get away with hand punch/drill on the others. VersaFrame helps a lot, IMO.

[MrForbes]

We used very little metal on our robot this year, aside from the aluminum kit chassis. Most everything else is wood. We used a few pieces of aluminum strap, and a couple pieces of thick sheet aluminum for corner gussets. We also used polycarbonate sheet for the top and bottom, mostly to keep things such as the defenses, boulders, and other robots from getting into or snagged on the innards of our robot. And there are a few pieces of steel strap.

[BetaHelix]

Our practice bot was almost entirely made of .075 steel plate, and it was underweight. Our main bot had .090 aluminium side plates and was 5lbs lighter. We also had steel backed bumpers (19.6lbs per pair!)

[Jaci]

We use mostly 3mm aluminium with some similar steel portions where extra reinforcements are needed. For main support structures we usually use 25x25mm SHS, although apart from the drivetrain not much of that was required this year for us.

Most of our parts are bent into shape as sheet metal, however some 90 degree joints (such as our shooting shroud) are riveted (or even welded) into place. Our rhino plates this year are 3mm with supporting churros and SHS to prevent bending and to hold them firmly in place.

Our robot last year was the stock base with a 3mm steel baseplate. Our 'A frame' lifting guiderails were 25x25, 3mm steel SHS, welded into a slanted A frame and bolted to the chassis.

[bigbeezy]

Vast majority is 1x1 and 1x2 Versatubing. We do have some 3/4x3/4x1/16 tube this year.

For plate we mostly use 0.090" 6061, with the occasional 0.040" for light brackets as we can bend it in house. We do have 1/4", 1/2" and even 1" thick AL on the bot this year.

Most hex shafts are AL from VEX, though we do use some steel hex from McMaster. We tried the Thunderhex and I'm not sure if it was just the oversized batch but it was a nightmare to work with and we won't be going back.

We rivet most everything and get critical pieces welded by our local sponsors.

[Chief Hedgehog]

Originally Posted by bigbeezy

Vast majority is 1x1 and 1x2 Versatubing. We do have some 3/4x3/4x1/16 tube this year.

For plate we mostly use 0.090" 6061, with the occasional 0.040" for light brackets as we can bend it in house. We do have 1/4", 1/2" and even 1" thick AL on the bot this year.

Most hex shafts are AL from VEX, though we do use some steel hex from McMaster. We tried the Thunderhex and I'm not sure if it was just the oversized batch but it was a nightmare to work with and we won't be going back.

We rivet most everything and get critical pieces welded by our local sponsors.

I concur on the Thunderhex. What a horrible product - we had one student that spent about 2 days just filing down the Thunderhex so that we could use it. We will be looking at other stuff for next year.

[z_beeblebrox]

Originally Posted by Chief Hedgehog

I concur on the Thunderhex. What a horrible product - we had one student that spent about 2 days just filing down the Thunderhex so that we could use it. We will be looking at other stuff for next year.

We've had success with chucking the ThunderHex in a lathe and sanding it with emery cloth. We can do a 36" piece in a few minutes.

It would be awesome if the tolerances were fixed for next season though...

[pipsqueaker]

Originally Posted by Chief Hedgehog

I concur on the Thunderhex. What a horrible product - we had one student that spent about 2 days just filing down the Thunderhex so that we could use it. We will be looking at other stuff for next year.

It's worth noting that ThunderHex is actually supposed to fit really tight, as theoretically it eliminates the need for collars and can fricton-fit through holes meant for round shaft. We use a ton of it on our robot and we never needed to sand it down to fit.

However, looking at the webpage I do see their notice that their current inventory is oversized due to a manufacturer error, and I do see how working with that could be a bit of a nightmare

[hrench]

I think it's pretty fun that I kicked off a new branch of robot material selection here with my advocacy of steel robots. I was at a regional so I didn't get to participate in the conversation over the weekend, but here's a few words:

Originally Posted by JesseK

Ooh, ouch. Those are fightin' words....

Oh, you know this was meant in the friendliest spirit...1108 has built some rickety riveted robots. I know that airliners are aluminum riveted and they do pretty well, but not with pop-rivets.

Originally Posted by mman1506

Yeh, 1114's robots are always soo rickety and wobbly /s

1114? Are they any good? (Joking, of course they are) Yes, aluminum is a great material.

Originally Posted by ratdude747

Have you ever considered MIG or TIG as an upgrade down the road?

We'd love to have mig or tig, but the welder is my personal welder and a bottle is $150 or so, plus $50 to refill. Mostly we grind the surface of the welds to remove spatter, but with kids welding, grinding the surfaces to make them smoother would probably be helpful anyway.
Probably yes, we'll move up sometime.

Originally Posted by Captain_Kirch

Agree to disagree here. Aluminum is lighter and we use more of it.

Actually, I should mention that I'm an advocate of selecting the material on each component to match the function.

We have steel sides and arms on our robot, but the pneumatic catapult hoop is PVC. The flex actually adds to the strength of the shot.
The Catapult is supported by fiberglass strut-channels on the power-end and aluminum squares with pine inside them to prevent crush on the hold-down end.
We have numerous guards that are polycarbonate
the 'floor' of our frame is 3/8" UHMW so electronic components can be just screwed down with wood screws.
So we've used just about every material on our robot somewhere.

Just like in any engineering, I believe material selection is a process and needs to be thought out for each part. I teach the kids a class on it too.

[Steven Smith]

As many others have said, build using what you have experience working with and tools capable of producing with.

In 2014, my first build season with the team, we had a "basic" shop with drill press, chop saw, small manual mill, etc. Most everything was COTS and we used a lot of VersaFrame product.

Since 2015, we rely on our in house CNC router for large flat parts. In 2015, we used a lot of aluminum tube profiles (1x1-3x2 OD, walls of 0.0625 to 0.125 and everything in between), with custom made flat pieces like gussets, larger panels, etc. Our elevator carriage still used a bit of VersaFrame. Our drivetrain was manually milled tubes for chain in tube.

In 2016, we acquired a manual brake (thanks 2848!) which let us make more complex geometries using our router and more precise sheet metal bends. Our robot is one of the more robust out there, and we are nearly 100% rivet construction. We learned the lesson of moving to 5052 for bending. We also saw a lot of good examples of polycarb usage for mechanisms that bend instead of break, most notably (to us), 1477s intake in 2014, which inspired a lot of polycarb usage on our robot as ball guides, intake mechanisms, shields, etc.

Next year, we plan to use many of the same materials and techniques, and add better jigging to do aluminum tube extrusion bearing holes and lightening patterns on our CNC mill, as well as gearbox designs. The existing gearboxes are all probably better quality than what we can make, but some years the packaging flexibility of making something slightly different would be nice.

Outside of all that, we use a laser cutter to make Delrin spacers in house for cost savings and use 3D printing extensively (ABS/polycarb).

[mwmac]

Team Tators built this year's robot using aluminum with the greatest variation in thicknesses I have ever seen on a robot. All sheet stock is .08" for the chassis while the front plates were milled from 1.5" thick plate, (finished at 1.46") . Yes, they are pocketed....