View Full Version : What types of metal do you use for your robot in general?
MAXOFLIFE
22-03-2016, 07:09
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
22-03-2016, 07:19
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
22-03-2016, 07:34
Our team uses a lot of .75" x .75" aluminum tubing. Never had a problem with it.
Richard Wallace
22-03-2016, 07:56
... warping from over tightened bolts, ...
If your team has access to a wood shop (table saw, planer, joiner, etc.) it is easy to make tight fitting wooden plugs, one to three inches long, to go inside rectangular or square aluminum tubes. This makes it easier to join tubes, using gussets, through-bolts, pivot bushings, etc., without crushing them when you tighten the fasteners.
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.
Nirnaeth
22-03-2016, 08:00
We use 1x1 T-slotted extrusion. Never had a problem.
InFlight
22-03-2016, 08:10
There's different levels of frames depending on experience, machining capabilities, and CAD use.
Kit Frames.
Hand Built with Alluminum Cross Sections
Machined Alluminum Cross Sections
Machined and Welded Alluminum Cross Sections
Sheet Metal Waterjeted (Or CNC Milled) and bent/riveted
We use various materials based on its application.
2 x 1 Aluminum tubing:
Drivetrain
Some structural components, especially those that need a bearing hole
1 x 1 Aluminum tubing:
Assemblies that need to be strong but are not structural in nature
Thin wall versa-frame for low load applications
Aluminum Sheet (1/8" and 1/4"):
Gussets
Mounting brackets
Other applications where a box tube is overkill
Lexan:
Usually for aesthetic uses
Can be pretty useful if you are creative with it (bend with heat gun for various shapes)
In addition to KoP Chassis parts, we used Vex versaframe, 2x1x1/8" aluminum channel, and 1-1/4"x1-1/4"x1/8" channel this year.
You are less likely to crush tubes if you use blind rivets rather than bolts. You will need about twice as many, but they're much lighter than bolts and don't crush tubes.
The only place we usually use steel is where we do use bolts and nuts, a few shafts. chain, and internals of COTS items.
We made a few parts out of a rubbermaid garbage can this year. Not for structure, but it worked well keeping the cheval de frise out of our robot, and if we'd had a lot of trouble running over boulders, we had figured out a flap on the front made of rubbermaid to push boulders away but allowing us to use the wedge for climbing over obstacles.
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 :D
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.
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 (http://www.thebluealliance.com/team/1885) 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
22-03-2016, 09:15
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
22-03-2016, 09:29
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!)
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
22-03-2016, 09:44
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.
BeardyMentor
22-03-2016, 19:04
lets see, this year involved:
1/4x 4" flat bar for the intake pivot and motor mount. (6061)
1/16" 1x1" tubing to support and making up the intake frame (6061)
Piano hinge for anything operable in the robot that was not powered by a motor. (in this case it was to allow us easy access to electronics on the bottom of the robot.
3x3 aluminum angle stock (6061) for PG motor mounts
KOP chassis and bumper mounting kit. (50 series aluminum I believe)
where ever possible tubes were connected with gussets and rivets or rivnuts. This makes it much harder to crush the tubing.
and a metric but load of polycarbonate in 1/8" and 1/4" thicknesses. This makes up almost all gussets and the belly pan of the robot that was cut then thermoformed to fit the chassis so it wraps up the front and back in one continuous piece.
and some trace amounts of aluminum bar stock in rectangular and round flavors for spacers and mounting bosses for the tubing where it needed to T into a flat plate.
z_beeblebrox
22-03-2016, 19:20
1/4" baltic birch plywood is most of our metal, whether for structures or gussets. It's exceptionally strong, lightweight, easy-to-machine (even without a laser cutter) and inexpensive. We also use some 1/8" plywood for small or non-structural stuff.
In terms of actual metal, we mostly use 1x1x1/16" square 6061 tube. Its profile gives good resistance to bending and twisting and its thin wall keeps weight low. Also, lots of Vex 1/2" tube axle (with the ends tapped for 5/16-18 bolts) for both axles and standoffs.
We also have some small parts that take high loads (axle mounts, winch ratchet and pulleys) laser cut from .125" 5052 aluminum by a sheet metal shop that sponsors us.
We'll also make small parts out of HDPE or Delrin on our CNC router or from thin delrin sheet on our laser cutter. Lexan sheets are also occasionally used.
We occasionally use 1x1x1/8" or 2x2x1/8" 6061 angle and 1/8" or 1/16" 5052 sheet if it better suits the application.
For fasteners we use #8 Torx screws for wood-wood joints, 3/16" rivets where possible in metal (lighter, easier to work with than bolts), 10-32 and 1/4-20 bolts where rivets won't fit or aren't strong enough and 5/16-18 bolts for attaching tube axle. Mostly socket-head cap screws from McMaster-Carr with nylock nuts.
Edit: glad to see a good mechanical design discussion thread going. I've been missing these.
Metal? What's that?
http://www.riotcrew.org/robotpix/12374236445_11b5e13efe_z.jpg
http://www.riotcrew.org/robotpix/12310965965_b8ba58c546_z.jpg
http://www.riotcrew.org/robotpix/13015705794_d656e4606f_z.jpg
http://www.riotcrew.org/robotpix/16785672425_d806149a0e_z.jpg
dmorewood
22-03-2016, 19:56
In your original post you have the basic flat sheet aluminum. But if you go down that road you also need to understand the different types and how to use it. First off you need to have a dedicated CAD designer that understands how to design with sheet metal and the appropriate way to bend and rivet Aluminum. Also the two most common types of aluminum for FRC, and what I recommend for your first year designing with it, is 5052 and 6061.
5052 should be used in flanged(bent) pieces. Technically you can use it for just flat pieces to, but it's not as strong as 6061.
6061 should never be used in a bent piece. The metal has a interesting habit of cracking and "exploding" when bent in a break.
Oh and by the way you will also need to find a company that can cut and bend your aluminum design for you. Depending where your team is located I may be able to help you with that.
Max Boord
22-03-2016, 20:01
1065 uses .125 thick C and L channel as well as versa tubing for our robot construction. We buy large amounts of it before the season starts and get it powder coated early in the build season so the end robot is always powder coated without taking time out of the build season to get it done.
4592 is an all sheet metal team. So the entire robot is built from .090 5052 made by our sheet metal sponsors. Occasionally .125 inch is used when thinner material is not strong enough. We also use quarter inch thick plate for gearboxes and wheel hubs.
mman1506
22-03-2016, 20:58
I remember aluminum robots put together with rivets--they were always rickety and wobble. These are solid.
Yeh, 1114's robots are always soo rickety and wobbly /s
Chief Hedgehog
22-03-2016, 21:13
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
22-03-2016, 21:20
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...
ratdude747
22-03-2016, 21:25
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.
Have you ever considered MIG or TIG as an upgrade down the road? Flux core welding has at least in my experience been a bit sloppier due to the slag. MIG is just as easy and produces better welds when welding indoors. TIG, while often considered an "aluminum" process, is also great for steel and allows for cheaper TIG equipment (AC is required for aluminum and adds quite a bit of cost). Sure, the gases add cost, but the resulting welds are better looking (no slag to chip) and possibly stronger (although that's more a factor of the welder's skill).
Yeh, 1114's robots are always soo rickety and wobbly /s
Forget 1114, look at 148! :P
All of that aside, we use:
2x1 aluminum tube, 1/8" and 1/16" wall. We use the 1/8" wherever there are bearings in the tube, and 1/16" when we don't need the strength or aren't worried about crushing.
1x1 aluminum tube, 1/8" and 1/16" wall. 1/8" wall is more common for the strength. 1/16" wall is rather rare but comes in handy for small stuff (like our can stabilizer last year or climber hook depositer this year).
1/8" aluminum plate, for most gussets (although this year we used 3/32 with a hole pattern to emulate a versagusset).
1/4" aluminum plate, for bearing plates and especially for when we used tapped plates. Beats using a nut and wrench in a tight space any day. Plus, it works great for screwing thing tubes together.
1/2" hex shaft for nearly everything. 7075 from Vex. We got a run of too-tight thunderhex, but apart from that I think it's great stuff.
pipsqueaker
26-03-2016, 09:17
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
Captain_Kirch
26-03-2016, 10:18
We use steel.
...
Takes up less room too. Can't imagine building in 1/2" tubes in aluminum. Would fold like tinkertoys. Steel is super strong.
...
Yes, steel is heavier, but we just use less.
Agree to disagree here. Aluminum is lighter and we use more of it. :)
We have had quite a bit of sucess with welded aluminum extrusions. We build robustly, and even in the toughest years for robot impacts (2014) we still have a robot to show for it. I think most of us remember how bad the hits got in 2014, but Jeffrey survived two regionals, Archimedes division, Einsteins, IRI, R2OC and Robofest. We're playing defense against our practice bot this year with that robot. Aluminum holds up if you have enough of it.
I don't think I've seen steel robots in this area though, its definitely unique.
We uses a lot of 80/20 aluminum to build this year and last...supplemented by Steel for bracing/shafts. Plus Polycarbonate and whatever comes in KOP. Spring steel here and there. Came in at a healthy 107 lbs usually we are at 120lbs. We used wood also for winch box.
As for aluminum grades, we pretty much follow the usual ways things are manufactured, and a bit of research after the fact showed this to be right in the vast majority of cases.
That is, you will notice that 6061, 6063, and 7075 are generally extruded and then tempered. Don't plan to put a sharp radius bend into any of these unless you're going to retemper. (and we don't have the faciilties).
5052 starts off stronger than any of the grades listed above, but does not add much strength in tempering. This is the material of the recent KoP chassis, Vex gussets, and Vex VF angle and c-channel. If we're going to bend some plate, this is our #1 choice. Even with 5052, be sure that you are bending around a radius about twice the thickness of the plate, and bend ONCE. Metal fatigue is another of the one hundred seventy three ways for a team to ill its own robot.
katabolt
27-03-2016, 00:32
Here at 3674 we build our bots with old-school AndyMark C-Channel. Sure it's heavy, but dang is it robust.
Michael Hill
27-03-2016, 08:41
This year, we used a lot of 1" x 2" 6061-T6 aluminum rectangle tube in both 0.125" and 0.063" wall. We also used a good amount of 1" x 1" x 0.125" 6061-T6 aluminum square tube. Our sheet metal belly pan was 0.063 6061-T6 aluminum and the impact "plates" were 0.063 2024-T3 aluminum sheets (stronger aluminum for where we could have potential impacts. We used self-adhering UHMW strips along the bottom of our robot to help us slide over the rock wall. Our drive shafts went from ThunderHex to just regular 0.5" hex 7075-T7351 aluminum shaft. We use a healthy amount of 0.25 6061-T6 aluminum plate for gearboxes, shooter rails, shooter, and pillow blocks. Our pickup mechanism plates were the same 0.25 plate. Our rollers were latex surgical tubing slipped on aluminum tube with a poor man's hex end caps (We lathed down some Vex 0.5" hex gears and pressed them in the ends of the aluminum tubes). We've got some polycord in our intake system as well.
Our hardware consists of mostly rivets, but there is a healthy amount of #10 and 1/4-20 hardware on there. We'll use mostly aluminum rivets, but there are some steel ones on there as well (for extra strength in a smaller size).
Team3844
27-03-2016, 17:39
We use stainless steel for 90 % or more of our bots construction. Our major sponsor manufactures commercial dishwashers. 3 years ago they volunteered to laser cut and fold all of our sheet metal with one condition, it had to be stainless steel so they could nest it in with their regular production. We use primarily 1/16 " I think 14 gauge with 1/8" 11 gauge for high stress parts. It makes a pretty bot. They usually make us 3 to 4 times the parts we need so we have a big collection of spare parts. I know most of you think the weight would be an issue, but by using thinner gauges and Swiss cheering at the design stage we come in comparable to aluminum. 105 lb in 2014, 120 lb 2015 mostly caused by a long wooden ramp and a over engineered lift, and 111lb not this year.
Attempting to synthesize all of the responses, it seems to me to come down to:
Take advantage of your expertise. Whether it's woodworking, monocoque, steel, sheet metal work, fiberglass, carbon fiber, or whatever, leverage it. Experts in any decent material can out perform people trying to wing it in the best available material. If you are so lucky as to have experts in multiple materials, may I suggest a bake-off? (and express a bit of envy, as well)
If your team does not have real mentor expertise in a construction material, aluminum (6061, 6063, 7075 extruded and tempered or 5052 sheet/folded) is a good place to start, with baltic birch plywood and sheet steel as alternates when aluminum doesn't fill the bill.
Poseidon5817
28-03-2016, 01:03
We use stainless steel for 90 % or more of our bots construction. Our major sponsor manufactures commercial dishwashers. 3 years ago they volunteered to laser cut and fold all of our sheet metal with one condition, it had to be stainless steel so they could nest it in with their regular production. We use primarily 1/16 " I think 14 gauge with 1/8" 11 gauge for high stress parts. It makes a pretty bot. They usually make us 3 to 4 times the parts we need so we have a big collection of spare parts. I know most of you think the weight would be an issue, but by using thinner gauges and Swiss cheering at the design stage we come in comparable to aluminum. 105 lb in 2014, 120 lb 2015 mostly caused by a long wooden ramp and a over engineered lift, and 111lb not this year.
We're pretty close to the same as you guys, main sponsor works in stainless sheet metal, so we do too. I think we used entirely 18 gauge, except for our shooter wheel mounts.
We did a pretty unique construction style this year.
For the drivebase we used large plates of 5052 sheet metal supported by 0.5x0.5" with 1/16" thick wall aluminum tubes riveted on at the edges.
The reasoning is that our team, where we machine everything in house, doesn't have access to a precision CNC break. We can't bend sheet metal accurately enough to construct a chassis out of it so we just riveted on tubes at the edges to strengthen the plates.
The shooter was constructed using 1x2" VersaFrames and lots more of 5052 plates, riveted together so that the channels were again at the corners and edges of the large plates.
Different student on the team have different design styles so our robot ends up looking pretty radically different each year (just my design style changed from 1x1 VersaFrame everything to 1x2 and large plates this year).
We used 1 1/4" c-channel for the majority of the build, but used the 1" tubing from the KOP for our arm. We did use a small part of the end plate of the KOP chassis, but otherwise, just c-channel.
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:
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.
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.
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.
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
28-03-2016, 14:27
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).
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"):eek: . Yes, they are pocketed....
garyklein
03-12-2016, 12:11
6061 robotextrusions and 5052 aluminum plate.
The extrusions are fastened with 10-32 socket head cap screws.
There are a couple drilling jigs available to locate and guide the drills and taps needed.
ThaddeusMaximus
03-12-2016, 12:24
We're pretty close to the same as you guys, main sponsor works in stainless sheet metal, so we do too. I think we used entirely 18 gauge, except for our shooter wheel mounts.
I pity your souls, having machined some stainless last year... although if you jet most everything, not as big of a deal.
JPBlacksmiths
03-12-2016, 12:58
We usually use one inch C-Channel aluminum for our chassis and for the rest of the robot we usually use one inch extruded aluminum and one inch aluminum square tubing. We occasionally use steel when more strength is needed, but we prefer aluminum for the price and weight.
Some people brought up welding as the best option for robot assembly, but we don't do that due to our limited budget. By bolting the majority of our metals together, we can take the robot apart and re-use some of the metal for the next year.
arc25565
04-12-2016, 19:29
Our team typically makes most of our robot out of 1"x1" and 1"x2" square aluminum tubing. We also use lots of 90 degree 1"x1" angle and 1" by 1/8" bar. Everything is 1/8" thick. I find that if you go much thinner than it is really easy to over tighten things.
Mr. Ackroyd
05-12-2016, 10:50
Last year our team went with 5052 1/8" sheet aluminum and 1"x 1" x 1/16" aluminum tubing. We also used churro bar for standoffs and turned down aluminum round stock. Our team has always incorporated aluminum welding as we have had mentors in the past train students. however, this year we had a specialist from the Navy come in and really train the kids as we had some tricky areas. We are lucky enough to have mills and lathes to take down our parts when needed.
Last year we had a local college (RPI) water jet our plates and that helped out tremendously. This year we picked up a CNC plasma cutter and plan to cut all plates with that machine. So we will be building our entire robot in house.. We also plan on making parts for local teams when needed.
Anna F15H
05-12-2016, 15:26
We use an aluminum extrusion called Item. We typically make our frames out of the 20 mm x 20 mm and 20 mm x 40 mm options. It is very convenient for making quick adjustments with T-nuts without drilling lots of new holes every time we want to move something. I've never experienced any issues with it bending or losing its structure.
Mike Schreiber
05-12-2016, 15:58
6061 should never be used in a bent piece. The metal has a interesting habit of cracking and "exploding" when bent in a break.
Our frame was 0.060" 6061 last year. You can bend it fine. Until 2016 we've generally used 5052, but it's certainly doable with 6061. I'm not sure what temper we get, that might make a difference.
3928 also uses 6061 bent sheet metal. We use 1/8" metal which is bent and cut by one of our sponsors (http://www.qualitymfgcorp.com/). You can definitely bend it if you have the appropriate tools to get a larger bend radius (we use 7mm). It is extremely strong, even though we lighten it pretty heavily.
Our 2016 shooter (https://www.flickr.com/photos/frcneutrino/25004472935/in/album-72157663280596052/) frame (https://www.flickr.com/photos/frcneutrino/25204562425/in/album-72157664410619730/) is a good example of what you can do with it.
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