What kind of material will you be using for your arm/forklift?
 

Alright, you have your designs drawn and a some type of base built. Your ready to start constructing that beefy arm you've been dreaming up all week. My question to you is this what kind of material will you be using to get the strength you need with conserving as much weight as possible.

Re: What kind of material will you be using for your arm/forklift?
 

We are planning on a 4x4 1/8" thickness aluminum rectangular tube with serious trussing in it (40% of mass removed). I have seen several arms like this, and they looked plenty beefy.

Re: What kind of material will you be using for your arm/forklift?
 

Yea are main concern is weight but we have found a way out of that. We have our drive train built and with base transmission wheels compressor tanks and other basic stuff we are looking at or around 60lbs. So aluminum is out of the picture for us but it worked great last year.

Re: What kind of material will you be using for your arm/forklift?
 

Our team is looking towards the plastics as our friend for this task. We have some modified plastic material that could prove to be plenty strong.

Re: What kind of material will you be using for your arm/forklift?
 

Why is aluminum out of the picture for you?
Almost all arms I have ever seen have been made from aluminum. Whether is be angle aluminum, extruded aluminum (80-20), aluminum box tubing, or aluminum round stock.
From what I read I think you mean using a heavier stronger material such as steel. There is no reason at all to make part of the arm (or the whole) steel. It needs to move (apparently) and the lighter it is, the easier it is to power. I also think that the forces on your arm are not going to be any where near enough to require it to be made from steel. Proper use of aluminum does wonders.

Re: What kind of material will you be using for your arm/forklift?
 

Right now our arm is being designed with aluminum. But the extrusions that its made of are very common. It could be switched out for other materials as long as they come in the general shapes(square, C, L, etc.).

Re: What kind of material will you be using for your arm/forklift?
 

Most likely the team will use square aluminum tubing. It proved plenty beefy last year.

Re: What kind of material will you be using for your arm/forklift?
 

As of now we are looking at 80/20 extruded aluminum.

Re: What kind of material will you be using for your arm/forklift?
 

like last year our frame is made out of Chromali. Light as aluminum but much stronger... although very expensive.. i dont even know how we paid for all of it but thats what were using this year for the frame and the prototype made now also has the arm made out of that.... we need as light as possible because of all the weight from our pneumatics. we have 3 or 4 pistons to run through out the match so its gonna be heavy

last year we used triangular aluminum for our telescopic arm... idk if any of you noticed our robot last year? midwest champs? #269

Re: What kind of material will you be using for your arm/forklift?
 

We are planning to use 2" ID aluminum tube. Seems very stiff, and is also very light. McMaster Carr sells it.

Re: What kind of material will you be using for your arm/forklift?
 

Antimatter.. It will help us in the never ending quest to build the bot under the weight limit. :)

Re: What kind of material will you be using for your arm/forklift?
 

Either Al square or thinwall steel tube

Re: What kind of material will you be using for your arm/forklift?
 

Tell me more about this material. One of the kids on our team has a dad that manages a composites manufacterur. So we have been looking at some different things including carbon fiber and some other composites. Please weight is always a problem for us and we cannot afford to use alluminum this year. This is why i created this thread was to see some different composites and alloys.

Re: What kind of material will you be using for your arm/forklift?
 

I think he might have been referring to "chrome-moly," which is a steel alloy of iron, molybdenum, chromium, and sometimes manganese. It's a common material in high-end bicycle frames, especially in Italian or custom-made bikes. It is heavier than aluminum, per unit volume, but has better ductility, and can be brazed or welded. The lightest bicycle frames now are composites, but right behind those are aluminum and chrome-moly. It's been a few years, but a favorite chrome-moly tubing around 1970 was Reynolds 531.

Most carbon fiber composite parts are mind-bogglingly expensive. I would be interested in hearing more about how you are thinking of fabricating composite components.

Re: What kind of material will you be using for your arm/forklift?
 

Aluminum extrusion with 24" drawer slides for a telescoping arm. Still being built. We'll see.

Re: What kind of material will you be using for your arm/forklift?
 

1.5" square x 1/8" aluminum with some major drilling going on to it. Not too much on our arm so it should be plenty strong.

Re: What kind of material will you be using for your arm/forklift?
 

For the second year we are using some 1 and 1.25'' aluminum tube with 1/16 wall.enough to It was strong enough to lift our robot last year and is really lightweight. It is not the easiest of things to work with because it is round, but it would be rigid enough to do anything you need to do.

Re: What kind of material will you be using for your arm/forklift?
 

We decided to just go all out this year. You can either come to play or just go home.

Part 9081K696 from McMaster was the first thing we ordered at kickoff.

Matt

Re: What kind of material will you be using for your arm/forklift?
 

He lies!

9081K696
(Same as 9081K69)Titanium Grade 5 Rectangle 1" Thick, 3" Wide, 6' Length$2,274.36 Each. Usually ships within 1 week.

:p

Re: What kind of material will you be using for your arm/forklift?
 

If they only use about 8% of its length, can they prorate the cost? :p

Re: What kind of material will you be using for your arm/forklift?
 

Our team has decided to use this for the arm this year. We haven't tried it out yet, but we are pretty sure it is the way to go. Have any other teams had any success using this stuff? I think eventually FIRST teams will start to catch on and you will see this stuff all over robots in the future.

Re: What kind of material will you be using for your arm/forklift?
 

That is awesome stuff. It is the wierdest thing I have ever held. With your eyes closed, someone could set it in your hand and you would never even know. I think it goes just a smidget over the cost limit though. :)

Re: What kind of material will you be using for your arm/forklift?
 

Carl, I'm embarrassed that you're in the same major as me at Purdue. You really annoy me sometimes, for stating such obvious things like this.

Seriously, it's obvious that every good team will be using it. We're using it to build our chassis and even using some wire EDM to cut spur gears out of it. (Only for the initial stages of the gear train, using hardened steel in the later ones of course.)

Chief Delphi is only supposed to be used for important engineering discussions, not discussing obvious material selections. I can't believe you're going to be my roommate next semester. :ahh:

Matt

Re: What kind of material will you be using for your arm/forklift?
 

Matt, I agree that it would make an excellent chassis material but I don't see any way you could possibly make gears out of it. Do you understand the forces on the teeth of these gears? I think you've been breathing aerogel fumes too long. You will be better off making your gears out of some grade 5 titanium. I hear McMaster stocks that stuff.

By the way, does anyone know the coefficient of friction of aerogel on carpet? Thanks.

Re: What kind of material will you be using for your arm/forklift?
 

Ugh, I just reran the numbers. No, you can't use it on gears unless you have a pitch of about 4. I looked into the titanium. Good call.

After that I went back to the lab did some quick tests of the Aerogel on a FIRST carpet sample and got about 1.1 or 1.3. I didn't think about using it on wheels. Again, good call.

I take back my harsh comments from before. I'm glad that you're a Purdue engineer. I just wish you could be on the cool FIRST team that Purdue sponsors instead of that old school one. I'll forgive you.

Matt

Re: What kind of material will you be using for your arm/forklift?
 

Matt, Carl,

You sly dogs... you have us thinking that you are using this Aerogel stuff, but all the while you are using nanotubes. I mean, heck, all you have to do is walk across campus and grab a wheelbarrow full of the stuff. Sheesh.

Andy B.

Re: What kind of material will you be using for your arm/forklift?
 

I think this thread should officially be renamed, "Purdue Sponsored FIRST Team's Secret Materials List - Revealed!"

I guess it's my fault. I started talking about our titanium arm, then Carl piped in about the Aerogel, and then Andy dropped our biggest secret - the nanotubes.

I openly confess that the new nanotechnology engineering park they're building is actully just to ensure that Purdue sponsored FIRST teams get a massive edge with their building materials. The secret it out.

Too much has been said already...

Matt

Re: What kind of material will you be using for your arm/forklift?
 

For those of us without access to unusual materials, I posted a spreadsheet for figuring out what materials in McMaster-Carr might be appropriate. Here's the link: http://www.chiefdelphi.com/forums/pa...le&paperid=427

Re: What kind of material will you be using for your arm/forklift?
 

CABLE TRAYS!!!

One of our sponsors is a supplier for "cable trays" which are aluminum, well, trays with the sides bent up--great for extending arms. plenty beefy too, we used 'em last year for hanging, and they held all 130 lbs of bot! :yikes:
Thank you Globe Pacific!

(pst! wanna see some cable trays? go to one of those parking garages in your downtown area, and look up. they'll probably be all over the place to organize wire distribution over the building. and in the garage they're not hidden by the ceiling. ;) )

~Stephanie
Team 1351

Re: What kind of material will you be using for your arm/forklift?
 

Thats awesome. Very clever yea we just posted our first teaser (cough cough) we have a good idea for our arm including a few different materials one of them being aluminum.

Re: What kind of material will you be using for your arm/forklift?
 

beefy? i dont understand? there's something that starts with center and ends with gravity, which is why those purdue guys are cuttin' the fat.

Re: What kind of material will you be using for your arm/forklift?
 

c'mon you know with that first week of dreaming some of the outrageous concepts you come up with. you know the ones that weigh 1/2 ton and can move in any direction 40 ft. thats wat i meant by beefy but some arms do tend to be a little large. Aluminum does seem to be the favorite. This, I would guess, is because its fairly abundant, very strong, light compared to steel, and easy to fabricate. Therefore making it the logical choice. This is FIRST, logic is out the window.

Re: What kind of material will you be using for your arm/forklift?
 

Most of you think you can't make a good arm out of raw superstrings, but we've figured out a way to hold them in place with resublimated thiotimoline. We looked into using scrith, but it was too expensive.

And, believe or not, we buy superstrings by the pound at Harbor Freight! We know the best superstrings come from California, but we've been successful with Guamian imports.

Re: What kind of material will you be using for your arm/forklift?
 

We were thinking about using a helicoptor rotor drive shaft. That is awesome stuff, really strong and insanely light (a 10 foot tube weighed about 5 pounds to my guestimate). One of our sponsors is American Aircraft Products. We ditched the idea because we weren't 100% sure if it was legal and 2 inch square tubing that's hollowed out would work just fine.

Also used:
Spring Steel
3/4" diameter 1/8" wall circular tubing
1/4 and 1/2 inch plates
1x2 and 2x2 square tubing
1/16" sheet metal

And finally, nanotubes :D

Re: What kind of material will you be using for your arm/forklift?
 

Team 814's arm will be made out of both angle and box alluminum, and a team Dad has donated a 4'10" rod of carbon fiber! It's teh awesome.

Re: What kind of material will you be using for your arm/forklift?
 

Team 716's arm will consist primarily of U channel aluminum, and some UHMW polyethylene.
Slides nicely. :)

We have also grabbed a few pieces off of a snowblower...
...but what they are and what their purpose is has yet to be revealed. ;)