Materials

When building your robot you must realize that not every material is good for everything. Some jobs call for titanium while others call for lexan. Here is a table of varios materials an alloys along with what they're good and bad for.

Material	Alloy	Density	General Properties	Good for	Bad for
Aluminum	6061	0.098 pounds/cubic inch	Fairly soft compared to steels, but fairly strong for aluminum.	Frame, baseplate, bearing blocks, motor mounts	Killsaw armor (though some argue that the saw teeth will get caught and throw you, doing little damage)
Aluminum	7075	0.101 pounds/cubic inch	A little harder than 6061, but a bit more brittle. Cannot be welded.	Frame, baseplate, armor	Any application where a good ammount of flexing is requred, anything that needs to be welded
Aluminum	FORTAL	0.10 pounds/cubic inch	A trademarked aluminum alloy that has properties similar to 7075. Not weldable	Light drive axles, bolt-together frame.	Spinning discs (has been known to crack).
Aluminum	ALusion	Varies dramatically	A stabilized aluminum foam that can be made to any density between 90% air to 90% aluminum. Soon to be available from BotParts	Ablative armor, frame, mounting brackets.	Standard armor, lifting mechanisms.
Magnesium	AZ31B	0.063 pounds/cubic inch	Similar to aluminum, but more brittle. Main advantage is it's obscene lightness.	Lightweight frame, baseplate	Killsaw armor, normal armor, heavyweight frame
Steel	C1095 spring steel	0.283 pounds/cubic inch	Obscenely hard and difficult to cut. Only available in very thin sheets and is not weldable.	Killsaw armor, lexan overlay protection	baseplate material, standard armor
Steel	S7 tool steel	0.283 pounds/cubic inch	Very VERY tough metal that can take extreme impacts without deforming or cracking. Properties similar to mild steel in its normal state.	Weapon impact teeth, hammers, spikes.	Most armor applications or large sheets. Needs to be heat treated for maximum strength(reccomended hardness: 55rockwell).
Steel	AerMet 100	0.283 pounds/cubic inch	One of the strongest materials in existance. Breaking strength DOUBLE that of 6al-4v titanium	Lifting/crushing mechanisms, extreme load applications.	EXPENSIVE, extreme strength not necisarily needed for all applications.
Steel	4130 chromolly	0.282 pounds/cubic inch	High tensile strength steel alloy that can take impacts well. Commonly found in thin-walled round tubing. Welds nicely. Must be heat treated to gain advantages over mild steel.	Weapon impact teeth, frame, thin sheets as armor.	It's a bit overkill for mounting brackets.
Steel	316 Stainless	0.287 pounds/cubic inch	A high performance stainless steel alloy with a tensile strength higher than 6al-4v titanium.	Armor, frame, impact teeth, fasteners.	Brackets and mundane things.
Steel	1144 stressproof	0.283 pounds/cubic inch	Fairly strong steel commonly found in round bars.	Drive and weapon axles, frame.	Armor
Steel	1018 mild steel	0.283 pounds/cubic inch	Cheap, moderately strong, easily workable steel alloy.	Good for first robots frames, armor, and just about anything else.	It IS steel, so it IS heavy. Just be smart
Titanium	6al-4v	0.163 pounds/cubic inch	Very hard, very tough. can take big impacts without deforming.	Armor, frame material, baseplate, killsaw armor	mounting brackets
Titanium	CP	0.163	Commercially Pure titanium. Not nearly as strong as 6al-4v. Strength comparable to mild steel.	Armor, baseplate, Frame	hard to find in blocks to make mounting brackets.
Titanium	LiquidMetal	0.17 pounds/cubic inch	Amazingly tough, impact resistant metal that does not have a melting point but rather the viscosity descreases gradually with temperature like a thermoplastic	If you have access to this stuff, just about anything.	Anything where some sort of budget is required. The material is 15 dollars/pound for THEM to make, and several times that for you to buy.
Plastic	polycarbonate (lexan)	0.0434 pounds/cubic inch	Very soft and easily cut, but can take big impacts without deforming.	Light mounting brackets, impact-absorbing armor	Frame, killsaw armor
Plastic	UHMW	0.0344 pounds/cubic inch	Very soft, but will only bend and stretch, not crack.	Mounting brackets, shock absorbtion, internal stuff	armor, baseplate, killsaw guards, just about anything external.
Plastic	Urethane	0.047 pounds/cubic inch	An extremely versatile plastic that can be made as hard as a golf ball or softer than rubber.	Typically used as wheel tread and casters. High abrasion resistance.	Bad difficult to use for other purposes
Plastic	Acrylic	0.0434 pounds/cubic inch	A versatile plastic that can be made in many shapes and colors easily.	Not much. It's generally far too brittle to use in combat applications.	Robot promotional poster holders...
Plastic	Acetal (delrin)	0.0514 pounds/cubic inch	A fairly tough plastic with strong self-lubricating properties.	Skids and other low-friction applications, mounting blocks.	Can crack easily as armor.

Let's talk materials, shall we? We here at Team STUPID are very fond of Aluminum. Pound for pound there aren't many materials stronger than it. Titanium probably is (pound for pound) but it's expensive. For the inexperienced robot builder with a fairly low budget, steel can't be beat. It's cheap as dirt, strong, and easy to weld. It's heavy, but it'll get the job done. For your frame, we strongly reccomend investing in welded aluminum tubing done by a professional. Because it is light, you can afford to use a very thick-walled pipe (both Strange Brew and Chester use 1 inch OD 5/8th inch ID round 6061 aluminum pipe for the frame) without adding any more weight.

Now a lot of people have a titanium "fetish" if you will. Titanium is NOT good for everything, contrary to what many believe. Titanium is fairly hard to weld strongly, it is in limited availability, and though lighter than steel it is still heavy. Titanium isn't super-hard and uncuttable, it is very TOUGH. Titanium can bend very far without breaking, much like Lexan. It, however, is very difficult to bend and keep bent for rounded parts. Also Titanium armor + a saw = big pretty white sparks that could indicate more damage than was actually inflicted. It is hard to form into shapes and is expensive as all hell, even surplus. It's very good against piercing and impact weapons and good against saw weapons.

Now we come to the great killsaw debate. I will discuss the four materials most commonly used to guard against the arena killsaws and their plusses and minuses. First is Aluminum. The alloy here is irrelevant, all aluminum is fairly soft but this comes as a mixed blessing. If your robot is held in place over the saws by, say, your opponent, it can be cut through without much trouble. If the opponent is not there, the robot will likely be thrown from the saws because the teeth dig in and toss. Aluminum doesn't spark, so not much visual damage is caused. This is rather null and void if your robot is a super-heavyweight because the sheer mass of your robot will likely cause it to stay on the saws unless you drive off. It is more or less the same with Lexan, just more so.

On the other hand, the harder materials such as titanium and steel will simply slide off of the killsaws because they cannot dig in and throw/cut. Both steel and titanium DO however make sparks which can appear to be much more damage than actually is occuring. Both materials are, however, much heavier than aluminum and polycarbonate. Titanium is lighter than steel, but produces more dramatic sparks.

Every material has it's own plusses and minuses. You yourself must balance these to determine what would be best for what. Godspeed, my minions!