Robot arm material

[A00620968]

Hey every one ill keep this short and sweet

Im thinking of making a 3DOF robot arm and am trying to figure out what to use as material for the arms (strong but lite) my ideas as of yet are
1. 2 carbon fiber rods in parallel (like the bond in your fore arm)
2. 2 aluminum rods (same as above)
3. lexan or acrylic rods

any other suggestions would be appreciated

[wil.hamilton]

i would go with the lexan or acrylic simply because it is easy to work with.
then from there aluminum. 

carbon fibre would be the lightest, but the hardest to work with

[A00620968]

Do you know what kinda of strength carbon fiber has when it comes to bending?

[Razor Concepts]

Very very high - CF is known for its stiffness.

I don't see how carbon fiber is the hardest to work with. You can saw, glue, cut, etc just like anything else - even easier than aluminum.

[SmAsH]

how long will it be and how much weight will be put on it (max)?
if the forces aren't to strong you could consider plastics...
carbon fibre is easy to work with, never worked with it personally but have mates who have.

[madchimp]

I would lean towards the carbon fiber. If there are any archery shops around you, check with them they might have cheap carbon arrow shafts that would fit the bill. They might even have carbon arrows on their way to the trash they would be willing to give you. The cheap ones will work you don't need expensive ones the main difference between expensive carbon arrow shafts and the cheap ones is how straight they are and weight. For a robot arm the differences would not be noticed. I have some carbon arrow shafts that were given to me because they got new arrows and since arrows are cut to size their resale is limited. I plan on using them in a robotic arm once I have the funds and time to work on it.

[Joker94]

i have worked with carbo fiber a bit and it is easy to work with

check this outhttp://www.societyofrobots.com/materials_carbonfiber.shtml

if the load that is wanting to be achieved is not that heavy, lexan or acrylic is probably more practical, and cheaper.
But if you want to and have the power to lift heavier loads go with CF as it is strong and i find easy to work with

[Admin]

You need to do a stress analysis . . . either simple beam analysis deflection equations, or fancy pancy FEA that I do on my robots.

Thats the only way to know without buying and experimenting . . .

Oh and you probably want 3 rods in parallel to handle lateral loads, not 2.

[madchimp]

You need to do a stress analysis . . . either simple beam analysis deflection equations, or fancy pancy FEA that I do on my robots.

Thats the only way to know without buying and experimenting . . .

Oh and you probably want 3 rods in parallel to handle lateral loads, not 2.

Yes or the robot gods will strike you down! This isn't really a need! does it make the bot better? Of course since you will make better use of materials you can have the strength you need without extra weight. However there have been many really cool things built that the builder didn't do any stress analysis before hand.

[gaurav.p]

yup i agree and stress analysis is very expensive and needs a lot a computer requirements(i think)

-gaurav

[Admin]

Non-fancy stress analysis can be done by hand in 5 minutes.

Of course you can guess the design, but if it doesn't work, you'll have to do it again, and buy material again

http://www.google.com/search?q=calculate+beam+deflection

[gaurav.p]

thnx i didn't know that can be done