Robot Arm C

[twototwenty]

Out of curiosity, what are people building thier frames out of? I have yet to find a good set up which is the right size, but not too heavy and cumbersome.

[harryk]

Out of curiosity, what are people building thier frames out of? I have yet to find a good set up which is the right size, but not too heavy and cumbersome.

Carbon-Fiber FTW

[twototwenty]

Really? How much did that amount of carbon fiber cost you?

[jander14indoor]

$36 for a 3/4 inch carbon pultruded tube, 48 inches should do you. From a REAL quick search.

Jeff Anderson
Livonia, MI

[harryk]

I got 1"x12" pieces for about $5 each

[scm424]

Where might a beginner learn how to build robots?

[twototwenty]

If you are a complete beginner, I would recommend getting the owi kit, espescially if you don't have much to spend, builing it with the instructions, then designing the necessary extensions for it to make it long enough. My team did that, and it ended up placing 3rd at my regionals, and that was with minimal practice. Of course, this only works for lower levels of the competition.

[mrsteven]

Where might a beginner learn how to build robots?

I'm still learning as I'm going. depending on how in depth you want to go with the design from a basic one to a more complicated requires-coding type systems. To my knowledge there isn't a singular guide to help but if you know some principles and basic idea on function, many schools engineering teachers will help you figure out how to assembly logistically and if required, help with coding

OWI is what I started off with, it can be very helpful with learning the ideas of how one should function to abed further development. Also if you really want to you can steal the board from it and use the controls with another bot with similar motors

[twototwenty]

What strength (torque) servos are you guys using, in particular for the "elbow", "shoulder" and overall rotation joints?

[iwonder]

If properly counterweighted, I've used the HS-645MG(133oz in) for the secondary axis(elbow), and could possibly use it for the primary, however I use a HS-805MG in a geared configuration for the main axis(shoulder) which is rated at 1715oz in of torque, this is a little crazy for a normal sized arm, but mines about twice the size it needed to be . I use another HS-645 in the base, but I've shredded the gears twice(small gear teeth...) and before I broke the mechanical stop on a karbonite servo(HS-485HB). I do have an HS-7950TH that I've put in the base and it works well(a little overshoot, but the servo controls it) that is rated for 402oz in@6v(titanium gears) however it's not very smooth to control so I can't use it in competition.