Gears robot

diy
http://www.diy-review.com/scuPDHowToHENfs0/Plastic-ball-bearings.html plastic ball bearing

Hour glass
http://www.kinematicsmfg.com/quality/hourglass-technology/ (Scan design with laser scanner and reproduce 3d printer) Kinematics’ patented hourglass design is unique because it can withstand a survivability load that is four to nine times greater than loads carried by typical slewing drives. The special hourglass shape of the drive allows more teeth to be engaged at one time, enabling much higher torque endurance. Our technology delivers a stronger and more durable drive so your equipment can perform longer and more reliably.

plastic ball bearing
http://www.youtube.com/watch?v=0sfNEHDPucs xiros Free from maintenance and lubricants, suitable for extreme environments

Xiros plastic ball bearings from igus are designed for applications where the use of grease or lubricants is prohibited. The food and drinks industry, in particular, bans the use of such substances altogether. The design of igus xiros ball bearings is the same as conventional steel bearings, consisting of an inner and outer race, a cage and a number of balls; the only difference being that the races and cage are made from igus tribological polymer materials. These plastic materials are self-lubricating and thus negate the need for lubricants. http://vimeo.com/63738557

http://www.igus.co.za/wpck/default.aspx?Pagename=ballbearing&C=IL&L=en

http://www.youtube.com/watch?v=ub-3kjljf-o 3d printing ball bearings 0

http://www.youtube.com/watch?v=GJtRKDhfnqo  printing gears 1

http://www.youtube.com/watch?v=ehnzfGP6sq4 printing house

d
http://www.sdp-si.com/

http://www.econobelt.com/

http://www.khkgears.co.jp/world/RCandROBO.html

http://www.robotmarketplace.com/products/wheels_main.html  Wheels

http://prosafesecurity.co.za/catalog/58  Bevel gears for gates

Worm gear
http://www.thingiverse.com/thing:8821 Description

Ok, once you have an involute gear library AND a trapezoid thread library, you can easily make the simplest of worm drives, i.e. the non-throated kind.

Like all worm drives, the gear advances by one tooth for each revolution of the screw but with non-throated ones, there is only a single point of contact at any one time, and so torque and wear capabilities are limited.

UPDATE: As I pointed out in the comments, AFAIK a trapezoidal profile for the worm screw is all you need to match the worm gear's involute.

To make them mesh, all I did was to make sure that: 1. the pitch is the same (distance from crest to crest), 2. the pressure angle of the gear is equal to the angle of the sides of the screw profile, 3. the distance between screw and gear is equal to the gear's radial pitch plus the screw's mid-profile radius, and 4. the twist on the gear is equal to the gear's pitch radius divided by the screw's mid profile radius, with a sign depending on the screw's handedness.

ball screw
http://www.thingiverse.com/thing:112718/#comments threadless ball screw

Universal joint
Traxx company rc model http://www.youtube.com/watch?v=G5El9UynAFc