2020 Carriages for Zero-Backlash Magnetic Arms

These carriages work for 2020 aluminum extrusions and 24mm diameter wheels, such as the ones from OpenBuilds or RobotDigg.com.
Eccentric spacers are used for preloading the tension on the wheels.
You can get the ball studs from me for $1 each, and I also precisely build the carbon fiber, zero-backlash, magnetic arms. My website is http://www.MagBallArms.com

This design works nicely with my effector which sports an LED light ring and 3 PLA cooling fans: http://www.thingiverse.com/thing:1546124

Here are links to the wheels, eccentric spacers and 1/4" round spacers from RobotDigg:
http://www.robotdigg.com/product/521/Delrin-or-SUS-Via-S-Bearing
http://www.robotdigg.com/product/626/Openbuilds-decentration-post
http://www.robotdigg.com/product/670/Spacer-for-Delrin-Slide-Kit

Here are links to the wheels, eccentric spacers and 1/4" round spacers from OpenBuilds:
http://openbuildspartstore.com/delrin-v-wheel-kit/
http://openbuildspartstore.com/aluminum-spacers/ (choose 1/4")
http://openbuildspartstore.com/eccentric-spacer/ (choose 1/4")

Per carriage, you will need:
3 of the above V- or W-wheels.
2 of the above 1/4" spacers (or you could use 6mm).
1 of the above 1/4" eccentric spacers (or you could use 6mm).
3 M5x35 bolts.
1 large M5 washer for the top side of the eccentric spacer (optional).
3 M5 nylock nuts to secure the three axles.
2 3/8" ball studs.
2 M3 nylock nuts to secure the ball studs.
2 M3x35 SHCS for the tightener.
2 M3 nuts for the tightener.
1 M3x20 SHCS for the vertical post for the upper G2 belt attachment.
1 M3 nut to secure the vertical post.

Note: You should be able to easily alter the OpenSCAD source to work with 2040 or 2060 extrusions, by changing extrusionWidth from 20.0mm to 40.0 or 60.0mm.

If your belts are farther above your carriages, you can easily adapt by using a longer M3 vertical screw.

The belt tightener this uses is very simple and easy to adjust with two M3x35 screws.
I found that this delivered better results than using zip ties. My prints got more accurate by about 50 microns.

I also have a version for 15mm diameter "mini" V-wheels: http://www.thingiverse.com/thing:2183355

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