Monthly Archives: May 2017

Center Foot Upgrade – huge improvement

Finally got tired of the single caster in the center foot. My droid is styrene (Dave Everett’s plans) so it weighs just 89 lbs. Its been a solid droid for the last two+ years. However, you can see in the video it does not do well on cracks/lips so door transistions, sidewalks,etc are a nightmare. Decide to go with the vex setup using Kevin Holme’s bracket, added additional brackets so that its all metal from the center ankle bolt down. Then used Michael Baddeley’s center foot 3D model, and modified it to fit my custom setup using Fusion360.  The new center foot adds 3.5 lbs so now it weighs 92.5 lbs.

Printed the foot at 15% infill / 4 layers / 0.25 layer height, and then printed the sides at 15% infill / 4 layers / 0.1 layer height to smooth out the curves of the half moons. The left side is glued on, the right side is held on by magnets (mounted in the insets). The foot is solid!
There is access to the bolt to install/remove the bolt (and its large enough for a socket to fit over the bolt head), plus there is a hole for a screw to lock the ankle/foot, it also includes a slot for a washer and the nut.
The video shows the clear difference between the two. Now just need to prime/sand/paint and it will be show time! Also thanks to Greg Tracy for the huge assist on my build in the first place.

 

Parts List:
Wheel Assembly
Kevin Holme’s bracket – $35  http://holmemadeparts.com/Front-Foot-Vex-Wheel-Bracket-Vex-Plate.htm
4 – 4″ Omni-Directional Wheel – part #217-2584 – $18/each – $72  https://www.vexrobotics.com/vexpro/motion/wheels-and-hubs/omni-wheels.html
4 – Flanged Bearing – 0.375in x 1.125in – part #217-2732 – $3/each – $12  https://www.vexrobotics.com/bearings.html
1 – Angle Bracket (Lowes) ML24-TZ 2″x2″x4″  (cut in half) – $2 https://www.lowes.com/pd/USP-2-in-x-2-in-x-4-in-Triple-Zinc-Angle/50325313
2 – 3D Printed 0.5″ versahub
2 – 3/8″-16, 3.5″ long bolt – part# 91257A639 – $1/each – $2  https://www.mcmaster.com/#91257A639
2 – 3/8″ washers
2 – 3/8″-16 Locknut, heavy vibration – part# 94820A242 – $1/each – $2  https://www.mcmaster.com/#94820A242
6 – #6-XX, XX long screws, through VEX wheels to tie together
4 – #10-1/2″ bolts
4 – #10 nuts

Center Ankle Bolt
1 Shoulder Screw – part# 94496A540 – $7  https://www.mcmaster.com/#94496A540
1 3/8″ Washer
1 1/4″-20 Nut

3D Print Files:

Center foot
Left Side
Right Side
Top Cap