Servo - December 2013

different attachment method. These wheels are designed to be used directly on a keyed half inch shaft.

If you want a durable wheel that can be run directly off of a gearbox, it's a very good option. The size and weight make it an option mainly for the 30 lb class,

however, it would be possible to use it on a

12 lb robot.

FingerTech Sumo Wheel

Diameter:

1. 75-3 inches

Tread Width:

1.5 inches

Weight:

61 g-178 g

Cost: $15.70-

$31.32

Comments:

As the name suggests, these wheels are primarily meant for Sumo competitions.

They're available in two durometers (20A and 45A) and multiple bore options ( 3 mm-1/2 inch), and can have a keyway cut in them at larger bores. The smallest class these could be practically used for is the 3 lb class, however, they have been used in the 30 lb class in the past.

If you intend to use these for combat, a plastic insert could be added to the open side of the wheel to help dissipate the forces from any impacts the wheel sees to the shaft in a way that will reduce the chances of bending. While the 20A wheel option would provide fanastic grip, if you do choose to use these the 45A option will likely be much more cost-effective in the long run.

FingerTech Mini Sumo Wheel

Diameter:

1.125 inches

Tread Width:

0.85 inches

Weight: 12. 6 g

Cost: $18.48-

$20.48 (pair)

Comments: The Finger Tech mini Sumo wheel was originally designed for their Mini Sumo kit; however, the high grip tread and lightweight construction make it an attractive option for 150 g- 3 lb robots. If you're using the wheel on one of their Spark gearmotors or any other gearmotor of the same or smaller diameter, you have the option of having the wheel extend over a portion of the gearmotor. If the gearmotor is robust enough, this can allow you to build a much more compact drive system without sacrificing too much durability. However, this will likely block off the gearbox mounting points and may require creative mounting solutions.

Lite Flite/Lectra Lite With Lite Hub

Diameter:

1. 5-5 inches

Tread Width:

0.445-1.5 inches

Weight: 1.2 g (hub only)

Cost: $4.62

(pair, hubs only)

Comments: This combination is one of (if not) the lightest wheel option for the 150 g- 3 lb classes. With this arrangement, you take a stock Lite Flite or Lectra Lite wheel (except for the 1.5" Lite Flite, which needs to be bored to 5/32" from 1/8") and insert the hub, applying glue as it slides on. If the wheel is mounted externally, placing the hub on the outside will reduce the chances of the wheel being ripped off of the hub. However, this puts the shaft in greater danger of damage. The only downside with this hub solution is that you can't re-use it when the wheel is either worn or damaged beyond use. So, if your bot is prone to wheel damage, you'll want to keep a stash of spares available.

Lite Flite/Lectra Lite With Snap Hub

Diameter:

1. 5-5 inches Tread Width: 0.445-1.5 inches Weight: 6 g- 7 g (hub only) Cost: $14.78 (pair, hubs only) Comments: The Finger Tech Snap hub is their more robust