Ball Caster Metal - 3/8"

This ball caster kit from Pololu includes a black ABS housing, a 3/8" diameter metal ball, two spacers (1/16" and 1/8" thick), and two #2 screw sets.

The total height of this ball caster is 0.4" with no spacers. You can also adjust the height by adding the spacers.

The ball caster can be mounted to a chassis by the two screw sets included in the kit. The distance between the two screw holes is 0.53".

Ball Caster Metal - 3/8" Product Help and Resources

Resources & Going Further

Or check out this example using a Raspberry Pi, RC LiPo battery, and TB6612FNG DC motor driver.

Core Skill: Robotics

This skill concerns mechanical and robotics knowledge. You may need to know how mechanical parts interact, how motors work, or how to use motor drivers and controllers.

1 Robotics

Skill Level: Noob - You will be required to put together a robotics kit. Necessary parts are included and steps will be easy to follow. You also might encounter basic robotics components like bearings, mounts, or other hardware and need a general idea of how it goes together.
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Core Skill: DIY

Whether it's for assembling a kit, hacking an enclosure, or creating your own parts; the DIY skill is all about knowing how to use tools and the techniques associated with them.


Skill Level: Noob - Basic assembly is required. You may need to provide your own basic tools like a screwdriver, hammer or scissors. Power tools or custom parts are not required. Instructions will be included and easy to follow. Sewing may be required, but only with included patterns.
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Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • Could this replace the plastic stabilizer on the new Shadow Chassis? Is the back of it sticky in any way? Thanks!

  • chartle / about 12 years ago / 2

    Any reason to use this one over the plastic one besides weight?

  • Member #670023 / about 9 years ago / 1

    Anyone know of any ball-and-sockets with sensors in them telling you the rotational position? This is the design I would like to have, but I would like to take readings from the position my object is in.

  • Jon990 / about 11 years ago / 1

    Great low-friction skid surface for a 10-20 pound robot. We used it for a line-following robot which drove on a smooth, perfectly flat, white MDF surface marked with thick black PVC tape. The robot was able to perform tank-style turns reliably, and the added spacers ensured that there was little wobbling. Small washers could also be used as spacers if the included ones aren't the right thickness for your application.

  • ET3 / about 11 years ago / 1

    Do you have a weight of this unit handy ( without the spacers + weight of one spacer) ?

    • ET3 / about 11 years ago / 1

      Nevermind... got it in the mail. For those who want to know ( like mini sumo builders) 4.8 grams for the caster, nuts and bolts. .3 and .2 each for the thick and thin spacers. Resolution of my scale is .1g so those may not be exact. Nice parts.

  • IceMupppet / about 13 years ago / 1

    These are incredible for all my projects! Please keep them in stock!

Customer Reviews

4 out of 5

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Exactly what we needed

A recent hackathon had us using a servo to twist a plate with a load on top and we wanted to take the weight off the servo. These proved to be perfect. They don't spin freely, but have a bit of resistance to them. That said, they are definitely better than just trying to rub two smooth surfaces together.