=Introduction= A caster is an undriven wheel that is designed to be attached to the bottom of a larger object (the “vehicle”) to enable that object to be moved.
Casters are used in numerous applications, including shopping carts, office chairs, hospital beds, and material handling equipment. High capacity, heavy duty casters are used in many industrial applications, such as platform trucks, carts, assemblies, and tow lines in plants.
Casters may be fixed to roll along a straight line path, or mounted on a pivot or pintle such that the wheel will automatically align itself to the direction of travel.
=Challenges= Determining the best use of space is a process, not an end result. This is especially true when space is at a premium. Furniture and equipment are easier to move when they have wheels. But after you’ve moved them, they should be as stable as possible. So the casters should be easy to lock and unlock with a foot or a hand.
=Approaches=
Rigid casters
Swivel casters
Subcomponent count and 3D printability of existing caster designs were surveyed. Eleven revisions of test caster were designed, printed, and destructively tested to arrive at a working locking mechanism and feature construction given the constraints imposed by the FDM 3D printing process. Initial designs used 608 roller skate bearings. Later designs increased the number of axes with a preloaded bearing and decreased subcomponent count and cost by integrating printed bearing races into existing printed components.
Current components:
* 6mm stainless steel balls * Stainless M8x130 bolt, nut * 2x printed M8 thrust bearings * Printed flexible roller (1 hour) * Printed hub (1.5 hours) * Printed retaining ring (0.5 hours) * Printed locking lever (0.4 hours)
Interoperability
Vitamins
[https://www.surpluscenter.com/New-Arrivals/5-X-2-Swivel-Plate-Caster-w-Brake-WC6650-01-PAL-TLB-1-5780-SB.axd Casters for 3 inch frame]
Alternatives
*Children's bicycle wheels Modify a standard fork (actually 2) from a child's bicycle Weight capacity is still a concern *Furniture casters Available in heavy-duty 8“+ (20cm), 600+ lb (270 kg) varieties May need some sort of shock absorption for Wheelchairs **Can they handle the shear shock of running in to obstacles (curbs, potholes, rocks, steep ramps, etc.)
=References= * [https://en.wikipedia.org/wiki/Caster Wikipedia: Caster] * [https://www.thingiverse.com/thing:2680517 Sehome Swerve Drive 2] * [https://www.thingiverse.com/thing:31194 Simple Furniture Caster M8-M4] * [https://www.thingiverse.com/thing:2789451 Print-in-place caster wheel] * [https://grabcad.com/library/3-in-rubber-light-duty-swivel-caster-with-brake-harbor-freight-tools-61855-1 3 in. Rubber Light Duty Swivel Caster with Brake Harbor Freight Tools 61855]