Saw bench casters

[Frank S]

A couple of thoughts so for anyone including myself contemplating adding any wheel system to a machine stand for moving around their shops.
As a general rule we want or need our wheel systems confined within the square of the footprint of the machines. for reasons of space or to not having them create a tripping hazard when working around the machines.
By having the castors inside this foot print when deployed the square of the contact area to the floor becomes less which can create instability when being moved.
Larger diameter casters have a lower rolling resistance due to the increased length of the included angle of caster axis or castor offset. A 2 inch caster might have only an inch or less of circular contact movement when changing directions resulting in the footprint reduction while a 4 inch caster could have as much as a 3 inch change making the foot print even less under the machine this in turn can change the center go gravity significantly making the machine or other item such as a tall tool box or narrow work bench especially a lathe easier to tip
Next the larger the wheels the more emphasis or attention needs to be taken on the rotational lifting axis while that axis could be centered on the same axis of the castor for smaller wheels it should be offset for larger castors to reduce the overall lifting height. especially on things with an offset center of gravity such as a lathe or a press break the heavier side usually the back or the side away from the operator needs to be raised first or the lifting action should have an offset fulcrum point so more lifting power is exerted to the heavy side.
I hope my lengthy explanation can make some sense as it would be much easier for me to explain if I were to draw up a model but that takes quite a lot of time