Mobile Cabinet - Caster Location

[Bugsysiegals]

I'm building a mobile cabinet and want to place the casters in a location which best prevents sag without adding requiring any additional reinforcement material.

In the images below, I've placed the casters 9" from cabinet edges to caster center which leaves ~15" from caster center to cabinet center per side (30" span). My thoughts are that this limits the center span to minimize sag leaving a small overhang which I suspect will not sag at all and leaves the casters far enough apart to maintain stability ... does this look good or is there some other magical distance formula for building I should use?

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[ear3]

Not an expert in these issues, but that's basically how I would do it.  I assume there is enough clearance for engaging the locking mechanism, and that you won't need a spacer block?

 

[Bugsysiegals]

Yep there’s enough clearance. I can actually push the caster in just a bit deeper if I want and I’m going to use tee nuts on the inside so I don’t have to worry about clearance on the bottom drawer box.