Hello, I'm building a CNC Router that will use a Dremel tool.

My problem is that I need to use a 13/64 (aprox 5mm) drill bit.
It's two big for the shaft.

Does anyone know where I can find a solution ? maybe a special
bit with a smaller shaft made for the dremel ?

I could get one machined down, but is there a better solution ?

Thanks
-Areal