Brass and bronze are classic low friction material for nuts... And they are not as subject to temperature like Delrin. They won't marr the screw and will last a good long while.
I've got a Micro Mill as well and have been thinking along the same lines.. I did make a set of 1/2"-10 acme screws and Delrin nuts for the Micro a while back. But they were no more efficent than the stock screws and nuts. So I switched back to the stock screws. Even under CNC conversion the Stock screws provided the same rapids and back lash measurements. (I did switch the Z axis to use 3/8"-16 stainless screws and a brass nut. and thatwas much better than the stock Z setup.) I'll be going back to this setup when I re-CNC the machine in another month or two.
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Nathan |