I am considering making an anti backlash nut for my HF micro mill. I would like to use the stock leadscrews until they are worn out, then i will look at ballscrews.
The current nuts on there are some type of iron, which i would expect has a lot of friction.
Using the method as shown here:
http://www.embeddedtronics.com/acmetap.html
I would liek to make my own tap and produce a type of anti backlash nut. But what is the ideal material for this? Is it delrin, or is delrin too weak? I have never used it before

I used Delrin on my Z axis, and it has worked great. And it has traveled miles up and down with no wear that i have noticed.

Did you make the nut yourself?
Even this amchine is small as far as mills go, its a brute for its size. With mostly cast iron, so I was just afraid that the delrin would not be strong enough. It will have to be strong enough to withstand the resistance put in place by the gibs. I dont think its a lot, i dont go ultra tight on the givs, i can move the table by hand.

Brass or Bronze... is probably best of the bunch.

Why brass or bronze?
That would be an easy thing then, since school has tons of brass stock.

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.