I needed one of those micro threading bars one time until I saw the price. I made one for cutting acme 10 threads. I turned an offset on a piece of drill rod but left a "disc" on the outer end , then ground it to the acme thread form and hardened it. That little boring bar has cut several internal acme threaded parts for me. It is in one of my threads on here but I have trouble finding things on here. I f you grind the tool accurately, you can get a perfect fit with no back lash.