I have a heap of small holes to tap shortly and I want them to be firstly straight, and secondly I dont want too many (nil!) broken taps. I therefore needed a piloted tap driver!
Almost all my holes are 4 BA so Ive built this around that particular size. I will make a few more in common sizes though...
The unit itself is quite simple BUT... I had my first attempt at knurling, and while not perfect, Im pretty impressed with the result...
![](http://i293.photobucket.com/albums/mm54/artieonedge/29032010159.jpg)
![](http://i293.photobucket.com/albums/mm54/artieonedge/29032010161.jpg)
I might just go and knurl something else.....
![:ddb:](https://madmodder.net/Smileys/default/dancenana.gif)
P.s. that a 4 BA die next to it for reference... centre shaft is 12mm.