Hexagon Milling Threaded Nuts – by Cadser

The top nut for my lubrication system required to be turned from brass bar stock. The end then needed to be threaded 3/8 x 32 TPI which is best done in the lathe whilst things are true. The spanned end needed a 10mm A/F hexagon putting on so that we can work it with a spanner. I do not have an attachment for the lathe to enable milling, so it has to be done in the vertical milling machine.

To do that i turned up a dolly, bored and threaded it to the 3/8 x 32 TPI. The start of the internal thread is releived by 1mm to allow a blind threaded item to be screwed right up to the shoulder on the part and the face of the dolly. This holds it nice and straight. The unmachined end of the top nut is held in the vice and enough torque added to make sure it does not turn during milling. When its finished the nut can be taken out with a spanner.

Set up ready for milling

Milling underway with an end mill running at about 1500rpm cutting left to right.

Finished milling and ready for de burring, i also need to move the lathe tool to centre height, but i do find parting off is better with the tool slightly low on centre.

I use one of these tapered reamers for deburring brass as it leaves a nice crisp edge and a better finish than a file which leaves too rough a finish .