Below are some photos of the design and the test rig. The outer body of the brass is .250". The hole drilled in the brass is .187. The hole for the stem is .109. The valve OD is .250 with a .125 step to the .109 diameter. I used a 90 degree countersink to cut the taper in the brass and a tool bit ground at 45 degrees and aligned to the chuck with a 45 degree block to cut the angle on the valve. I used a Starrett pin vice to grab the end of the valve to lap it in. To test it I put a piece of polyurethane tubing, 1/4" ID 3/8" OD, over the valve body then a piece of 1/2" OD 3/8" ID polyurethane tubing over that and secured it with a breeze clamp. I then hooked it to my regulator set at 40 psi. The bubbles in the photo were taken at 20 psi. At 40 psi it is a constant stream of air coming out around the stem.
I was using a lapping compound made from 220 grit carbide powder and oil, than 600 grit carbide powder and oil, then the Tormek polishing compound. Under the microscope there were lots of scored lines on the steel and the brass. I tried re-cutting the brass and polishing the steel then using just the Tormek polishing compound and that did no better. What am I doing wrong?
Roger L