This type of valve can be made quite efficiently with just a small lathe and some files.
One of my favorite 3/8" impact wrenches bit the dust the other day. I hadn't used it in about two months and when I tried to turn the air flow valve, the dial knob broke completely off. It's cheap cast zinc alloy and not repairable.
Once I had it apart, I found that the metering valve had a crack in it. Which makes sense because the valve has been harder to turn of late than in previous years.
I tried to find a replacement, but the only importer of this wrench quit stocking parts years ago and besides, the market for angle head impacts dried up decades ago as well. Since it's one of my favorites I decided to make a new valve.
The dial was still intact and all I did was face off the broken end and drill and tap for a 5x1.5-mm machine screw. A few drops of red Loctite and the screw was permanently attaches to the dial.
The entire valve assembly looks Like this --
To make the metering valve I chucked up some round aluminum stock and slowly crept up on the diameter -- 0.473". Making such small parts in an imported HF Chinese 3in1 is a bit of a chore, but it does work.
a half hour later I had my roughed in part -- all drilled and tapped to receive the 5x1.5-mm machine screw I put in the dial.
A little more work with lathe and I had a new valve.
It was close enough to the original -- a rough piece, but it can easily be hand finished.
A few zips with the a flat bastard and a round file and I had my cam profile back to match the original.
I used red Loctite to permanently fix the valve to the machine screw on the knob so that the entire assembly can turn as one unit. A new "O" ring completed the job and after reassembly is worked like new. Much easier to adjust and regulate than before.
