Greetings and Happy New Year,
Does anyone know what sizes and pitches are used in Vac and P51 caps?

Happy New Year to you.

The clip retaining screw has 10-32 threads.

The jewels are 3-56 (most common) and 5-44.

Todd

Thanks Todd. And the Cap to Barrel threads???

Gerry

Gerry,

Non-standard.

The cap threads on a VAC are quad-lead. I THINK they are 36 tpi. The ODs are what Parker chose them to be.

Todd

Close, but not quite. The threads are tripple start, 36 TPI. Parker made many things with non-standard sizes. For instance, jewels for some of the early vacs are 32 TIP, but the diameter is neither #10 nor #12.

There are also two sizes of jewel threads in the clip screws. The Vacumatic and Vac fill 51s are the same size, the later aero 51 jewel threads are the 3-56. Which is a pain if you shear off the jewel on a vac 51, because all of the jewels you find today are for aero 51s, so you have to change the clip screw too.

Thank y'all so much. Now I know what to add to my ever growing tap collection...

Triple start taps can be bought ?
I realize that a lathe operator using single point cutting can do this ( not ME though ) ... by indexing the lathe for the second and third starts... but I can't visualize a three start tap ..... I am hoping they make them because it would open up the possibility of making some mesquite caps...