[ Ref. Harold Ulmer in 220813 MMD ]

> Before I attempt making one, does anyone have a spare "wooden button"
> from a pot metal Wurlitzer 4-in-1 unit valve? I found in rebuilding
> my twelve 4-in-1 units that one unit was missing a button completely.
>
> If you don't have a single button but have a complete, unrestored
> 4-in-1 unit I would be happy with that as well. Let me know if anyone
> has a single button or a 4-in-1 unit, and the cost if available.

I have made replacement buttons. They are not difficult to do if one
has a small lathe with collets. Due to grain alignment, the edges of
the buttons tend to chip easily.

The center core is held in with shellac, not glue. This way one
can adjust the travel depth of the valve. I made a little jig for
re-leathering the seating edge.

20 years ago I looked into replicating Wurlitzer 4-in-1 valves in
different materials and/or 3D-printing one. The metal used in the
originals is of low quality. These castings have a tendency to warp.
The gasketed surfaces need to be polished to an almost mirror-like
finish. This is also true of the valve seats. Vacuum is not forgiving
of the smallest of leaks.

Cast resin in a silicon rubber mold might be a viable option. At one
point I looked into injection molding. I no longer have access to that
technology.

The tricky part would be getting base plates stamped. Minimum orders
for that sort of thing are in the 10s of thousand of units. Die
casting is also similarly prohibitive.

Mike Kitner attempted to replicate these valves in aluminum using
sand casting. The results (most of which I tossed out) were less than
satisfactory.

I did make CAD models of the unit assembly parts. Undercuts prevent
using additive 3D printing. There are newer resin-cured printers which
could be an option. Printing in metal is still a bit out of reach.

Bill Black once had a nice article on restoring these units using
blotter paper. I think it is no longer online. One can get new blotter
paper from office supply stores such as Staples. A lot of executive
desks still have the blotter paper well.

His method was to ink the valve then use that to print the image on the
gasket then cut it out with a hobby knife. I used my CAD models to print
directly on the blotter paper and cut by hand. This can also be done
with laser cutting.

(I may have an extra home made 'wooden button'; contact me off list if
interested. It might be a bit expensive as these individual parts such
as a single wooden button can cost around 100 USD each.)

Julie Porter
Martinez, California