I haven't seen this anywhere before, here is a mod to switch between wah and volume modes on a crybaby using a 3pdt switch. The first thing to check is whether the 3pdt has a long enough bush to be switched by your mechanism. The input of the wah cicuit is still connected so if your pedal sucked tone in bypass before it will probably be worse. This mod can be done without touching the pcb - it's all based around the pot and the switch.
to usual place in circuit (a .22u cap)
^
|
|
| o----output jack
| /
\----o
/ o----ground
\
/
\ o----to usual place in circuit (other .22u cap)
/ /
\<---o
/ o----output jack
\
/
\ o----ground
/ /
-----o
o----input jack/input to cicuit
(hope the ascii-matic isn't too confusing)
In Geofex.com there is a more simple way to do this, just usind a SPST.
here ya go
www.geocities.com/austenfantanio/wahtutorial.htm
i did this once, and guess what? the volume thingy works backwards!!!! :P
so heel down is max volume and toe down is min volume.
In the top scheme the sweep is the right way round but you may get some tone sucking. I figure anyone who wants to have either a wah or a passive volume always in their signal chain is going to lose tone anway (or know how to deal with it).
of course you could always build my wah in a box thing that uses a stanadard volume pedal as your wah pedal controller