broken off valve stems

[bloke]

Most of you don't need to know about this, because you either have vintage instruments with much sturdier valve stems, or new instruments with sturdier valve stems - rather than the cheap student instruments whereby the narrow 4 mm threads on the stems actually hold in the plastic valve guides. Also, almost none of you are clumsy cannabis-stupored oafs, who beat your valve stems against door frames when you go through doorways...but here goes:

You're going to need a really strong (good steel) and sharp-bladed screwdriver that's a little bit narrower bladed than a 1/8 of an inch - perhaps a 3/32" or 2.8mm blade width. Position the blade across the center of the broken off stem threads, set the piston on some soft wood vertically, and pound a slot into the broken off stem threads. Once it looks as though you've got something that you might be able to use - as far as a slot is concerned see if you can simply unscrew the broken off threads from the piston. That sure is a lot less trouble than using it left-handed drill bit and an easy out. If it is stubborn about turning, put some Blaster penetrating oil on those threads and heat them with your torch until the Blaster bubbles real good, and then try it again.

Sometimes, you don't even have to do any of this mess and you can just take the corner of a screwdriver, mess around with the broken off stems, and they begin turning right away.

So far this summer, I haven't used any left-handed thread drill bits or easy outs, and you probably can guess that I've extracted quite a few broken off valve stems, particularly from instruments of my least favorite brand.

Good luck, and happy thread extracting.