We have all broken a tap or drill in a component that we were repairing or making, or had a stud or bolt break and finished up with a broken extractor that cannot be drilled or removed.
Methods to remove studs and bolts include heating or welding nuts to the stud or bolt; sometimes these work, but often do not.
Do not despair, forget all the advice given about fancy drill bits etc., see the website
http://www.sparkeroding.co.uk/ where the process is described and who have been doing this service since 1999.
The service is not cheap, but is less expensive than scrapping a valuable component or having a commercial vehicle off the road for several days.
Small items may be delivered to their premises for a cheaper service.
Spark eroding or electro-discharge machining is usually used with a very large machine with xyz axis, but with limited capacity for holding a component. Portable machines now exist which can be taken to the work piece and set up to remove the offending article. Such spark eroding machines have been used in ship's engine rooms, and inside other large manufacturing machines. These spark eroding machines can be used with electrodes as small as 0.025" up to 19mm, there is no upper limit as several "cuts" can be made until the tap etc falls apart.
Recent work includes studs on several ships including a Dutch ex-minesweeper, an oil rig supply ship, several industrial engines and broken taps and studs on commercial vehicle engines, numerous manufacturers and work for various M.O.D. contractors.
The process does not heat up the parent metal and usually removes the broken tap or drill without damage to the work piece, but removal of broken studs etc may damage the threads requiring fitting a wire insert or similar.
We have removed
broken head studs from MV
Lady of Man in Liverpool,
and a Dutch ex-minesweeper in Hull.,
and head studs for Deutz Engines,
a broken stud in a Beechcraft engine in Lincolnshire,
