I have a lot of frozen countersunk T10H security pin Torx head 6-32 screws to remove from cast aluminum weatherproof enclosures. I have tried tapping, torqueing in both directions, penetrating oil, heat gun and ice/freeze mist. Tried to use a drill press and clamping the enclosure in a vise, but even then, the security pin makes the drill bit "walk" off the very hard screw. Someone told me there is some kind of electrical device used my machine shops to remove screws from engine blocks, etc., by "burning" the screw out. Will this work on screws as small as 6-32? If so, what is the device called, so I may intelligently call around to machine shops to see if they possess one of these devices? Any other ideas? I have snapped screws off and also snapped off about 5 T10H tool bits. I there any special penetrating oil for stainless steel to aluminum tapped holes?
You are looking for Electrical Discharge Machining (EDM) and some versions should be able to work at the size you need.
The simplest solution is using a screw extraction kit. Since you know the size and threading, once you drill and exact the security screws, you simply replace them with the appropriate sized non security screws. Or you know, use new security screws if you need that extra bit of annoyance. It's not like security bits are hard to find, you broke 5.
As a preventative method, apply anti seize oil/grease/tape to the new screws.
I have used a small battery powered Dremel with a abrasive cut off disc to cut a screwdriver slot through the middle of head. Start off by making the smallest slot you can. You can always make it bigger and get a larger blade screwdriver. Just be careful how deep you go as you might break off part of head off while turning and screw will remain. Old reliable slotted screw heads.😉