what tap would he need? M5 x 0.5 Metric HSS Right Hand Thread Tap?

regardless, my suggestion is, if you use a tap, use a proper tap wrench with it. not locking pliers to turn it. I have something like this Vermont American 21916 T-Handle Tap Wrench 0 through 1/4 Inch

I have used left hand drill bits like these. you might want more than one in case you break one or it gets dull Century Drill and Tool 74108 Left Hand Stub Drill Bit, 1/8-inch

here are some others I've used Irwin Tools 30508 1/8-Inch Cobalt 135-Degree, Left Handed-Mechanics Length, Pack of 6

for normal drill bits I like these DEWALT DW1361 Titanium Pilot Point Drill Bit Set, 21-Piece

for screw extractors, I didn't have luck with the easy-out type. they do work for some ppl but I settled on straight fluted extractors like this Williams EX-21A 1/8-Inch Fluted Screw Extractor

my project was on a slightly larger bolt whose head I broke off in my Subaru. drilled a hole in the bolt, then proceeded to break a hardened steel easy out in the bolt probably cuz I used locking pliers to turn it not a proper tap wrench, so then I had to drill into that hardened steel tool, inside the bolt. in order to get a proper hole for the extractor. so don't be like me, don't break a hardened steel tool in the hole that you drill!

take your time, be patient, don't rush, use the right tools, where eye protection, don't give up, my project spanned several weeks, but I got it because I made sure the hole was deep enough & the correct diameter for the extraction tool







sometimes a left hand bit is all you need