???? Got a few of them. Special application? Made by Guhring but the part numbers etched in give me nothing on google.
Seen them with 4 flutes and were called core drills, they were mainly used for drilling rough casting bores etc.
Three flute drill, used for drilling hard stuff, also useful for opening out existing holes without them going a funny shape
I will buy them if you are selling? Great on sheet metal and plastics. Edit: And keeping holes round as ^^^^
Thanks. I think they’re all 7.5mm or 8.5mm so I can’t see myself reaching for them too often. Not sure how many I have, if more than 5 I might sell the rest. I’ll have to try them out on a few bits.
I used to grind a steeper angle for drilling stainless and 8.5 is drill size for tapping 10mm x1.5 so a useful drill to have in your box.