Hello.

Bought these superb bits about 12 years ago; as "aviation" drill bits. Cannot find them now. Am I looking now at the wrong name ?

Could they be these? https://www.cnccookbook.com/split-point-drill-bit/

36 minutes ago, Externet said:

Bought these superb bits about 12 years ago; as "aviation" drill bits. Cannot find them now. Am I looking now at the wrong name ?

Are they all of the same length? Long bits may be referred to as "aircraft" drill bits.

(It is hard to determine anything special about the tip geometry from the photos.)

Edited November 1Nov 1 by Ghideon
tip geometry note

It looks like these are for a specific type of 'chuckless' drilling machine - normal cutting tips but how they are mounted is unusual. As a WAG I'd say for a production line drilling machine.

4 hours ago, StringJunky said:

Could they be these? https://www.cnccookbook.com/split-point-drill-bit/

Those are just different methods of sharpening and can be applied to any bit

4 hours ago, Externet said:

these superb bits

What’s superb about them and what do you use them for? Perhaps you should focus more on the type of metal used to produce them and sharpening geometry as more important factors

They held its sharpness for a decade cutting into many steels and other metals, and I bought them re-sharpened !.

Some are double diameter, varied lengths. Seems I just found these are 'Boeing' aviation drill bits, meant for production as Ken suggests above.

---> https://www.aircrafttoolsurplus.com/categories/Drill-Bits/

Now in the drill bit subject; does anyone have experience re-sharpening 'widia' tipped (for masonry) drill bits to work on any metal, ceramics, glass, anything ? What is the new angle/shape to be ?

130 degrees

21 hours ago, Ken Fabian said:

It looks like these are for a specific type of 'chuckless' drilling machine - normal cutting tips but how they are mounted is unusual. As a WAG I'd say for a production line drilling machine.

Yes. Look like for drill press chucks. What I've always wondered is if there is actually a masonry bit that will handle repeated use on early 20th century concrete. They clearly used a different formula, that stuff is like neutronium trying to get a hole in it (say, anchoring a new wall to an old foundation). I've thrown away several ruined bits, dealing with that stuff. And I'm talking carbide. I think some of that old concrete requires diamond bits. So, serious $$$.

13 minutes ago, TheVat said:

Yes. Look like for drill press chucks. What I've always wondered is if there is actually a masonry bit that will handle repeated use on early 20th century concrete. They clearly used a different formula, that stuff is like neutronium trying to get a hole in it (say, anchoring a new wall to an old foundation). I've thrown away several ruined bits, dealing with that stuff. And I'm talking carbide. I think some of that old concrete requires diamond bits. So, serious $$$.

Are you using an SDS rotary hammer drill? Do the drill bits have 4 cutters?

Edited November 2Nov 2 by StringJunky

10 minutes ago, StringJunky said:

Are you using an SDS drill?

I was (I borrow one). It works fine on most modern concrete. But this stuff I mentioned dates to around 1905-1920. I've actually thought of consulting a geologist who lives a few blocks up the street, near a tech school campus. Stuff is like granite. Admittedly the SDS drill I borrow is kind of cheap, so an upgrade might also help. (the neighbor who loans it out is kind of amusing - he bought the drill, used it once, and now is saying, "please borrow this! It will never get used unless people borrow it." )

1 minute ago, TheVat said:

I was (I borrow one). It works fine on most modern concrete. But this stuff I mentioned dates to around 1905-1920. I've actually thought of consulting a geologist who lives a few blocks up the street, near a tech school campus. Stuff is like granite. Admittedly the SDS drill I borrow is kind of cheap, so an upgrade might also help. (the neighbor who loans it out is kind of amusing - he bought the drill, used it once, and now is saying, "please borrow this! It will never get used unless people borrow it." )

A 4-cutter bit should help as well. and 2-4J of punching power from the drill.

2 hours ago, StringJunky said:

A 4-cutter bit should help as well. and 2-4J of punching power from the drill.

Thanks, yes 4-cutter and 4 flutes seems to be best. I have another project upcoming which will likely need a power chisel for demolition so maybe will just get a rotary hammer - will be overkill for drilling (10 joules per impact), but that's what's recommended for demolition with a chisel bit. None of it has rebar, but there are some granitic aggregates which seem to call for the 4-cutter.

The original use may have required a precise length/depth, thus the mounting 'knobs', that look like they would use grub screws to hold in place. And selling them on rather than sharpening for re-use would make sense. As pointed out in other comments the sharpening angles can be changed. The alloys used cannot; if a production drill in a demanding application then likely higher than usual quality alloy would explain their durability. Making them to replace when blunted (sold on after resharpening, not re-used) would make sense if length has to be precise.

I am imagining a quite large regular chuck would be needed to hold them.

Edited November 3Nov 3 by Ken Fabian

Thanks. Found several sources for the bits now using 'Boeing' as search term. Solved.-

Ken : It is actually a small chuck :