do "they" make?

Thread rolling heads

Most do, usually tapered side is the side with the letters/numbers on.

Motorcycle frame makers used to use treacle, the dark industrial black stuff for doing this so the braze was restricted to the tube and lug area. a lot of early lugs were wrap rounds.

Sorry ??

Buy a genuine cast alloy Lennox frame, These are 302% better than any others I have seen or used. Can be air dropped on Bosnia and not break the blade.

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

Over here in Canada we call it "White Out", the type correction fluid. Works like a charm and does exactly what you want it to do. Mike in BC

At ~ 4mm diameter long solid carbide drills are hugely expensive, perhaps £15 for a 15x diameter long one. Short solid carbide drills cost about £1 (or 20p if you get them cheap). But the only bit that wears is the tip, and the bit that usually snaps is the shaft.

So make the long shaft from a decent tool steel which won't snap (tool steel as in screwdriver, not as in lathe cutting tool) and put a replaceable solid carbide tip on the end.

btw, if anyone knows of a ~ 1/8", 3.5 mm or so long carbide or carbide tipped drill going "cheep" ... I need to drill and ream a 55 mm deep 4 mm dia hole in Inconel X-750. Bought a long solid carbide 4 mm reamer at a show for a quid :), but I need a suitable drill.

Could you perhaps grind a masonry drill bit to do a one off ?

Spark erode?

Wickes sell what they call a Universal drill bit. It's carbide tipped, like a masonry bit, but with a zero rake cutting grind rather than the extremely negative rake of masonry bits. The flutes are deeper as well. They are claimed to be good for wood, steel and concrete.

You may have to experiment with the tip grind and you will have to use a lot of pressure to avoid work hardening, but you may do surprisingly well with these bits.

Mark Rand RTFM