Diamond Drill?

[Will]

Anyone know why you can't buy diamond drills - I have a diamond saw but the hardest drill I have is HSS Cobolt?

[Dave Osborne]

Because diamonds "grind" rather than "chisel".

For drilling stone, there would be no advantage to making a diamond drill over a TCT drill and it would be a lot more expensive.

For drilling wood or steel, the grinding action of a diamond drill would be inefficient compared with a tool that cuts ("chisels"). Now, if you could make a solid diamond tip for a drill and put a cutting edge on it, that would be awesome (assuming it wasn't too brittle to be of any use).

[The Medway Handyman]

You can buy diamond core drills, which, as Dave says, grind their way through. Beneficial for large holes in stone but that's about all.

[The Natural Philosopher]

eh? I have diamond drills for tiles and stone..brilliant.

[Dave Osborne]

Good point, well made. Although, just to be clear, I was rather thinking of a solid drill rather than a core drill (which I was think of as a saw, rather than a drill). :-)

[The Medway Handyman]

Which it is if you think about it.

We have a local diamond drilling firm called Rajinda & Sons. The slogan on their vans says "You've tried the cowboys, now try the Indians" :-)

[Dave Osborne]

[Dave]

There are 3 drills harder than that, but you will have a hell a lot of trouble tracking them down. Even Dormer do do not list them.

C1150 come next with D200 following Solid tungsten carbide was used for drilling carbon fibre.

Dave

[Tabby]

It would be too brittle. The way to make practical hard material bits is to embed little pieces of the stuff in a softer matrix. That gives he hard cutting material plus the slight flex of the softer stuff, thus eliminating the brittleness.

Diamond drills do exist, but for wood they're just not necessary. A properly designed bit will do a fine job - unfortunately many are still struggling along with ill suited bits like twist drills.

NT

[Dave Osborne]

Good point. You can buy solid carbide drills for drilling printed circuit boards.

[Spamlet]

they are full of glass these days...

S

[Dave Osborne]

Yes, the common professional quality board is FR-4, which is made of layers of glass fibre mat impregnated with epoxy resin.

thing about drilling circuit boards is that you need the hole to be perfect every time. Commercially, boards are drilled clamped between sacrificial substrates so that there is no surface spalling on entry or exit. Also, they drill at very high speed, so as soon as the sharpness of the drill goes off, it tends to burn its way through. PCB drills have a limited life because of the glass content in the PCB, but solid carbide drills lasts much longer than HSS.