For drilling brick or stone, these are the bits I use, often called diamond tipped bits. Do they have anything to do with diamonds?
Well, they’re probably actually tipped with little diamonds. Industrial diamond isn’t very expensive, and it’s the hardest abrasive available, so it’s used for all sorts of tools. Diamond cutting tools are especially good for masonry.
Yes, small diamonds are embedded or coated on to aid in cutting through very hard materials.
Yes, diamond tipped drill bits really do have itty-bitty diamonds on them. Look closely at one. See the teeny-weeny black gritty bits? Those are real diamonds. They’re industrial grade diamonds, which don’t look like the gem quality ones, but they’re still diamonds and still hard.
There also diamond grit sanders.
(Standard alumina oxide sandpaper could be said to be “ruby” or “sapphire” grit - again, it’s the same stuff, but industrial rather than gem quality.)
While we’re at it, carbide tools are made of silicon carbide, a material very similar to diamond (basically, diamond with half the carbon atoms replaced by silicon). It’s not quite as hard as diamond, but it’s still pretty hard, and much cheaper and easier to make tools out of.
You folks are fantastic with all this information. Thanks.
And when drilling masonry it is more useful to use a hammer drill than to have a diamond tipped drill. If diamond tipped drills are expensive then the money should be invested in the drill for any serious work.
I don’t think so.
Most drills are actually tipped with Tungsten Carbide. Silicon Carbide is much too brittle, and can’t be brazed like WC can.
I stand corrected.
So, basically, a diamond-tipped drill bit is a diamond-tipped drill bit.
That’s all you took away from this?
SO how do they secure the diamonds to the tip? Some kind of diamond glue? Wouldn’t it need to be just as hard?
Usually, the diamonds are embedded in a metal matrix. The metal wears away, exposing the diamonds. I’m not sure how they actually make the diamond-metal matrix (I don’t know if the diamonds and powered metal are applied to the drill as a paste, and then baked on, for example), and I’m sure that many process are trade secrets.
Note that while the drill bits are actually encrusted with diamonds, giving your wife a set for your anniversary does not produce the desired effect.
Various bonding techniques are used. Sodium silicate bonding is one technique. Cobalt-carbide combinations are often combined in powdered form (sintering), and then bonded to the drill bit. Sometimes diamond dust is bonded using conventional high temperature adhesives, and the drill bits must be kept cool during drilling operations.
I also recommend against diamond tipped tools as anniversary presents for your wife. Gifts to me of that kind are appreciated though.
I believe that there is a sintering process whereby a mixture of diamond and a metal is fused onto a blank. There was an earlier process (that my father helped develop in the US, see below) of electroplating onto the blank. Basically, you surrounded the blank drill or disk with a basket of diamond dust, immersed the whole into a solution of nickel sulfate, put one electrode on a hunk of nickel and the other on the drills or disk and turned on the current. Obviously, there are a lot of details I’ve omitted (one thing I do recall is that you needed three times the current density needed for ordinary nickel plating because the diamonds interfered with the plating. Anyway, you did this for a while (a day or so, IIRC) and, voila, the blank was covered with an incrustation of a diamond/nickel matrix. The same process was used later for Revlon’s “diamond coated nail files” but I believe the percentage of diamond was low and some other grit was used mainly.
My father was working for a company that made dental equipment (picks, mirrors, that sort of thing) in the late 30s. Diamond dental drills all came from Germany. With war imminent, it looked as though the supply would be cut off–as indeed it was–and the owner of the company decided they could make a fortune if they could work out a process–he was right. At any rate, my father was one of the people who developed this electroplating process. They kept it as an industrial secret–no patent–and later branched out into industrial tools, grinding wheels and “core drills”, in which the blank was punched out after the shell was guilt. Corning Glass bought zillions of them.
Incidentally, for esthetic reasons, they used white diamond dust for the dental drills. Also for Revlon, I think. White dust may have cost more than black, but there aren’t any uses for it in jewelry, so it probably wasn’t that much more.
I think white diamond dust is a byproduct of gem production (when you grind diamonds you use diamond dust and wind up with even more diamond dust) so it may not be that expensive, though probably more than the darker varieties.
What I still don’t understand is this: If the material they use for attaching the dust is so strong, why not just use that for the drill bit? Why bother with the diamond dust at all? Is it just marketing?
'Cuz it’s not as abrasive. Just a strong bond-er. (That’d be the technical term.)
It’s like asking why, if sandpaper is grit glued to paper, they don’t just sell you glue-covered paper. It’s the grit that does the job. Likewise for diamond-tipped bits - it’s the diamond grit that does the job, not the stuff holding the grit on no matter how strong it is.