HSS / Carbide drill bits - telling apart?

If you have some known steel bits of similar size, the carbide ones are a great deal heavier. Also, they are darker gray.

Aluminum oxide might "skitter," but silicon carbide disks will dig in. I don't think they'll spark at all.

My 1st suggestion would be to check them with a magnet. I don't think carbide is magnetic

CarlBoyd

Tungsten carbide itself is not, but the binder usually is. Carbide binders usually consist of cobalt and/or nickel, both of which are ferromagnetic.

If you have a steel bit to compare it with (or a steel drill bit of comparable size), you'll notice that the attraction of the carbide to a magnet is much weaker than that of steel. But it can be hard to tell if you don't have a steel piece with which to compare it.

Use a known piece of HSS, like a lathe bit, and try scratching it with the cutter in question. carbide will scratch HSS easily.

For bigger sizes, I just tell by weight.

i

File test.

HSS drill shanks are soft enough to score with a file.

Carbide is not.

It would not grind well at all -- unless you had a diamond wheel.

If these are the kind with a color collar to mark the size just before the transition from the 1/8" shank to the bit, it is likely that this is for printed circuit board drilling -- and carbide is the only choice under those conditions. I used a HSS #70 bit once to drill about

50 holes in a G-10 (Glass-epoxy) PCB for mounting components and by the time I was done, the shape of the bit was closer to that of a needle, and the holes were lined with glass fibers. The heat had burned out the epoxy, leaving the fibers.

It was then that I put in an order for solid carbide bits, and neve regretted it.

I've picked up batches of the PCB drills at hamfests with the color colars. IIRC, the color indicates the last digit of the size, but I've never been truly sure.

Enjoy, DoN.

I was thinking of mentioning the weight/mass (juggling it in one hand), which I user as a quick guide in larger tools -- but these are

1/8" shanks and much smaller actual cutting parts -- not enough to really give a good feel for the mass -- especially lacking known HSS versions in the same format.

I think that you are right. It has been a long time since I tried to sharpen carbide on a standard stone. :-)

Enjoy, DoN.

Now Don - I know what G-10 is - but isn't it FR-4 ?

I think G-10 was banned or stopped being used due to flame issues. You can usually find good carbide drills for pcb drilling in the kits for Dremel machines. They normally have a plastic ring on them with the size or spec.

I used to route and drill pcb material on a small CNC prototype machine and drills of all types and spot as well as hole. Milling with 5 mill two flute, flush cutting endmills.

Still have some of the software (impedance calculations) and material selection.

Wonder if any of my former pcb vendors are still working. I was doing work with sample designs of CMOS and SiGe.

Mart> >> Needless to say no original packing. Sub-mm bits with 1/8 inch shanks. Other

I have several thousand of these drills, if anyone needs any sets

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Thanks all. AFAIAA the tips of masonry drill bits are always carbide. Tried an unused part of a needle file against such a piece of carbide and a known HSS drill bit and could not convince myself either way. Don't know what sort of grit, but rust brown (binder?) parting off disc in a Dremmel. Just cleaned up the surface of the carbide and slotted the HSS. So repeating with these unknown small bits , HSS

Not when I was doing it. :-)

Do you know when?

And in batches at hamfests -- for whatever reason. I suspect that they are "resharps" which are close to their minimum length. Sold in large lots by the houses which use them -- or perhaps the resharpening house.

Nice!

Runs on what OS and hardware?

Define "set" here. What range of sizes, in what step size? I would presume a max size of 1/8", and a minimum down where the skinny leads on diodes and TO-5 can transistors lived -- perhaps plus a bit to allow for through hole plating.

Enjoy, DoN.

Not exactly. I suspect it was during Viet Nam or NASA.

I believe it was in the 70's. By the early 80's I kept hearing FR-4.

I suspect the NEMA spec could be checked.

Looks like G10 is still in use! - catches on fire it keeps burning. FR4 self extinguishes.

Interesting. I know when dealing with PCB's that were in the tens of thousands in parts on a table - you don't use risky material.

I suspect - Mil banned them - e.g. NASA and Aircraft for certain.

Martin

Mart>> >>

My standard test for sub-mm bits with 1/8" shanks is to look at them crosseyed. If they snap, they're carbide.

They work OK in a small precision drillpress at high speed, as for drilling circuit boards.

The low-cost PCB houses have min hole sizes around 12 to 14 mils now, as for vias on surfacemount boards.

Ill dig em out and run sorta an inventory.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Thanks!

BTW -- did you check out the 6-jaw chuck jaws you have, and find whether any of them would be likely to fit my Burnard-Pratt 6-jaw -- especially outside jaws?

Again, thanks, DoN.