Drill a hole in HSS?

I'd do it with my EDM. Piece of cake. There may be another way, but don't know of it.

Karl

Guy Lautard claims that a "Cole Drill" will do it. Ken.

Brand 'spankin new carbide drill, very low speed (60 rpm) very high pressure.

Would coolant help here? I've heard coolant sometimes causes temperature variations in Carbide bits used this way which cause microfractures or even chipping of the tool face...

Is that an edm that you made yourself or the commercial variety? (Thinking about building one of those Home Shop Machinist versions one day...)

Thanks, Charles Morrill

Charles,

If it is a 'one off' I'd use carborundum dust or preferably diamond slurry. 'Valve grinding paste' from a car accessories shop will do.

Make a 4mm copper 'drill' - just a flat ended piece of rod. Mount it in the drillpress, and build up a dam where you want the hole using plasticene or putty. Fill the dam with a mixture of oil and the abrasive, and bring the 'drill' down at about 100 rpm keeping gentle pressure on the work. Every now and then raise the drill and lower it to keep fresh abrasive at the cutting face.

You'll be surprised how quickly it works. Same technique can be used to drill glass.

AWEM

Fascinating, many thanks to you and everyone. This one I have to try...

Charles Morrill

I'd be interested to know if Andrew has had success with this method in HSS. I've used it often, in glass and ceramic, where it works reasonably well. I once drilled the bottoms of 60 vases that were being converted into table lamps and, by the end, I was getting through the ceramic in about 5 minutes. You get some taper from top to bottom in the hole, but you do get a hole. I use silicon carbide grit, 90-grit when I can, 120-grit when the 90-grit tears up the edges of the hole. I've also used 200-grit but it's very slow.

However, I find that copper tube is not concentric enough to give me a good hole. I turn and drill a piece of brass rod for the job since my early experiments with copper tube. I also file some shallow notches in the end of the "tube" to help hold the grit, with the coarser grades.

It's very, very slow in metal, in my experience. I used it to drill through a HSS power-hacksaw blade, Sandvik, of unknown grade. It took me about an hour to get through a 1/8" blade. Maybe there's a trick I'm not aware of but I tried fast and slow, light pressure and heavy pressure.

The easy way to do this job is to have the HSS annealed and then drill it. You probably can get through it OK with a HSS drill bit, but I haven't tried it. I have turned annealed HSS, and, while it's still a b*tch to machine, it does machine. I did that with a HSS bit.

You cannot just heat HSS with a torch to anneal it. Check Machinery's Handbook or another good source for annealing info, if you go that route. Re-hardening it is not for the ill-equipped or the faint of heart, either.

I'd prefer to leave it hard and find a way, given a choice. It's such a simple EDM job that you may find a mold shop in your area that will do it for you cheaply.

-- Ed Huntress

Greetings Ed, I've done the tubular abrasive thing to drill through stones and HSS. What worked best for me when drilling through parting tools was to put the abrasive ( Clover compound) on the part and bringing the tube down hard on the part with the spindle off to press the abrasive into the face of the tube. Charging the tube with abrasive this way worked pretty well. The tube can be spun fairly fast without flinging all the abrasive off. With stones I used a drilling machine that spun sorta slow and automatically lifted the drill at regular intervals to allow fresh abrasive slurry to enter the hole. It was real slow and the best thing was to set it and check back later. Much later. Eric

Well, that sounds like something worth trying. I'll remember that the next time I have occassion to use the method. Thanks.

I've never tried it with stone. Maybe I'll try it with some local stones I've tumbled.

It's a Southbend/Hansvedt 150B EDM that I restored, at great expense!!

Use a cement bit... You can drill through a ball bearing with one.... Keep it sharp...

I've used a spearpoint glass cutting drill bit for a couple holes, before it wore out. The kind available at most hardware stores. Took about 10 min. to get through the first hole in a 3/16" planer blade, longer for the second.

Ken Grunke

What I used was a solid carbide drill. I bought mine at MSCdirect.com

The drill and M2 or M42 - never found out - turned red hot - and so did the work. Then the hole was drilled cleanly. I extracted the drill and allowed the work and drill to air dry. The drill wasn't harmed. The hole was there. I was making a form tool.

Martin

It must have been to late :-)

The metal I drilled was either M2 or M42. When I drilled it with the solid carbide drill, in a drill press, the work and the drill both glowed red. Both were air cooled. (not dry...) Seemed to be the way to go. Martin