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Tips/Techniques Drill/Grind small hole in very hard steel

Tips/Techniques
slow-poke

slow-poke

Ultra Member
A friend has asked me to drill a small hole about 3/16" diameter through some very hard steel that is 3/8" thick.

HSS is useless, Cobalt made a 0.01" dimple, solid carbide makes a little dust but not much more. I also tried some small Dremel style grinding and diamond tip tools, they make a tiny amount of dust but that's about it. Torch is not an option. Plenty of time but I need something that will work. Suggestions welcome.
 
slow-poke said:
A friend has asked me to drill a small hole about 3/16" diameter through some very hard steel that is 3/8" thick.

HSS is useless, Cobalt made a 0.01" dimple, solid carbide makes a little dust but not much more. I also tried some small Dremel style grinding and diamond tip tools, they make a tiny amount of dust but that's about it. Torch is not an option. Plenty of time but I need something that will work. Suggestions welcome.
Click to expand...

I found that one good trick is pressure. Quite contrary to instinct but it works!

There is a lot of reading to find the good stuff in this thread, but hang in there. I think what you need is there.

Post in thread 'Cutting High Strength Steel Forging' https://canadianhobbymetalworkers.com/threads/cutting-high-strength-steel-forging.10695/post-151194

Might also want to google Coles method of drilling.
 
Some friend. lol.

Mystery metal? I'm guessing that as if it was some needed alloy for design he would told you what was, right? If so ....my first thought is a design change - asking him to provide something than can drilled, and maybe so new cutters :). I found the graph below which is interesting - I'm surprised at how many steels are harder than M2. I don't recognize any so would guess they are rarities.

I'm surprised carbide wouldn't work, I've pecked away at hss taps with it and it worked (using a tiny endmill) - mid 60 rockwell tap has is pretty bloody hard. I've a home made EDM for tough stuff, but haven't used it once I found out how well carbide works (and try not break the dang things, since firing 10 24 years ago I haven't broken a one) It's a bit wild so not sure the tolerance it will hold, but we could try that. By the time you did all the running around it would be the better part of 1/2 a day so hope he's a good friend .... but I'd be up for giving it a go.



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Mcgyver said:
I found the graph below which is interesting - I'm surprised at how many steels are harder than M2. I don't recognize any so would guess they are rarities.
Click to expand...

Wow! Cool chart Mike!

Thank You!
 
mbond said:
A small hole will be much harder than a big one. Is this part attached to something, or can you put it into a machine?
Click to expand...
Unfortunately it's attached to a larger machine, so a hand drill will have to be used, and that really makes it tricky. Perhaps the carbide bit I tried is not suitable, I ordered another style, and will give it a try when it arrives.

I might try grinding a small carbide masonry bit, seems like some have been able to get through some RC 60 steel with the right grind. That should give me some sense of just how hard this stuff is.
 
slow-poke said:
Unfortunately it's attached to a larger machine, so a hand drill will have to be used, and that really makes it tricky. Perhaps the carbide bit I tried is not suitable, I ordered another style, and will give it a try when it arrives.

I might try grinding a small carbide masonry bit, seems like some have been able to get through some RC 60 steel with the right grind. That should give me some sense of just how hard this stuff is.
Click to expand...
I have seen this done with success.
 
slow-poke said:
No mag drill, I wonder what it costs to rent one?
Click to expand...

If I had to rent one I'd go to Home Depot. I know they have them.

But @David made a great point. At Vevor's price, buying instead of renting makes a LOT of sense!

FWIW, I usually buy tools when I do a job for someone else....... Especially if they are buying!
 
slow-poke said:
Hmmm. That looks promising. I just watched a video of a guy drilling through HSS and Cobalt bits with one. Does not appear to be super fragile. What do I need to know?
Click to expand...
The drill as you would expect, is very hard and brittle. A mag drill would be needed to apply high pressure and slow speed. And flooded with a good lubricant. Slow is the key point - this drill produces tiny chips (like an end mill) so it is very prone to chatter.
 
That's going to be hard. Unless you can change the problem around, it is likely to take a lot of patience as you abrade the hole. A diamond burr is probably the best tool, but it will be very slow
 
mbond said:
That's going to be hard. Unless you can change the problem around, it is likely to take a lot of patience as you abrade the hole. A diamond burr is probably the best tool, but it will be very slow
Click to expand...

My application and tool of choice was slightly different, but I found it surpringly fast. High pressure made all the difference. Of course that was in comparison to zero progress before that.

This makes three different places where pressure matters counterintuitively. Parting on the lathe, using carbide inserts, and drilling hard metals. I'd love to see some high-speed video of the drilling process.

It will be interesting to see how @slow-poke makes out.
 
slow-poke said:
Hmmm. That looks promising. I just watched a video of a guy drilling through HSS and Cobalt bits with one. Does not appear to be super fragile. What do I need to know?
Click to expand...

Another option is these new burrs from Drill Hog. They make a big deal about their new design.

drillhog.com

8 Pc Carbide Burr Set Drill Hog® Lifetime Warranty Free Bonus Items

Drill Hog® 8 Pc Carbide Rotary Burr SetIncludes:8 Tungsten Carbide Rotary Burrs1/4" Double Cut Ball Cutter3/8" Double Cut Ball Cutter1/4" x 5/8" Double Cut Cylinder Cutter3/8"x 3/4" Double Cut Cylinder Cutter1/2" x 1" Double Cut Cylinder Cutter3/8" x 3/4" Double Cut Cone Cutter3/8" x 3/4" Double...
drillhog.com drillhog.com

I tried to get a set while they were being promoted but I couldn't get my order processed and gave up.
 
Susquatch said:
Another option is these new burrs from Drill Hog. They make a big deal about their new design.

drillhog.com

8 Pc Carbide Burr Set Drill Hog® Lifetime Warranty Free Bonus Items

Drill Hog® 8 Pc Carbide Rotary Burr SetIncludes:8 Tungsten Carbide Rotary Burrs1/4" Double Cut Ball Cutter3/8" Double Cut Ball Cutter1/4" x 5/8" Double Cut Cylinder Cutter3/8"x 3/4" Double Cut Cylinder Cutter1/2" x 1" Double Cut Cylinder Cutter3/8" x 3/4" Double Cut Cone Cutter3/8" x 3/4" Double...
drillhog.com drillhog.com

I tried to get a set while they were being promoted but I couldn't get my order processed and gave up.
Click to expand...
U$140 still a lot better than U$300! I can never get over Drill Hog's pricing.
 
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