How to drill hardened steel

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How to drill hardened steel

This topic has 23 replies, 16 voices, and was last updated 21 November 2016 at 20:15 by Men Ifr.

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11 November 2016 at 10:57 #265974
Men Ifr
Participant
@menifr84251
As above what do i need to do it I will use my mill as a drill press.

Will titanuim coated hss drill bits be sufficient?

Im guessing coolant will help…
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11 November 2016 at 10:57 #29651
Men Ifr
Participant
@menifr84251
11 November 2016 at 11:14 #265981
Douglas Johnston
Participant
@douglasjohnston98463
It depends just how hard the steel is but carbide drills are the best bet. The main problem with carbide drills is that they are quite brittle and need to be used with care.

Doug
11 November 2016 at 11:44 #265988
Dave plus / minus 40 thou
Participant
@daveplusminus40thou
You can use a masonry drill bit (with a carbide tip) at a push, sharpen the cutting angle and use coolant

Dave
11 November 2016 at 11:45 #265989
Anonymous
As mentioned there are straight flute carbide drills specifically for hardened steels up to 65Rc. As for coolant either nothing or flood, dabbing with a brush or the odd squirt is useless.

Andrew
11 November 2016 at 11:55 #265992
Jon Gibbs
Participant
@jongibbs59756
If it's just one or two small'ish holes I've had some success with cheapo spear-point tile drills.

I've drilled HSS this way but it needs quite a lot of pressure to cut and so Andrew's comments about coolant would seem appropriate – small dabs are unlikely to do much.

Jon
11 November 2016 at 12:23 #266001
Mark P.
Participant
@markp
When I worked for an aircraft engineering company we had some drill bits which would drill files and hacksaw blades, can’t for the life of me rember what they were though but the word wolfram drills pops into mind. I could be totally wrong though.
Mark P.
11 November 2016 at 13:30 #266011
Raymond Anderson
Participant
@raymondanderson34407
If you decide to use a Solid Carbide drill then you should be aware that they really need a rigid set up and won't tolerate a ANY flex, if there is flex then result "broken drill bit " I have a few Titex carbide ones, very spendy but very, very good, Any good Carbide drill will do the job, just bear in mind the rigidity issue

Stellite drills are another method for steels above 50Rc . They actually melt their way through rather than cut., still spendy though.
11 November 2016 at 13:36 #266013
John Haine
Participant
@johnhaine32865
In one of Guy Lautard's Machinist's Bedside Readers he describes the Cole Drill

The secret seems to be LOTS of pressure and slow running.
11 November 2016 at 13:36 #266014
MW
Participant
@mw27036
I'd just avoid working with hardened material if you could, it's a quick way to break alot of tools.

If you do decide to drill with carbide make sure you don't have any radial runout on the drill as it progresses or it will break. -Just as raymond described actually, happens more frequently than you'd like.

PS. John, that "cole" device is weird!,essentially looks like a simple drill column, i'm a little perplexed by the claims, i find using a pinion hand drill hard work, it's bizarre to imagine this being any easier.

Good on him for using a genuine jacobs in the assembly though. He's got a seriously messy workshop though, so much stuff in the photos i can't even see the bench top anymore!

Michael W

Edited By Michael Walters on 11/11/2016 13:50:52
11 November 2016 at 13:48 #266016
colin hawes
Participant
@colinhawes85982
Stellite will drill through any hardened steel. It has to be run dry at a high speed and a fair bit of pressure to create a lot of friction. Be aware that the area around the hole will be blued. Colin
11 November 2016 at 14:08 #266021
Jon Gibbs
Participant
@jongibbs59756
Posted by Michael Walters on 11/11/2016 13:36:22:

PS. John, that "cole" device is weird!,essentially looks like a simple drill column, i'm a little perplexed by the claims, i find using a pinion hand drill hard work, it's bizarre to imagine this being any easier.

Good on him for using a genuine jacobs in the assembly though. He's got a seriously messy workshop though, so much stuff in the photos i can't even see the bench top anymore!

I think it's untidy because it's the engine bay of a car
11 November 2016 at 19:23 #266064
John Reese
Participant
@johnreese12848
Regarding the use of carbide tipped masonry drills: I have done it. You do need to touch up the cutting edges on a grinder. You also need to run it very slow. The silver solder used to hold the carbide is the critical point. It does not handle heat.
11 November 2016 at 19:52 #266069
Roy M
Participant
@roym
If you look up one of my early posts, you will see a simple and cheap method of drilling HSS. If you need more info, just get in touch. Roy M
12 November 2016 at 09:01 #266132
Men Ifr
Participant
@menifr84251
Roy is that this thread

http://www.model-engineer.co.uk/forums/postings.asp?th=99795&p=2

I can see you have made some drill bits bit I'm not clued up enough to understand what you did? Did you cut them out of carbide?

In the same thread was a good suggestion to use a bar and cutting paste –

I will try 1 – the glass cutting cheapo bits I have if that fails a bar and cutting paste if I can get hold of some but to get something working grinding a slot with an angle grinder will suffice.
12 November 2016 at 10:22 #266143
D Hanna
Participant
@dhanna35823
Posted by Mark P. on 11/11/2016 12:23:08:
When I worked for an aircraft engineering company we had some drill bits which would drill files and hacksaw blades, can't for the life of me rember what they were though but the word wolfram drills pops into mind. I could be totally wrong though.
Mark P.

You most likely used Stellite drills Mark but at the price these days unless it's really a special need forget it!

http://www.knighton-tools.co.uk/acatalog/STELLITE_TOOL_BITS.html
12 November 2016 at 11:38 #266156
Neil Wyatt
Moderator
@neilwyatt
'Wolfram' is German for tungsten, so they may have been tungsten carbide?

Neil
13 November 2016 at 11:04 #266323
Men Ifr
Participant
@menifr84251
I can buy a 5mm colbalt bit from Arc Euro

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Twist-Drill-Bits/Drill-Bits—Cobalt/40-55mm

While I put my order in for the milling vice so that should work I assume. it's £2 so worth a gamble at any rate – will I need a smaller bit for a pilot first though?
13 November 2016 at 11:29 #266329
Tony Pratt 1
Participant
@tonypratt1
Men Ifr,

I can't see that you have told us what you intend to drill but the Arc drills are still only HSS, carbide is your best bet.

Tony
13 November 2016 at 12:11 #266334
Les Jones 1
Participant
@lesjones1
Find someone with an EDM machine. As Tony says it would help if you gave some idea of what you are trying to do. What thickness are you drilling through ? What diameter hole 0.5 mm ? 100 mm ?

Les

Edited By Les Jones 1 on 13/11/2016 12:12:14

Edited By Les Jones 1 on 13/11/2016 12:13:01
13 November 2016 at 14:28 #266354
Roy M
Participant
@roym
Men Ifr. The photo shows two stages of grinding the bit. On the right shows the first stage, grind the bit similar to a screwdriver about 1.4mm thick. Second phase is to grind the drill point angle at about 140-150 degrees. Then grind minimum back clearance. Run at about 1500 rpm. It does require a bit of effort to get it to start cutting but it works well. I have made plenty of these, and used them to drill out broken taps, and, as the other photos show, drill through part off blades and even digital callipers etc. Roy M.
13 November 2016 at 14:48 #266359
Men Ifr
Participant
@menifr84251
Woops i think I got cobalt and carbide mixed up for the drill bits I was looking at.

As usual one here it would seem i am trying to drill a 5mm hole in a digital caliper to make a dro.
13 November 2016 at 15:07 #266361
Les Jones 1
Participant
@lesjones1
Digital calipers are are made of stainless steel I have drilled them using cobalt drill bits from Arc Euro. (I think I have drilled some using normal high speed steel drill bits. )

Les.

Edited By Les Jones 1 on 13/11/2016 15:08:51

Edited By Les Jones 1 on 13/11/2016 15:10:37
21 November 2016 at 20:15 #267782
Men Ifr
Participant
@menifr84251
In the end I tried a cheap spear shaped glass drill bit at low speed and lots of pressure and that was making good progress until i crushed the tip with too much pressure. I then used a newly sharpened hss bit to contunue and whilst it screached badly and was much slower that got through in the end.
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