How to drill hardened steel

[Men IfrParticipant @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…

[Men IfrParticipant @menifr84251]

[Douglas JohnstonParticipant @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

[Dave plus / minus 40 thouParticipant @daveplusminus40thou]

You can use a masonry drill bit (with a carbide tip) at a push, sharpen the cutting angle and use coolant

Dave

[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

[Jon GibbsParticipant @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

[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.

[Raymond AndersonParticipant @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.

[John HaineParticipant @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.

[MWParticipant @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

[colin hawesParticipant @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

[Jon GibbsParticipant @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

[John ReeseParticipant @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.

[Roy MParticipant @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

[Men IfrParticipant @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.

[D HannaParticipant @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

[Neil WyattModerator @neilwyatt]

'Wolfram' is German for tungsten, so they may have been tungsten carbide?

Neil

[Men IfrParticipant @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?

[Tony Pratt 1Participant @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

[Les Jones 1Participant @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

[Roy MParticipant @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.

[Men IfrParticipant @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.

[Les Jones 1Participant @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

[Men IfrParticipant @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.

[Author]

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