# Drilling a hole through a screwdriver bit



## yetanothersmith (14 Jan 2021)

Hi everybody. This might be a bit of a random one but I want to drill a 3-3.5mm hole through a standard PH2 1/4 inch hex screw bit for a multitool project I’ve been playing around with (corona lockdown makes work for idle hands!) You may not be surprised to learn that they’re really hard! Most centre punches bounce off them. HSS drill bits won’t touch them either. I’ve had partial success with cobalt bits but have yet to make it all the way through before the bit stops cutting. I’m keeping my spindle speed low, not applying loads of pressure and hopefully not generating too much heat (although I’m not using cutting fluid). Any bright ideas of where I go from here?
Thanks in advance,
Pete.


----------



## marcros (14 Jan 2021)

anneal and re-heat treat afterwards.

it wont take much to do, a plumbers torch will easily do it.


----------



## Rorschach (14 Jan 2021)

They probably aren't made of an alloy that is easy to anneal or harden, like HSS.

Carbide drill would definitely do it, but at that size they are very fragile.


----------



## Torx (14 Jan 2021)

Buy a chineseum set from Poundland and then heat treat them properly when done?


----------



## Billy_wizz (14 Jan 2021)

Torx said:


> Buy a chineseum set from Poundland and then heat treat them properly when done?


Surely they won't have the properties to be heat treated properly


----------



## marcros (14 Jan 2021)

hmmm, may be one of those "it depends what you have" issues. 









How are screwdriver bits manufactured? - Wonkee Donkee Tools


How are screwdriver bits manufactured? Shop for Screwdriver bits Screwdriver bits are either forged or machined. Each have their own particular set of characteristics. Forged bits Forged screwdriver bits are made by heating up the metal and hammering it into shape. Applications Forged bits are...




www.wonkeedonkeetools.co.uk


----------



## yetanothersmith (14 Jan 2021)

Thanks for the replies everybody. I hadn’t thought of bringing some serious heat into the equation. I stumbled across this video on spot annealing which I might give a go.


----------



## --Tom-- (14 Jan 2021)

Carbide Masonry drill sharpened on a diamond stone has worked for me on hardened tool steel.

carbide drill will do it to, but as has been said they’re fragile and if you snap it in the whole you’re going to be starting again.


----------



## Misterdog (14 Jan 2021)

yetanothersmith said:


> I’m not using cutting fluid



WD 40.

even better on aluminium.


----------



## Torx (14 Jan 2021)

Billy_wizz said:


> Surely they won't have the properties to be heat treated properly



You’re most likely right, it was a semi-tongue in cheek response.


----------



## Billy_wizz (14 Jan 2021)

I'll try to remember to ask the old man tomorrow as he'll know! whether the job is worth the cost however lol


----------



## Cabinetman (14 Jan 2021)

To my mind the question is why, and would it be possible to do it another way, you obviously want to attach something to the hexagonal shaft, could you not do it with a hexagonal hole in something else epoxied onto the shaft? Ian
Thinking outside the box, I was never in it to start with!


----------



## Billy_wizz (14 Jan 2021)

I would be tempted to try the Bosch carbide tipped universal drill bit!


----------



## yetanothersmith (15 Jan 2021)

Misterdog said:


> WD 40.
> 
> even better on aluminium.


Thanks for the tip. Am I right to say that the purpose of cutting fluid is cooling / heat dissipation or does it aid cutting?


----------



## yetanothersmith (15 Jan 2021)

Cabinetman said:


> To my mind the question is why, and would it be possible to do it another way, you obviously want to attach something to the hexagonal shaft, could you not do it with a hexagonal hole in something else epoxied onto the shaft? Ian
> Thinking outside the box, I was never in it to start with!


"Why" is the question my wife asks of most of my little projects! I'm looking to keep the piece as small as possible and a keyring split ring would be going through the hole (see attached pic). Ideally I want to keep the piece as small as possible. I agree that attaching something else to the bit would help me side step the immediate problem but it isn't quite what I want to achieve. That said its always good to look at a problem from another direction, thanks.


----------



## yetanothersmith (15 Jan 2021)

Billy_wizz said:


> I would be tempted to try the Bosch carbide tipped universal drill bit!


Is that one of their masonry bits that I could sharpen up? Do they go down to 3mm?


----------



## Billy_wizz (15 Jan 2021)

yetanothersmith said:


> Is that one of their masonry bits that I could sharpen up? Do they go down to 3mm?


There also called multi construction now shouldn't need to sharpen I've used them in the past on screws and bolts just need to make sure screws are rounded off first or the tip brakes up but there basically a pre sharpened bit with a carbide tip!


----------



## yetanothersmith (15 Jan 2021)

yetanothersmith said:


> Is that one of their masonry bits that I could sharpen up? Do they go down to 3mm?


Thanks. I'll give that a go. Even if it doesn't work (which I hope it will) its all good learning.


----------



## Gerry (15 Jan 2021)

Why not use a small neodymium magnet on the keyring possible slightly recessed in a tube then just snap the bit on and off when needed. That way no modification to the bit is needed, One size fits all.

Gerry


----------



## yetanothersmith (15 Jan 2021)

Gerry said:


> Why not use a small neodymium magnet on the keyring possible slightly recessed in a tube then just snap the bit on and off when needed. That way no modification to the bit is needed, One size fits all.
> 
> Gerry


Thanks Gerry. The plan is to use existing keys as the means to drive the bit so I still need the slot in the top (easy enough to cut in with a thin cutting disc and diamond files). I know magnets are strong but if it can detach when you want it to it can also detach when you don't want it to so the risk of loosing the bit is greater (but easy / cheap to replace I suppose). I'm also mildly concerned about magnets around bank cards on something that will be carried in a pocket potentially with a wallet. Not sure if this is just an urban myth though.


----------



## Jelly (15 Jan 2021)

Rorschach said:


> Carbide drill would definitely do it, but at that size they are very fragile.



If he's sufficiently determined making a custom drill bushing out of scrap steel would mitigate the risk of snapping... 

Although I'd probably just take the chance and center drill it then run the drill bit fast, whilst feeding with consistent pressure.


----------



## Inspector (15 Jan 2021)

Look for a company that does wire EDM cutting (Electric Discharge Machining). It can cut very thin slots and holes. They are used by companies cutting muzzle brakes in the end of rifle barrels among other things. The other option would be an industrial laser. With either the more you get done the cheaper they will be. Make lots and if they work out you have your little web business.

Pete


----------



## Rorschach (15 Jan 2021)

Jelly said:


> If he's sufficiently determined making a custom drill bushing out of scrap steel would mitigate the risk of snapping...
> 
> Although I'd probably just take the chance and center drill it then run the drill bit fast, whilst feeding with consistent pressure.



Yes that would help. I personally find it's the swarf that causes the problem, get's jammed in the flutes and because it is hard it doesn't crumble like like normal chips. Have to peck drill gently.


----------



## Ttrees (15 Jan 2021)

How long does a good bit (which is sharp) last, before it starts talking to you?

Did you try them in some mild steel first to check if they were actually sharp?

Drilling some stainless recently and the new quality bits from a proper engineering place were not able to cut at all!
I was very surprised at that, and all was sound once I took some old ones to the bench grinder.
Once it starts talking back to you, stop and sharpen it, you're only wasting your time
otherwise and hardening it, a sharp bit will likely get under it.

Good luck
Tom


----------



## --Tom-- (15 Jan 2021)

I’m intrigued so will give it a go tomorrow on a spare pozi 2 tomorrow.


----------



## TFrench (15 Jan 2021)

If someone asked me to do it I think I would try a solid carbide stub drill in the milling machine. Rennie tools have them on eBay for about a fiver including postage.


----------



## yetanothersmith (16 Jan 2021)

--Tom-- said:


> I’m intrigued so will give it a go tomorrow on a spare pozi 2 tomorrow.


Let me know how you get on.


----------



## yetanothersmith (16 Jan 2021)

So I fired up the blow torch with the screw-head end in dipped in snow and heated up the hex end until it glowed red. After that the centre punch left an indent and the cobalt drill bit went through without too much fuss. I don’t know the quality of the bit i was using; it wasn’t a Dewalt one and could well be a Chineseium one but either way it now has a hole where I wanted it. Thanks for all your help guys.


----------



## GLFaria (16 Jan 2021)

Hi
Are not these bits case-hardened by chance? If so, they are probably made from low carbon (<1% C) steel, not susceptible to proper tempering/hardening
In this case the way to go would be to grind through the hardened "skin" with a small abrasive rotary tool (Dremel-like), the underlying steel could then be drilled with a HSS drill bit.

Mind you, I am not speaking from experience - I never felt the need for drilling through a bit. That's why I am using the conditional. I may try it some day when I have nothing better to do (improbable)
Cheers


----------



## gregmcateer (17 Jan 2021)

Nice work.
Now you can go burgling without even going tooled up!


----------



## yetanothersmith (17 Jan 2021)

gregmcateer said:


> Nice work.
> Now you can go burgling without even going tooled up!


Nothing to see here officer!


----------



## flying haggis (18 Jan 2021)

if you dont want to drill your own bits








Key Ring Bit Screwdriver Bits Bit ´S Pendant Ring | eBay


We usually ship everything within 24 hours (excluding personalized items such as t-shirts, stamps and stickers. International shipments to Europe are usually post 3-4 days with you. However, it can currently take up to 1-2 weeks. Unfortunately we cannot influence this. You can always get the...



www.ebay.co.uk


----------



## hugov (20 Jan 2021)

It is possible to DIY your own improvised EDM setup at home, although it is a project unto itself... check out


----------

