Drilling a hole through a screwdriver bit

[yetanothersmith]

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]

anneal and re-heat treat afterwards.

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

 

[Rorschach]

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]

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

 

[Billy_wizz]

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]

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

https://www.wonkeedonkeetools.co.uk/screwdriver-bits/how-are-screwdriver-bits-manufactured

 

[yetanothersmith]

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--]

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]

I’m not using cutting fluid

WD 40.

even better on aluminium.

 

[Torx]

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]

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]

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]

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

 

[yetanothersmith]

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]

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]

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]

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]

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]

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]

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.