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Drilling a hole in an Allen key, no really!

Bit of a challenge. I need a 4mm Allen key with a 3mm hole drilled into it! Why, you may well ask! A customer has a door entry/security system that operates a maglock above the door. For some bizarre reason this is the only unit on site that is fixed to the bracket with a 'security pin hex socket screw'. This is in a recessed hole about 20mm deep. I cannot use a standard hex security bit as it is not long enough to 'bottom out' in the recess. The manufacturer denies ever having made such an item, I can understand why, resulting in not being able to source a correct key. I have tried drilling the end of an allen key with limited success. I only have access to a hobbymat lathe and a bench drill. I even tried heating key to red hot and dunking in water to try and soften the metal prior to drilling...crashed and burnt on that one as well!!! My main problem is trying to centre punch the end of the key to start the drill off, I am just getting blunt centre punches. Has anybody got any suggestions? or should I just dismantle the unit and replace the screws with normal ones? Many thanks in advance

Reply to
Clive Dive
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Well, for one, heating the Allen key to red hot and dunking it in water probably made it harder, not softer. To get softer, heat it to red and cool slowly.

Can you access the screw in question? If you can, consider either drilling or punching off the pin.

Lots of places sell screwdriver bits sets that have security Torx tips in them. Find the one that fits the best and try it. I have, on occasion, resorted to forcing a slightly too large tip into a screw with a hammer to remove it.

Worst case. Drill the head off the damn screw and replace it once the plate is off.

Cheers Trevor Jones

Reply to
Trevor Jones

Your heat treatment will harden the key not soften it. You need to heat it to red hot and then let it cool sloooooowly as possible. You should be able to drill it then starting with a centre drill. Are you sure about the sizes? 3mm hole in a 4mm key will be very weak.

Bob

Reply to
Bob Minchin

Ah, classic schoolboy error in cooling too quickly! I'll try cooling it in some hot sand instead, thanks. Yep, it is 3mm hole in a 4mm key! I guess that the pin is only to prevent a normal key fitting and the 'fit of the pin into the hole' replaces the 'meat' that was removed during the drilling? I'll give it a go tonight, nowt on tele! If it fails I'll have to knock out the pin tomorrow.. Many thanks for the replies.

Reply to
Clive Dive

8<

As others have said, this is the opposite of what is needed as it will harden the key.

Perhaps you could approach it from the opposite direction and drill a hole in some soft-but-hardenable steel and then (case) harden it.

You say a standard 1/4" hex bit it too short, but which part of it needs to be longer - the 4mm hex or the 1/4" hex? IOW, is there sufficient clearance for the 1/4" part? If you (silver) soldered a rod to the end of a standard bit, would that do?

Reply to
John Montrose

Reply to
Andrew Bishop

Would one of these do ?

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Or go to rswww.com and search for stock number 208-1893.

-adrian

Reply to
Adrian Godwin

stock number 208-1893.

Now why couldn't I find them?, absolutely perfect. I'll try my home made 'effort' tomorrow, then when that fails I'll order from RS. Many thanks

Reply to
Clive Dive

On or around Wed, 10 Jan 2007 18:44:40 +0000 (UTC), "Clive Dive" enlightened us thusly:

typical security pins are much smaller than that.

Reply to
Austin Shackles

On or around Wed, 10 Jan 2007 20:18:15 +0000, Adrian Godwin enlightened us thusly:

waste of time posting RS urls, they expire.

that's more likely to work.

Reply to
Austin Shackles

On or around Wed, 10 Jan 2007 18:44:40 +0000 (UTC), "Clive Dive" enlightened us thusly:

don't forget to re-harden and then temper the key after you drill it...

Reply to
Austin Shackles

In article , Clive Dive writes

It is for this type of thing that God created LH drill bits.

That, and Japanese motorcycle bolts made from Cheddar.

I wouldn't be without mine.

Reply to
Nigel Eaton

I actually want to tighten it up, thus the dilema. It only came loose after the company in questions' 'Director of Percussive Maintenance' decided to make an adjustment which was not required and the maglock [approx 1Kg] fell on his head; if at this point you should laugh then you are a bad person ;) If tonights home made effort does not work then I think I will replace the offending screws. Its a bit of a ball ache but would save future struggles. Many thanks for the replies

"TriMix, I've tasted it! It's the future"

Reply to
Clive Dive

Slightly.. I just went out and measured a 4mm hex security driver and the hole is 2.5mm diameter.

Wayne...

Reply to
Wayne Weedon

In article , Clive Dive writes

Oh. That's easy! RH drill bit... :^)

LOL!

Oops.

I'd do just that, I think.

Reply to
Nigel Eaton

Took it to bits. tw4tted pins out with small punch. re-assembled. Tested. 10 minutes total time. Mission ends.

Reply to
Clive Dive

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