Uni-Screw driver bit

[lemelman]

I'm in UK and have to remove two Uni-Screws holding a safe to the floor , but I don't have a driver bit. Despite trying every thing I can think of I've been unable to locate one. If I had the correct dimensions I'm sure I could make one. Can anybody give the official dimensions please? Or maybe somebody has an actual bit they no longer need.
Although both screws are somewhat inaccessible, I've managed to get a reasonable photo of a moulding of the screw head and one of the actual screw head.

 

[DJP]

I would try a grade 8 bolt head inverted and welded to a long bar. I'm not sure why there are smaller sizes as the biggest 6 point hole will give max grip and hence torque. I must be missing something as only the outer lobes would provide any security from ordinary tools.

This must be a magic trick where the inner portion rotates opposite to the outer portion. I'm interested in the solution. Perhaps it's drill proof.

 

[deverett]

Now that you have the impression of the bolt head, could you not machine up a male plug to those dimensions? Perhaps add a coupla thou to the AF dimensions if you are a bit wary - they could be filed/machined off if too large.

Dave
The Emerald Isle

 

[lemelman]

DLP. There's no magic trick and its not a security bolt. See

Dave. Each of the nested hex sockets is very shallow and the inaccessibility means that a single hex key just cams out. I had a go at making a bit from the best I could measure from the impression, but it failed. I shall try again but I'd rather like to get the official dimensions.

 

[Woodster]

https://outlaw-fasteners.myshopify.com/products/outlaw-impact-bits

 

[DJP]

It looks like a hardened impact bit is available but for Plan B you can always drill the screw heads off.

 

[john_reese]

It looks like the head of the screw sticks up above the surface. Can you get a vise grip on it?

 

[lemelman]

John, it does stick up, but not enough, and it's slightly rounded so the vise grip just slides off.

DJP, unfortunately, one of the screws is in a very restricted place right near the door hinge - and it appears that the screw heads are rather hard.

I'm reluctant to pay $4.99 plus shipping and customs to UK for something that I'll use just one. I'll try to get a better impression so I can make my own bit.

 

[DJP]

Perhaps start with an Allen bit and grind down sections to fit the deeper portion of the screw head. The bit that you create will need to be toughened so either start with a hard bit and grind or machine drill rod then heat it to harden.

If all this fails grind a slot in the screw head and use a flat driver bit on a ratchet handle. Some added pressure with a bar to ensure nothing slips. You may get one last chance to remove the screw.

Good luck.

 

[john_reese]

Can you slot the head with a Dremel and then use a regular screwdriver? Another possibility would be to cut flats on two sides of the head, then use vise grips.

 

[Howder1951]

When they get really ugly I usually fall to the carbide bit drilling the head right off. Ugly but effective?

 

[stragenmitsuko]

can you weld something like a long hex nut or even a throwaway socket wrench to it ?

 

[john_reese]

I just remembered Craftsman sold a set of screw extractors for screws with stripped out heads. They have 3 sharpened flutes that bite into the screw when turned to the left. I would offer to lend you mine but I just moved my shop and I cannot find anything yet.

 

[zebra7493]

The screw was pioneered by Birmingham fastener distributor and maker Forward Engineering
I think Tim Brooks is the man who developed it from its french patent
Forward Engineering may now be
Forward Industrial Products Group
If they no longer make or have them you could try a locking wheel nut remover available from motor factors
Like a 'negative' screw extractor ie the lefthand thread is on the inside.

 

[lemelman]

The screw was pioneered by Birmingham fastener distributor and maker Forward Engineering
I think Tim Brooks is the man who developed it from its french patent
Forward Engineering may now be
Forward Industrial Products Group
If they no longer make or have them you could try a locking wheel nut remover available from motor factors
Like a 'negative' screw extractor ie the lefthand thread is on the inside.

Thanks zebra7493, I contacted Forward Engineering and a very nice lady said, although they are as rare as Rocking Horse Poo, they have one that they will post to me. They then have only 2 left.
Amazing: thank you so much for your suggestion.