How to round off a bolt (for security)?

[Doodlebug]

I am planning to use some tex screws (with a hex head) to secure door hinges to our boat. Problem is that will leave me with doors which are very easy to undo with a spanner.

 

Does anyone know of a tool or method to round them off once in. I imagine there could be a tool that goes in a drill which might be used for rounding off rivets which might work.

 

A slow method might be to grind off each corner with an angle grinder

 

Thanks!

[Phil Ambrose]

There are screws that have sheer off heads also screws that can only be done up but not undone.

Check out security screws, also Screwfix.

Phil

[David Mack]

Just keep tightening them using a slightly oversize spanner. That usually rounds off bolts!

[john6767]

use one of these types of screws perhaps http://www.tamperproof.com/categories/products.html

[The Boater]

If 8 ml metric is not too large use the steering lock shear bolts that fit just about every car on the road, maybe two each side of the door aperture,

[Chewbacka]

If 8 ml metric is not too large use the steering lock shear bolts that fit just about every car on the road, maybe two each side of the door aperture,

If you are using bolts, then why not coach bolts?

[magnetman]

I'd drill and tap and use stainless steel studs with shear nuts (assuming its a steel cabin)

 

Or use socket button machine screws and drill out the socket after fitting.

 

Edit to correct first part

Edited August 10, 2016 by magnetman

[magnetman]

 

Or countersunk socket cap and drill out the socket. Same effect but would be more flush.

 

Tamper proof torx fasteners are interesting but as one can readily get the tools to remove them then how useful are they? Seems to me that using a fastener with an internal socket drive like an Allen type is quite good because of drilling out the socket and the action of doing the drilling will also drive it tighter. Only thing being it would he fairly straightforward to drill the whole head off ..

[Robbo]

I am planning to use some tex screws (with a hex head) to secure door hinges to our boat. Problem is that will leave me with doors which are very easy to undo with a spanner.

 

Does anyone know of a tool or method to round them off once in. I imagine there could be a tool that goes in a drill which might be used for rounding off rivets which might work.

 

A slow method might be to grind off each corner with an angle grinder

 

Thanks!

You can get tools that are designed to unscrew stripped screws or bolts so I wouldn't use that method.

[bizzard]

Doodle says he's using Tec screws which drill and tap their own thread as you drive them in. I presume he can't get behind to put nuts on bolts.

Doodle says he's using Tec screws which drill and tap their own thread as you drive them in. I presume he can't get behind to put nuts on bolts.

Very easy to just file the corners off the screw heads by hand. Could use an angle grinder with a stone in it but he would have to be careful. A small 12v Dremel with a wee stone in it would do it fine.

[magnetman]

What about hacksawing the hex head off and just leaving the flange ? Could probably get a junior hacksaw in close enough. Would need to be deburred afterwards

Maybe use a hand file for deburring

[mross]

just Google one-way screws! B&Q sell them. This is what Bizzard was describing. DIY or buy ready made.

 

[magnetman]

Is there enough grip to self tap it into steel? I can see the driver bit slipping

[Robbo]

Is there enough grip to self tap it into steel? I can see the driver bit slipping

I would drill and tap first as I'm guessing you can't get the one way screws in that are self scew/tap.

Edited August 10, 2016 by Robbo

[mross]

It might work if you used one of those claws for holding the screw to the bit. Or you could drill a pilot hole first, just smaller than the core of the screw. But a tapped hole and matching thread would be stronger than a self-tapper.

[bizzard]

just Google one-way screws! B&Q sell them. This is what Bizzard was describing. DIY or buy ready made.

 

No, it wasn't what I meant. The Tec screws I know of drill and tap their own thread as you drive them in. They have a drill bit lead and slotted thread cutter built in. As far as I know available with hex heads only.

[mross]

No, it wasn't what I meant. The Tec screws I know of drill and tap their own thread as you drive them in. They have a drill bit lead and slotted thread cutter built in. As far as I know available with hex heads only.

Sorry for misquoting you.

[magnetman]

No, it wasn't what I meant. The Tec screws I know of drill and tap their own thread as you drive them in. They have a drill bit lead and slotted thread cutter built in. As far as I know available with hex heads only.

Googling tek screws shows exactly what you describe - with a handy little flange below the head so the head could be cut off and it would still hold securely.

 

I prefer drilling and tapping to self tapping types in steel personally.

 

I've never used tek screws - maybe they are effective

Edited August 10, 2016 by magnetman

[Robbo]

Googling tek screws shows exactly what you describe - with a handy little flange below the head so the head could be cut off and it would still hold securely.

 

I prefer drilling and tapping to self tapping types in steel personally.

 

I've never used tek screws - maybe they are effective

I've used them, but for this job I wouldn't recommend them as it would be a better finish with the one way screws.

 

Anither method would be forget about securing the hinges and use another lock on the hinge side (pref more than one).

[bizzard]

Tec self drilling and tapping screws are also available with domed Philips + head. I've just found some of mine which I'd forgotten about. In stainless steel.

Edited August 10, 2016 by bizzard

[WotEver]

Generally "Tek" with a k.

 

Interesting pdf of one manufacturer's range here:

http://www.evolutionfasteners.co.uk/downloads/tech/0/201107261044197206evolutionheavytekslores2.pdf

 

Tony

[Robbo]

Using these type of bolts, believe they are called dog bolts, may be better solution than trying to secure the hinges..