Paging those good with rounded bolts - advice needed.

I can see why it wouldn't work... on resessed allens. I'm thinking of
the little fuckers that hold my forks together

 

Bloody hell, hasn't everyone got a set of these, call yourselves tool
porn stars ?

Bloody amateurs ..

Paul.

 

Convince me otherwise by all means but I can't see it. If the threads
were stuck enough that head was going to come off why would what seems to
be little more than an auto adjusting hex mole grip make any difference?

 

I don't need to convince anybody as to how they remove seized fasteners
but there are very good reasons why you don't keep forcing something
until it finally moves.

 

Dunno, they've been around for about 15 years, RS components sell them,
or something very similar, and they call them Metrinch

 

AFAICT, they aren't "forcing until it finally moves", merely compensating
for the fact that there ain't no corners on the bolt head any more, since
it appears to have been made from furry brown cheese.

Or, at least, that's what I'm using 'em for.

 

Sneaky little word, that "recessed".

Hmm. External version. That's an interesting thought.

 

Nah, they're the flank-drive ones that Hog mentioned.

 

Yebbut one definition of "it finally moves" is getting it undone. If it
achieves that then what is wrong with it?

 

TBQH, if it doesn't move after a sharp tap, i'll attack it with plus
gas, a shock to the bolt head or a bit of heat.

Turning a seized fastener slowly isn't a good idea [1]. Heating it
until it anneals it isn't either.

Paul.

[1] that's a good recipe for shearing it off

 

The cheapo way of getting your 7/16 socket on is to grind the end of the
socket as flat as you can on the face of a grinding wheel - take out the
bevel on the entrance to the socket so you effectively have a cutting edge
at the entrance to the socket, a 12 corner socket will go on easier but will
just strip again if the bolt is really jammed.

 

However, it is possible to break one without moving the offending bolt one
tiny bit. Mined ewe, said bolt also resisted red heat, penetrating oil
and a foot-long stillson wrench so it was a particularly obstinate example
(in the end I had to cut the fucker off and drill/helicoil).

 

True, but very often the head has been mashed by previous fuckwittery
and the ability to get a grip and apply suitable persuasion with
rattle gun will be enough.
If the correct tools had been used in the first instance it would not
be "stuck", just a bit tight.

 

Tragically not at 12mm, though.

 

Stopping turning it once you've got it going is contra-indicated as
well. Once it's on its way, keep it going. Stop for a rest and it
welds itself in place, simultaneously being affected by the heat
generated so that when you return to it, it snaps like elderly
liquorice.

 

We shall see. I have bought a set and will report on their first use,
whenever that may be.

<Peruses carcass down side of house>

In the near future, I suspect.

 

http://cgi.ebay.co.uk/13-pc-Professionals-Industrial-Set-Irwin-Hanson-54113-/360352585264

Rather pricey though...

 

Pikey git

When it comes to decent tools to do a specific job and avoid potential
hours of arse-ache, followed by the inevitable job of taking the
bastard thing to someone who *does* have the right kit, virtually any
price is "cheap".

 

I don't see how this would help to get a 7/16 socket (11mm) onto a 12mm
bolt head.

I take your point if the face of the bolt is rounded but there's useful
hex below it, or, as is the case with a lot of filtery type bolts, the
hex is really shallow - the chromed variety springs to mind, where the
vertical hex face is 1.5 - 2.0mm high, but the bolt head looks good, as
it is slightly domed. Nice to look at, a right bugger to unseize
unless you use a flat-faced socket such as you describe.


As far as the OP goes, I'd go along with a previous suggestion and get
the thing accessible first. Lie it on its side on a mattress, old tyre
or something that'll prevent damage. Clean the target area off and get
to know your enemy - there might be some useful hex hidden under the
crud. Use a Flank Drive(TM) or surface drive socket that'll drive on
the flats, ground off flat as IF describes, for maximum purchase.
Unless you can get the thing inverted, I wouldn't bother with
penetrating fluids, as that would just lube the bolt head and wouldn't
get into the threads - heat, similarly, is pretty useless in this sort
of situation.

If all else fails (like grinding a screwdriver slot and impact driving
or hex-shank screwdrivering it), a small sharp cold chisel: make a vee
in a flat, then raise a (thickasyoucan) curl of bolt steel. Swap to a
less sharp chisel (you don't want to cut the curl off) and tap - in the
unscrewing direction (obviously) with the chisel aligned to the circle
of rotation within the hex. That /always/ works.

 

Hammering in an over-sized Torx bit often works with rounded out
allens. In fact I can't think of a time when that hasn't worked for me,
most recently last weekend.