Rounded Allen bolts!

[Clive]

Right O gods of all things Manky and mechanical!!

I've got a problem. I've got ten button cap allen bolts that are driving me mad!! I'm sure they're made of plasticine or something! Every time I try and free them off all I end up doing is rounding the holes!! I've tried penetrating oil, heat, giving them a tap, and nothing but even more rounded holes!! 

Anyone got any other top tips as to how to get these bolts out, as I'm kind of stuck, and can't progress til these are out??

Thanks in advance

Clive

[morrag]

Cap head bolts are tough cookies, and I have rarely known them to "round". are you sure they are in fact Allen key heads, and not one of the many multi fluted head types available now,and favoured by many of the car makers, which may take an Allen key, but not as a proper fit, and then the obvious happens! worth checking. If not that ensure you're not using a near enough sized key, i.e Metric key on an Imperial cap head or vice verse, other than that you must have some "Chinese" quality cap heads!!! Morrag

[Clive]

They're standard Suzuki 5mm Allen head size bolts buddy, but seem to have been on there since it rolled out the factory!!

[voodoo]

Ive got a set of reverse thread drill bits that are designed to remove rounded screws etc that you are willing to try out?...Voodoo...

[Clive]

I've got some of them buddy, and they were tomorrows attempt, was just seeing if there was something I was missing!!! But thanks!!!

[Cabman77]

What size bolts/screws are they Clive? If they`re only small (M4 or M5) and they`re button head as opposed to caphead (your standard allen bolt) then the size of the allen key itself is a big part of the problem. I`ve actually filed an AF allen key to fit a metric button head before and that does work because you`re able to make it fit tight. Also try using a Torx bit. get a good fit and one of them will shift it.

[Clive]

They're M6 or M8 (I think. Never worked out how to work that out, but then I am thick  ). Might give the Torx thing a go before destroying them with the removal doo dah!!!

[Cabman77]

you measure bolts etc by they`re thread size Clive with allen screws that bears no resemblance to the size of the allen key required. Buttonheads need a smaller key than capheads (standard allen bolts).

[Tony oily bike]

Also try using a Torx bit. get a good fit and one of them will shift it.

I was gonna suggest using a 'Torx' style tool too.

If you can get one that fits into a socket (see piccie), you can give it a mechanical tap (with a hammer  ) so the fins of the torx dig in to the fastener
Then you can get some serious purchase/leverage by using a socket wrench, which should also keep things as square as you can, whilst keeping pressure on the torx (so it stays 'dug in' to the allen head).

I was once told that if a fastener doesn't want to undo, try a very small tightening action, sounds strange but it may help. (it may of course snap the whole head off, no guarantees....)


If you ever find the hex of bolts/nuts too rounded for a spanner or socket to do its stuff, Metrich make really neat spanners & sockets the grip on the flat of the hex, not the corners.
They've rescued me more than once.
http://www.metrinch-tools.com/website/introductie.php?language=gb

[Cabman77]

If you ever find the hex of bolts/nuts too rounded for a spanner or socket to do its stuff, Metrich make really neat spanners & sockets the grip on the flat of the hex, not the corners.
They've rescued me more than once.

Likewise 

[nabsim]

As all the above really except to add on some really tight disk retaining button heads I have used an impact driver with the correct allen bit. If you do this do make sure you have the driver set the right way before belting hell out of it

[Clive]

Four hours, and six of them are out!!!!!!!! Ended up, after exhausting all other options, cutting a groove in them and smacking a screwdriver with a sledge hammer to free them!! 'Might' need new ones!

The other four are getting the backs angle grinded off tomorrow, and nuts added to the backs of the new bolts!

[Tony oily bike]

Sounds like you're having a great time............

Depending on where these darlings are, maybe a bit of copper-slip when reassembling? 

[Manky Monkey]

Loony recently had a set of car wheels in at his workshop to paint for a customer. They had "allen bolts" all around the rims, to imitate split rims, (wheels made in several pieces bolted together). Despite going through his collection of Metric & Imperial allen keys & Torx bits several times, he just couldn't find anything that fitted. They seemed to be a weird size all of their own & nothing would turn them. I'd had a similar problem on some wheels years ago -they weren't bolts at all, but imitations, just for show. Cheap alloy heads with splined shafts rather than threads. They just tapped into the holes with a hammer.

[Cabman77]

Four hours, and six of them are out!!!!!!!! Ended up, after exhausting all other options, cutting a groove in them and smacking a screwdriver with a sledge hammer to free them!! 'Might' need new ones!

Sorry forgot the "Big Hammer" solution..............which is quite surprising really considering my tool box only used to have 4 tools in it, small hammer, medium hammer,big hammer and centre dot (=torque wrench)