How will I get this bxxxxxd out?

[pandos]

The first image is a hex headed M10 stainless steel grub screw, threaded into the pivot mechanism on a cast iron Southerly keel. It's purpose was to hold the stainless steel hinge pin in place.

The female hex part is filled perfectly with a snapped off Allen key.

I tried drilling this out but it is tool steel and have been unable to make any headway.

I have tried several new bits of a type which previously had no trouble on stainless steel. And gold coloured tipped bits (cobalt?) which the engineering shop advised were as good as he had.

Any suggestions?

I don't want to do too much butchery, indeed I may be able to avoid taking it out altogether but it would be sweet to fully disassemble things prior to cleaning them up.

 

[Refueler]

That snapped off key as you've found is a real pain ... it cannot be drilled ... it resists everything ...

I think the only way fwd - is a local engineer with an Oxy Acet torch to heat it up higher than you can and to maybe weld a bit to the key .. or to the screw itself ... new screw after ...

 

[Boater Sam]

And when you have done, buy some proper BS standard allen keys that you will not snap.
I would drill the screw at an angle to one side around the allen bit, its softer. Drill till you are full depth and the bit should be able to be pried out.
Best way is to weld a nut onto the screw, filling the center with weld on to the screw and bit. The heat will let you unscrew the screw too.

 

[Daydream believer]

A friend of mine had a prop shaft coupling with a set screw that would not release. He spent some weeks trying to release the screw & messed up a few drill bits trying to drill it out. Finally he did what we all told him to do & let our harbour master have a look. He just belted the coupling with a club hammer & it came off in under a minute.
The point I am making is that the set screw may be like his & only engaged in a small dimple.It may only be sitting on a woodruff key or a machined flat. If so the item you want to remove could be drawn away with a simple hydraulic hub puller etc. If it cannot be gripped then a set up could be made with a bolt to push the hinge pin out rather than pull it. Can it be drilled in the end, taped & a bolt fitted to enable pulling? The OP may be able to belt it out with a good quality large drift & decent weighted hammer. The set screw would just score the shaft a little , but that can be filed flat. Once off the inner point of the screw can be ground flat with a dremel & a new hole for a set screw dilled & taped, leaving the old one where it is. Which is what I did for my friend.
This may be of use to the Op- it may not

 

[rogerthebodger]

Get a Dermel with a find grinding bit. I used this to "drill" a hole in a hardened chain saw blade

 

[Frayed Knot]

I ask this as a retired carpenter who knows almost nothing about metal and engineering so I’m quite prepared for ridicule…
I’m pretty certain that metal can be softened (annealed?) to allow easier working. Can anyone come up with a way to do that to the grub screw in situ?
Edit: I meant the broken pice of allen key.

 

[snowbird30ds]

Your best friend will be someone with a portable tig welder, idealy weld a nut over the whole lot but the allen bit may make the weld brittle, if you can weld something to the allen bit only that can be attached to a slide hammer you may be able to get that out then drill through the grub screw and weld a nut over, the drilling relieves the thread a bit and when welded it tends to pull in as it cools making it looser.
Most times I have done this is with steel in aluminium and conveniently on a bench not in situ so good luck.

 

[chriscallender]

One way of getting hardened steel out is to use its brittleness and shatter it out with a hammer and sharp point. I've done that before with thread taps that broke off in the hole. Not sure if you have good enough access here, but maybe worth a thought.

 

[Poignard]

What is holding the broken bit of Allen key in place?

Gravity and rust.

What I would try, before taking more drastic measures, is to first soften the rust with Renaissance Metal De-Corroder (because I happen to have some and I know it works well).

Then I would try and loosen the remains by tapping to and fro with a sharp thin centre-punch.

If successful, the broken piece could be remove with Blutack.

If that didn't work, I'd ask for advice on the YBW forum

 

[PCUK]

There are several videos on You Tube showing exactly how to overcome this problem using mig. Search broken bolt removal.

 

[Metalicmike]

I have drilled hardened steel with a masonry bit, you will need to grind a cutting edge as they are not designed for cutting and will need to avoid overheating the tip, cut on a slow speed with a lot of pressure. it would help if you start with a small pilot hole using a diamond Dremel bit.

 

[Boater Sam]

You will not anneal tool steel in situ.

 

[Bouba]

I have an induction heater that is made for those sorts of jobs....they are cheap and nice to have in the tool box....call it an early Christmas present to yourself
Amazon.co.uk

 

[KevinV]

As per others above I'd try getting the key out before trying anything else - a small tap in the opposite direction to which you snapped it may be enough to dislodge it. Otherwise as Poignard suggests, acid to dissolve the rust would be a good start, a bit of a wiggle and it should come out.

Then try again with an impact gun, tightening momentarily first.

 

[prestomg27]

If you can weld then you could weld a nut on top. Or if not cut a slot in it with a 1mm angle grinder cutting disc. Then use a screwdriver impact bit on an impact driver to turn it.

Youll cut a little into the cast iron keel but that doesn't matter.

 

[doug748]

They used tap-zappers on high worth engineering items, they were very expensive and not portable. I see the Chinese have been on the case however:

Amazon.co.uk

Not suggesting you buy one but, if all else fails, there may be some local engineering firm that has a lead on one. You do need reasonable access from above though.

.

 

[PCUK]

I have an induction heater that is made for those sorts of jobs....they are cheap and nice to have in the tool box....call it an early Christmas present to yourself
Amazon.co.uk

Don't they need to be around the bolt?

 

[Bouba]

They used tap-zappers on high worth engineering items, they were very expensive and not portable. I see the Chinese have been on the case however:

Amazon.co.uk

Not suggesting you buy one but, if all else fails, there may be some local engineering firm that has a lead on one. You do need reasonable access from above though.

.

That’s a neat thing to have !....but I can’t help feeling that if I’ve got the piece in my workshop...then I’m gonna a cheaper way to do it

 

[Bouba]

Don't they need to be around the bolt?

Yes...I cannot see for certain in the picture....but it does look like it’s raised up from the surface

 

[Metalicmike]

That has grown roots, its not going anywhere.