Removing a broken allen key ball end

[Pete.]

I had to get myself out of a hole - literally - today. I had to remove a grub screw from deep in a threaded hole. The top of the screw was about 12mm from the top of the hole. I foolishly grabbed a 3mm ball-end allen key, went to un-do the screw and it was so tight that the ball end snapped off in the screw. I could wobble it but no amount of tapping or poking would make it fall out - and I really needed to remove this screw! I tried grinding the end of the hex key flat in the hope that it would catch the top of the hex in the screw, but that didn't work. In the end, this is how I got it out.

I took the tungsten out of my tig torch and put heat-shrink sleeving on the last 30mm or so. I also ground the tip flat about 2.5mm wide with a small taper behind the tip.

I set my tig to stick weld, and 10 amps output. Poked the tip into the hole very carefully trying to keep it central. After a few false-starts I managed to just hold enough arc to fuse the tungsten to the little tiny ball end. After a bit of wiggling it popped out of the grub screw.

I then used a plain allen key to un-do the grub screw with no problems. There were a couple of rough bits where the tip had just arced the thread tops on the way in a couple of times but it screwed past them and after that the threads were nice and smooth. Here's the grub screw half-undone Which is all I needed to remove the pulley but it did come right out).

Just thought I'd share, in case someone else gets stuck with the same problem one day.

 

[eSCHEn]

Top marks for an ingenious use of dipping a tungsten

 

[BrokenBiker]

i assume you used the heatshrink to protect the threads? or did you use it to close over the offending part when heat occured after lighting up?

EDIT* read the bit i missed first time about fusing the tungsten to get it out

 

[Kent]

Will remember that ruse

 

[Robotstar5]

Useful tip, I'm a bit OCD about not using ball end keys to loosen a socket head pin

 

[Pete.]

Useful tip, I'm a bit OCD about not using ball end keys to loosen a socket head pin

So am I now mate!

 

[xmetal]

If the item is loose, I've put a small blob of blu-tack on the end on of a screwdriver, stick, etc to grab it. Very useful stuff such as when the rear light bulb of a disco drops down in the rear bumper bulb mounting!

 

[Pete.]

I used this trick again tonight and it worked well again. I'm renovating a Hardinge lathe which uses a cam-bolt to hold the compound slide. Well mine was seized in solid and when I tried to release it the bolt snapped leaving half of the cam inside the compound slide and pull-stud.
I tried drilling it so I could tap it and pull it out, but it was too hard. I then ground up a masonry bit and managed to partially drill it with that until the heat got into the broken bit and made it turn in the hole. After that I couldn't drill it any further without risk of marring the hole so I once again used the tungsten-dip technique. Took a few goes and 130amps to make the tungsten stick with enough hold but with a bit of patience and tapping the stud with a small hammer it finally gave up it's place and out it popped.

I even used the same tungsten as last time which I kept 'just in case'