Buggered bolt

[Pieoftheday]

Hello, a bolt on my bike luggage rack has become well and truly stuck,the Allen head recess has rounded off and the outer edge is smooth so no chance of grip, so I'll have to drill it out. I'm guessing it a stainless steel bolt but I'm not 100%, what type of drill bit do I need.? Also should I get a drill bit 1 or 2 mms smaller than the thread of the bolt? I have done this before but it was ages ago,cheers Jim

[Pigmy Pony]

Hi James, your thread title really piqued my interest, turns out it has nothing to do with you abusing a certain world-class Olympic sprinter. :(

It's a long time since I've had to deal with this sort of thing, but I seem to remember buying a tool which you screw into the end of the bolt after drilling into the back of it first, then you clamp some mole grips onto the tool and it brings out the bolt with it. It may have been called a stud extractor, was about the size of a nail punch and it didn't cost much.

[mikmas]

Depending on the size of the head (and whether you have a steady hand) might be worth trying to hacksaw a groove across the diameter and then use a screwdriver. Have done this before with some success. My experience with drilling out bolts is that I usually swear a lot and bugger up the existing screw thread either way.

[Pigmy Pony]

Depending on the size of the head (and whether you have a steady hand) might be worth trying to hacksaw a groove across the diameter and then use a screwdriver. Have done this before with some success. My experience with drilling out bolts is that I usually swear a lot and bugger up the existing screw thread either way.

and gripping tightly a sturdy screwdriver in the newly-made groove, and twisting it anticlockwise while hitting the top of the screwdriver can also help.

[Pieoftheday]

Hi James, your thread title really piqued my interest, turns out it has nothing to do with you abusing a certain world-class Olympic sprinter. :(

It's a long time since I've had to deal with this sort of thing, but I seem to remember buying a tool which you screw into the end of the bolt after drilling into the back of it first, then you clamp some mole grips onto the tool and it brings out the bolt with it. It may have been called a stud extractor, was about the size of a nail punch and it didn't cost much.

Good one, I recall something like that now you've said cheers

[Pieoftheday]

Depending on the size of the head (and whether you have a steady hand) might be worth trying to hacksaw a groove across the diameter and then use a screwdriver. Have done this before with some success. My experience with drilling out bolts is that I usually swear a lot and bugger up the existing screw thread either way.

Cheers Mike, unfortunately access to the bolt makes that impossible

[Ian7633]

I think this is the tool that Steve was talking about.

https://www.ebay.co.uk/itm/5-Screw-Extractor-Set-Drill-Bits-Easy-Out-Guide-Broken-Damag-Screws-Bolt-Remover/253307033946?epid=1958040035&hash=item3afa46995a:g:ymUAAOSwCcZaLtyf

[Oddball]

Screw extractors are ok if you think the threads nice and loose but snap them off and its a world of hurt because then you have a hardened piece that you defo cannot drill out .
Any chance you could mig a nut onto the existing rounded off allen head ?

[CageyH]

If buying screw extractors, get decent ones because if you have one snap, you have a bigger problem.
If drilling stainless, I would suggest cobalt drills, use a slow drill speed and cutting lubricant.

You can't get a set of mole grips on the head?

Try soaking the bolt with a decent dismantling lubricant, like plus gas for a few days. Then try the mole grips.
Another way of getting the bolt out is to hammer a torx bit into the allen bolt, but I don't like doing this. It damages the tools.

[walpurgis]

Screw extractors can be useful, but can also snap off in the hole drilled for them, leaving you with an even bigger problem.

If you can't cut a slot for a screwdriver, I'd drill it out. Mark the spot to drill as centrally as possible with a dot punch, then drill with a small drill going to successively larger sizes. Once you've drilled wide enough, the remains of the bolt thread will probably fall apart and can be cleared out leaving the female thread hopefully intact. Don't drill too big a hole or you'll take the whole thread out and have to drill larger and tap a thread in.

I've done this loads of times. I used to rebuild cars and bikes.

[walpurgis]

I see somebody else has mentioned snapping screw extractors. :)

[Magna Audio]

Plenty of penetrating oil and cut a slot using a Dremel or similar cutting wheel. Can make as wide as slot as needed.
This method, scaled up, worked on a buggered Torx M10 bolt on a VW Passat half shaft but using a 1mm thick cutting disc on an angle grinder.
I then used a air hammer wrench with a slotted bit too extract said bolt.

[Pieoftheday]

Screw extractors are ok if you think the threads nice and loose but snap them off and its a world of hurt because then you have a hardened piece that you defo cannot drill out .
Any chance you could mig a nut onto the existing rounded off allen head ?

Mig? There's no way of gripping the outside of the bolt, smooth round shallow dome and the inner Allen recess has rounded off too much. A 10 minute job it should've been:steam:

[Pieoftheday]

If buying screw extractors, get decent ones because if you have one snap, you have a bigger problem.
If drilling stainless, I would suggest cobalt drills, use a slow drill speed and cutting lubricant.

You can't get a set of mole grips on the head?

Try soaking the bolt with a decent dismantling lubricant, like plus gas for a few days. Then try the mole grips.
Another way of getting the bolt out is to hammer a torx bit into the allen bolt, but I don't like doing this. It damages the tools.

Thanks for the suggestion of drill bit.i reckon it's the way I'll go as drilling the middle of the bolt worked well , though it was ages ago since I've done it.theres no way of gripping the bolt at all now the Allen recess has rounded off.:(

[Svend N]

If the allen hole still has a bit of original shape to it, not totally rounded off, you could try this stuff: http://www.screwgrab.eu

I've used it on many a stripped screw and allen head, and it's amazing stuff. Grips like a mad thing. Everyone's tool kit should have a little bottle of this.

Good luck!
Svend

[Pieoftheday]

If the allen hole still has a bit of original shape to it, not totally rounded off, you could try this stuff: http://www.screwgrab.eu

I've used it on many a stripped screw and allen head, and it's amazing stuff. Grips like a mad thing. Everyone's tool kit should have a little bottle of this.

Good luck!
Svend

Cheers Svend:)

[Pigmy Pony]

I think this is the tool that Steve was talking about.

https://www.ebay.co.uk/itm/5-Screw-Extractor-Set-Drill-Bits-Easy-Out-Guide-Broken-Damag-Screws-Bolt-Remover/253307033946?epid=1958040035&hash=item3afa46995a:g:ymUAAOSwCcZaLtyf

Cheers Ian, that's it exactly.

[Pigmy Pony]

If the allen hole still has a bit of original shape to it, not totally rounded off, you could try this stuff: http://www.screwgrab.eu

I've used it on many a stripped screw and allen head, and it's amazing stuff. Grips like a mad thing. Everyone's tool kit should have a little bottle of this.

Good luck!
Svend

Interesting stuff Svend, never come across that before.

[Svend N]

Steve, this stuff has saved me hours of aggravation trying to get stripped screws and allen bolts out. I now reach for this at the first sign of trouble. One small drop is all it takes. Highly recommended!

Edit: just checked, and it's available on Amazon UK for 6.50 gbp

[Pigmy Pony]

I think I can make room for it in my van. It can go on the "only need it 1% of the time, but when I do I need it 100%" shelf. :)

[Yatsushiro]

Assuming you haven't tried to drill the bolt yet, you could try a suitable size Torx bit, as pictured:

https://www.bhphotovideo.com/images/images2000x2000/Raxxess_PNTX_B_Pin_Torx_Bit_Star_143902.jpg

Tap it into the deformed Allen recess, then use a spanner or socket to undo the bolt.

[Len Co]

You probably can't do this if access is limited but filing some flats on the round head might work another time - don't think anyone has already suggested...

[Pieoftheday]

Assuming you haven't tried to drill the bolt yet, you could try a suitable size Torx bit, as pictured:

https://www.bhphotovideo.com/images/images2000x2000/Raxxess_PNTX_B_Pin_Torx_Bit_Star_143902.jpg

Tap it into the deformed Allen recess, then use a spanner or socket to undo the bolt.

Cheers Paul, tried one after the Allen head failed, I think the bolt must be a bit soft as it rounded of quite quickly

[Svend N]

I think I can make room for it in my van. It can go on the "only need it 1% of the time, but when I do I need it 100%" shelf. :)

One bottle should last decades, as you only use a drop at a time. Of course, it probably won't work if the screw head is totally rounded off...there should still be something for the wrench or driver to grip onto. But I use it as soon as a screw head starts rounding off to avoid further damage. Together with penetrating oil on the threads, you should be able to get most stuck screws and bolts out.

Let me know if you try it.