removing screw with stripped head from SJolly

[aselby99]

So, cleverclogs here tries to change his burrs. Concerned about the screws being flush where they fix the bottom burr in place I use a powerdriver. Carefully.

Well, except I spaz out for a moment on the last screw so it pretty much wears the crosshead away to a circle

I've heard about the BOA grabit removers, can get on Amazon, but just wondered if anyone had experience of them, or had any other suggestions about removing this screw when, manual driver or otherwise, I can't get any purchase on the head to start it twisting.

A lot of advice online is about getting screws out of flat surfaces, but given this is in a little flushed hole not a lot of it is relevant.

[lukas]

This sounds scary. Sorry, can' t really help you with this

[Gouezeri]

I've had this problem before... I bought a rocky that had a bottom burr with knackered screws (the full story/details are on the forum). On that occasion I managed to drill it out (you need a bit marginally smaller than the diameter of the screw, and very steady hands, or a lot of luck... on that occasion, I was graced with the latter, for once). That is a bit of a last measure though. I've also used a dremel in the past to create a new slot for a screwdriver to bite in.

Anyway, I'd start by using a reverse thread screw extractor. This is essentially a special drill bit which screws into the head of the stuck screw anti-clockwise, hopefully biting as it does, thus releasing the screw. I think maplin have sold these in the past, but I don't know if they currently do, B&Q didn't at the time I bought mine. Let me know if you have difficulty finding some and I'll see what I can find online for you. The only real trick is to start small and go gently as at this point, pretty much every option will be destructive in one manner or another. If you're really concerned about ballsing things up, try going to your local (decent) bike shop, they will have been confronted with this problem lots of times already, and will have the knowledge to help.
Give us a shout here if you need any more specific advice.
Cheers
D

[bruceb]

The problem with any reverse-thread is that they can break off and then you have a can of worms. The BOA extractors are probably the second best bet as they are unlikely to break. The best bet is a good machine shop. If they cannot get it out any other way they can drill it out, but if a broken left-hand thread is stuck in the screw that is almost impossible.

If you try to do it yourself make sure you soak it first with penetrating oil and if you can heat it that is even better. It is not a trivial problem on a machine that gets warm and cools repeatedly.

[Gouezeri]

I can't remember what my reverse thread screw extractors are made of, but it is pretty damn strong stuff (used one to remove a rusted in crank bolt in a bottom bracket). In fact they don't look that similar to the BOA's on amazon, more like a normal screw bit then a reverse thread.

If I read the OP correctly, he possibly overtightened it when re-installing his burrs? In which case, the screw is probably not seized (a blessing in itself) so it shouldn't need penetrating oil (tho it wouldn't hurt, provided you don't use too much and it is food safe). I would advise against spraying liberally with WD40 and then shoving a blow torch on it

I think what Bruce and I are both saying is, this isn't really that much of a problem, provide you have an idea of what you are doing and proceed with caution. Getting somebody else to fix it, with experience of this kind of thing, is probably best if you're uncertain.

[bruceb]

Dom, the problem as I see it here is that this is a very small diameter screw and consequently, the reverse thread has to be still smaller. When they get down into the millimeter size it is very easy to break them. The grabit extractors are also reverse thread, but rather than being a thin screw-like device they are more rounded and dig into the head of the screw. They come with a "reamer" that prepares the head for removal. As you said, however, proceeding with caution and having experience in their use are probably the most important prerequisites. It's easy to make a big problem out of a smaller one by rushing into it.

If you use penetrating oil it is good to wash the part after successful removal with a neutral solvent and then with alcohol, or if it can be washed in water and detergent, then dried in an oven for a few minutes you're safest. WD40 leaves a nasty aftertaste.

[Skippy]

I think id agree with the advice of finding a machine shop to do it for you, messing something up could cause much bigger problems.

[aselby99]

thanks to all for replying back. is there such a thing as 'machine shop' in the yellow pages?

i'm half inclined to have a go with the grabit though the diameters are quite tight.

guess it depends on what someone at a 'machine shop' wants to charge...as ever.

cheers
adrian

[triptogenetica]

A bit late coming to this -

but when I stripped a screw head removing the old burrs on my BB105 (big Bezzera grinder), I did the following:

- swear a lot
- spray around the screw head liberally with GT85 (like WD40)
- go away for the weekend and forget it
- come back
- dremel the screw face a bit to make it into a slot again
- big screwdriver in the slot, pushing vertically down, turn..

- and it comes loose!

I think the GT85 was the secret.

[GreenBean]

A bit late coming to this -

but when I stripped a screw head removing the old burrs on my BB105 (big Bezzera grinder), I did the following:

- swear a lot
- spray around the screw head liberally with GT85 (like WD40)
- go away for the weekend and forget it
- come back
- dremel the screw face a bit to make it into a slot again
- big screwdriver in the slot, pushing vertically down, turn..

- and it comes loose!

I think the GT85 was the secret.

I have always found that swearing a lot helps more than anything else.

[JankSolid]

I've had a lot of success with this method:

- Carefully drill a hole down the centre of the screw.
- Tap a small Torx bit in to the hole, keeping it straight, until it's in there nice and tight.
- Back the whole lot out with an electric screwdriver or drill.

[CakeBoy]

Great advice. Welcome to TMC JankSolid

[z3t4]

- Carefully drill a hole down the centre of the screw.
- Tap a small Torx bit in to the hole, keeping it straight, until it's in there nice and tight.
- Back the whole lot out with an electric screwdriver or drill.

^^^ WHS^^^
To echo some more points from the thread:

Change the mashed-up irregular hole into a smooth dish or cone, probably by using a Dremel or less-overpriced equivalent. This will reduce the chances of snapping the drill when you drill the pilot hole.

Screw extractors work well but the small ones snap easily. Use a leccy driver on a v low torque setting in reverse.

Draper Expert 45856 are nice, IME.

HTH,