Got a Stihl hedgecutter and a couple of very hard bolts have sheared off. Problem is the remnants are in some very soft alloy so the bolts would need to be very carefully removed.

what size are the bolts?
one option is (depending on size) to drill out at a safe distance from the threads, as in drill bit smaller than bolt dia. by 1 or 2 mm, then find something to ram in that new hole to a tight fit and see if it will loosen

if bolt is proud of casing, can always make a screwdriver slot with a hacksaw

Bolts are quite small M5 at a guess. Neighbour who is a retired engineer reckons it’ll be very risky to do. Unfurtunately there is none of the bolts showing.

mm
can try local engineering shop (if there are any left)

easyouts (drill into bolt. screw in easy out – reverse thread so should screw out bolt)

I have (on a motorbike) drilled the bolt out as close as I dared and then using a very small pick slowly peeled the the bolt thread out of the hole – mind you I was sweating a lot ……..

could you drill in a hole and araldite a allan key etc into the hole ?? (ps I really do think that proper araldite is that good)

Easyouts + 1

Avoid easy outs if you can – if you snap them off which is all to easy with a small bolt then they never come out. If you do use them be very careful – if the bolt is corroded in don’t put too much pressure on the easy out.

Can you get access to a pillar drill? Makes it much easier to drill them out

if its the engine and iam assuming its the engine if its out of the hedgecutter and its not that hard to take them things to bits put the offending part in the oven to warm it up then try unscrewing the offending bolt by digging a screwdriver into the top of it or drill a small hole into it before you warm it and use an easyout.

i use to work in a plant hire place and we use to do about 3/4 of them a week in the same way

Do not try easiouts, they are tapered and although they will work when some of the broken bolt is showing they just tend to splay the bolt and tighten it into the thread. Drill a 2 or 3 mm hole and then gently tap an allen key into the hole, use the corresponding size key to the hole you have drilled. The allen key will act like a broach and cut itself into the bolt enabling you to unscrew it.

Or similarly to the allen key approach, try using a torx key. Grippier.

Thanks for the advice, my neighbour is going to have a go at it so I’ll wait and see how he gets on. He used to work in the workshops of the local mines and used to do this sort of thing all the time. I think he’s looking forward to the challenge

As above a torx socket on the end of an impact screwdriver, set direction then tap with a hammer the impact turns the head and the bolt loosens if your lucky. A 5mm bolt standard thread has a 0.8 pitch. If your neighbour drills it out bigger than 4.2mm he will remove the thread. If that happens tap it 6mm if poss using a 5mm tapping drill.

As above easi outs are a waste of time and money.