removing small grub screws

[plumber89]

hi there got to service a shower valve , but to remove it i need to take the head off but it is held on with a small grub screw ( probably about 3-4mm in diamete)
only thing is this is rounded and i cant remove with allen key /torx/ tright flat head screw driver etc

has anyone heard of a a screw/stud extractor small enough? or how they work cheers? my only option othrwise is to drill it out but i will ruin the fitting

thanks

 

[MattWeth]

I'd say carefully drilling it out is your only option.
Carefuly centre punch the screw and drill it out probably starting with a 2mm drill working slowly up in sizes until you're near the threads. Then use a small angled pick to remove what's left of the screw. I've done this loads of times on various fixings on old motorbikes etc, but never on a shower valve 🙂

Don't bother with a screw extractor - they're the tool of the devil.

 

[Pipes Plumbing]

Can you get a needle file in there to cut a slot across the top at either side so you can get a flat screwdriver in there?
5 minutes of filing might be an option if you're not comfy drilling it

 

[plumber89]

no room for a file or anything the grub screw is about 3-4 mm and the hole is prob 5 at most

"why are screw extractors a tool of the devil?"
cheers

 

[Osp]

MattWeth no doubt has his own reasons but I think they're the devil's work because

a) they very rarely work

b) they are brittle and snap off in the hole leaving a piece of hardened steel in there that prevents you from drilling or using any other method of extraction

c) the fact that you now have to buy a whole new unit loads up the swear box so you are doubly skint

 

[MattWeth]

MattWeth no doubt has his own reasons but I think they're the devil's work because

a) they very rarely work

b) they are brittle and snap off in the hole leaving a piece of hardened steel in there that prevents you from drilling or using any other method of extraction

c) the fact that you now have to buy a whole new unit loads up the swear box so you are doubly skint

Spot on.

Especially points a & b.
Even if you could find a screw extractor small enough to get into your problem grub screw, it would be so fine and brittle that it would be almost guaranteed to snap. When I was young and stupid(er) I snapped off a screw extractor in the cylinder head of a motorbike. This lead to an expensive appointment with an engineering firm and their spark erosion machine because as Osp rightly points out, screw extractors are made from hardened steel that's impossible to conventionally drill out.

As before, I'd either carefully drill it out (brass is soft and drills easily), or perhaps use a dremmel if you have a fine enough tool to get in there.