How can these screws be removed from boiler?

[Jon]

Hi,

I've inherited a Glow worm Micron 50FF boiler and the two hardened, self tapping screws which hold the combustion chamber cover on are completely ceased, refuse to move and are rounded off nicely.

?image=boiler2bn0.pnghttp://img396.imageshack.us/my.php?image=boiler3wy4.pngThe trouble is they are in a recess so I can't get in there with a hack saw and cut a groove into them. I've also tried using a set of damaged screw remover drill bit things, but all they do is round them off more. Drilling also does nothing as they're hardened.

Has anyone got any ideas about how to remove these screws so I can hoover out the burner? I suspect that even though the boiler was serviced before we moved in 18 months ago as we have the cert', I doubt it's really had one for some time as the man from Grittish Bas wouldn't have been able to get these screws out either. I want to get my heating running as efficient as possible with all these bloody gas price hikes!

Many thanks,

Jon

[Kevin]

a dremmel style drill and a little cutting disk these will cut through hardened steel with no problem

[dennis]

A narrow cutting disk in a drill, angle grinder or dremel to make a slot and use an ordinary screwdriver.

[Harry Bloomfield]

The fact that they have rounded off, indicates that they are not very hard. There is no sign of rust so I would doubt they had seized in.

Are you sure you have used the correct type/size of screw driver?

Could they be Torque or star heads? Have you tried hitting a suitable screw driver with a hammer to help loosen them?

Have you tried an Impact driver?

If all else fails, a very thin cutting disk in a grinder would cut a slot in the head.

[The Medway Handyman]

Cobalt drill bit will take them out. 'Proper' tool shops sell them.

[Jon]

There is no correct type/size of screwdriver for a rounded screw is there? The screws were knackered by a BG engineer doing a service some time in the past I suspect, and walked away from it when he couldn't get them out. Nice one.

Pretty standard posi-drive from what was left of them. Have tried the hammer thing. No difference.

The screw heads are rounded. How would an impact driver's bit bite onto a rounded head?

This is all that's left I believe. I will try and get a disk today and cut a groove.

Thanks everyone for your replies.

[Cicero]

================================== These screws are almost certainly 'self tapper' type screws. I would suggest that you start by inserting a thin flat screwdriver between the inner and outer layers of steel plate just sufficiently to open a gap to enable you to squirt in some releasing oil.

Then get a pair of 'bent nose pliers' (like these but may be available locally:

) and grip the threaded tip of each screw by reaching behind its housing. Once you have started each screw moving it will probably be only finger-tight and removable quite easily.

Cic.

[Jon]

Brilliant! Thanks, I'll give this a go.

[Clint Sharp]

In message , Jon writes

If you've not used the disk yet, could I suggest a pair of side cutters (something like item 2

) nipping the head of the screw and as close to the correct size driver as you can approximate, pushing hard with the driver and turning both together will often work.

[Dave]

Using a Cobalt drill of about 2.5 to 3 mm, on a very slow speed, with good pressure applied at the rear of the electric drill body, so that the pressure is in line with the twist drill. Put no pressure on the drill handle other than to squeeze the trigger. This will prevent you bending and snapping the twist drill. After this, you should be able to move onto a standard HSS drill bit, of a larger size until you drill off the head of the screw. If the screws are removed by this method, then you have entered into another problem. The panel does not look thick enough to let you get any mole type grips on the screws. You may have to drill 2 new holes to screw the panel back on. You could drill right the way through the screw and change it for the next size up, just don't use the same size drill that you used to drill the head off until you can determine what size drill to use. Another tip is to find a length of tubing that will fit over the twist drill that will enable you to limit the depth that the drill can cut. You will never know what is behind the screws. Use the chuck to set how much twist drill sticks out of the end of the tube. It will prevent you drilling into something that could prove expensive to replace.

If you go for the cutting of a slot, Make sure that you try to remove the screws just after the boiler has fired and as soon as it shuts down.

Dave

[Jon]

Got the two mangled screws out with the aid of a set of mole grips.

Thanks everyone for your help.

Jon