Nuovo record front derailleur - limit screw snapped

[wriggles]

Hi - I wonder if anyone has any ideas please? The limit screws on a nuovo record front mech has snapped - possibly because the screws have corroded into the alloy. All thats left is the stubs below, where the mech limits touch. Any ideas on how to get them out?

(Tried a soaking in plus gas and also pooring hot water on them)

Pic:

 

[Old Ned]

A very common problem with these mechs. I have 2 or 3 bodies like this including a very rare early one. I was going to mount them on a section of seat tubing in the jaws of a milling machine vice and drill them out - very carefully! I know this can be done as an acquiantance has had it done by an engineer friend of his but I haven't been able to ask who it was! However, I have several friends in the model engineering hobby with the correct equipment who may be able to do it. I just need to get on with it!

 

[wriggles]

Yeah this is c.1962/3 so worth the saving I think.... I'm looking for a solution that avoids drilling first though

 

[Old Ned]

Sadly I don't think there is one.

 

[gtRTSdh]

Have you tried grabbing whats left with pliersand having a good go both ways?

 

[wriggles]

Yeah tried that with a normal pair of relatively fine nose. There isn't a micro molegrip out there somewhere is there?

 

[gtRTSdh]

http://www.ebay.co.uk/itm/Irwin-Vise-Gr ... 256e9b7947

Or any could be ground to suit.

 

[wriggles]

If it was a bottom bracket i'd have the blow tourch on it. Wonder how much heat it can take?
Edit: liking those molegrip badboys! But suspect too big...

 

[Ian Raleigh]

The best way to get that out is by the use of a Dremel type mini drill attached with a very small carbon cutting disc.
You need to cut slots into the threaded sections then try to unscrew them with a screwdriver.

The heat caused by the grinding will normally loosen the screws but If the slotted screws break off now is the time to
remove as much steel as you can with the carbon disc, then change the attachment and drill a small hole into the centre
of the screws, going up in the drill size until there is hardly any screw left, screw in a self tapping screw to remove the last bit of steel.

Both of my stop screws seized up and broke off and this was the only way my buggered screws could be removed.

 

[Old Ned]

remove as much steel as you can with the carbon disc, then change the attachment and drill a small hole into the centre
of the screws, going up in the drill size until there is hardly any screw left, screw in a self tapping screw to remove the last bit of steel.

I suppose this is basically what I was suggesting by using a milling machine or vertical drill. Using something hand held could lead to damage if it slips.

Trying to screw the remains out with grips etc. could probably just shear off the remaining bits. If they broke when using a screwdriver then I can't see anything else more brutal working. The adjusting screws are only made of mild steel so will corrode and rust easily if not heavily greased when fitted.