grub screw

Hi, After six succesful ones, I did it again... What is the way to remove a M2x4 unslitted grub screw from a locked up brass ring? No EDM yet.
Tia, Dirk
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A solution in water of potassium alumium sulphate, commonly known as alum, will dissolve the steel without affecting the brass.
Cliff Coggin.

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How long will it take Cliff? I tried the equivalent of sulphuric acid to get a piece of 3mm drill out of Aluminium and gave up after a long weekends worth of messing about.
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It depends how warm it is, how often you replenish the alum as it is exhausted, how well you de-grease the screw, etc. but about a day should do it.
Cliff.
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Cliff, can this "alum" by accident be found in fertiliser? Dirk
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I don't know about fertiliser, but it is used to turn change the colour of pink hydrangea to blue.
Cliff.
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wrote:

Or you could try a carbide drill, rigid setup, drill at af size plenty of coolant so you drill the centre of the screw out, then you have a chance with a square tapered punch in the hole and turning or just collapse the remains of the screw. Peter
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