Malcolm,
 
Does the H. Mueller spiral tool accept standard bitstock tools, or are those
smaller than what would be used with a common brace?
 
If they are standard, I am surprised that the tool never "caught on", as it
seems just about ideal for use with a countersink or a bitstock-headed twist
drill.
 
Then again, for all I know, H. Mueller tools might be common in Australia.
 
John Ruth 
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