# Square hole drill



## hamishb (Oct 23, 2008)

This us an interesting video, clever orientals.
www.youtube.com/watch?v=ALiqAXiTQBg
Hamish


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## Derek Roger (Feb 19, 2005)

Good Grief what next ? A lathe for turning square pegs no doubt .


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## uisdean mor (Sep 4, 2008)

Ah Hamish 
what you might describe as a rotary shaping machine. Clever - would like to see the tolerances on the machine after some heavy steel work and not just the aluminium milling.
Rgds 
Uisdean


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## Pat Kennedy (Apr 14, 2007)

Its not a new concept, its called the Harry Watt drill bit and was patented by the said Harry Watt in 1914.
My Uncle Jack who was a model boat builder, had one in the 1950s and I remember watching him use it to drill the opening for the engine room skylight on a model of a Cunard ship he was constructing in his garage.
Its based on a shape called a Reuleux triangle which is similar to the Wankel rotary engine shape.
There is a good explanatory animation at this link;
http://mathworld.wolfram.com/ReuleauxTriangle.html

Regards, 
Pat


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## Jocko (Oct 31, 2011)

Your correct Pat, I remember this being done on the Milling machines when I served my apprenticeship in the mid 1950s. Don`t give the Chinese all the credit, our Victorian engineers were brilliant.


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## Shipbuilder (Jun 30, 2005)

They drilled square holes in wooden railway sleepers in the days when they used wooden ones. It was fairly simple. A round drill went through the sleeper first, closely followed by a fixed square cutter that just cut the corners! I would be very interested to hear if there is a method of drilling small oval holes in thin metal sheet. Bit laborious drilling a round one and then filing it oval!
Bob


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