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Drilling a Square Hole (with a rotating bit)

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Re: Drilling a Square Hole (with a rotating bit)

#2

Post by jacquesm »

There used to be one of these in my toolbox:

http://www.machinemart.co.uk/images/library/range/large/0104...

The small remaining bits at the corners were pushed out by the pointed segments by feeding the bits of leftover wood into the rotating bit.

Worked wonderfully, I wonder during which move i managed to lose it, I always thought it to be a pretty ingenious device.

Mathematically not as clever as the one in the article but definitely simpler and it did the job.

Re: Drilling a Square Hole (with a rotating bit)

#5

Post by lucifer »

chime wrote: post #3

I wonder if the unsolved problem of drilling a triangle hole is related to the geometric problem of dividing a line into three equal parts with just a compass.

You can't trisect an arc using only a compass and a straightedge. (You can simulate a straightedge using a compass.) Dividing a line into 3 parts is trivial.

Re: Drilling a Square Hole (with a rotating bit)

#7

Post by PonyGumbo »

jacquesm wrote: post #2

There used to be one of these in my toolbox: http://www.machinemart.co.uk/images/library/range/large/0104... The small remaining bits at the corners were pushed out by the pointed segments by feeding the bits of leftover wood into the rotating bit. Worked wonderfully, I wonder during which move i managed to lose it, I always thought it to be a pretty ingenious device. Mathematically not as clever as the one in the ar…

I've been pleasantly surprised at how often I get to use my bench-top mortising machine for projects outside of mortise and tenon work.

Re: Drilling a Square Hole (with a rotating bit)

#8

Post by giardini »

jacquesm wrote: post #2

There used to be one of these in my toolbox: http://www.machinemart.co.uk/images/library/range/large/0104... The small remaining bits at the corners were pushed out by the pointed segments by feeding the bits of leftover wood into the rotating bit. Worked wonderfully, I wonder during which move i managed to lose it, I always thought it to be a pretty ingenious device. Mathematically not as clever as the one in the ar…

Thanks, found it! It's a "mortise chisel and drill": a much more practical solution that I can buy!

While the Reuleaux concept is mathematically cute, it isn't very practical and is only approximate. And the Reuleaux bit requires a special chuck to ensure that the square is "upright" (not tipped at some arbitrary angle): http://upper.us.edu/faculty/smith/reuleaux.htm for details.

There's a joke in this somewhere about mathematicians and carpenters.

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