Came across this, looks neat!

 

hi Max,
Have you ever watched on TV, 'This Old at House', presented by 'Norm'.?
E

 

hi Max,
Have you ever watched on TV, 'This Old at House', presented by 'Norm'.?
E

Many moons ago. !

 

hi Max,
Those square hole drilling bits were used to build the 'Arc'.

E

 

hi Max,
Those square hole drilling bits were used to build the 'Arc'.

I must have missed that boat!

(Youtube Vid only 2yrs old)?

 

Rotary broaching is a method of making square (Or other polygon shapes.) holes. Here is a link that describes this method.
https://www.polygonsolutions.com/how-rotary-broaching-works/

Les.

 

You can drill a square hole with a three sided drill

 

You can drill a square hole with a three sided drill

It really depends on one's definition of "square" since most people don't think a square hole needs to have the radius of the corners defined.

 

It really depends on one's definition of "square" since most people don't think a square hole needs to have the radius of the corners defined.

The video on utube shows the real square hole
it was just I know some don't like running u tube videos, so I included the simple link to the theory

Check it out,
you would not believe the racket the floating drill make
you can do same with a simple triangle drill by hand ,
your hand performs the orbit

I've seen it done in wood, but never in a hard metal,

 

This does not seem to suffer that,?

Looks perfect and quiet.

 

I have one of those morticing attachments that belonged to my great granddad, he was a cabinent maker and died in 1963, and it was old then. The square part is made by a square chisel with the auger bit running down the center. So while it may be deemed a square hole drill, it actually only drills the round hole then the chisel makes it square.