Just saw this in reddit... thought you guys might find it interesting!
http://hugelolcdn.com/i/89696.gif
http://hugelolcdn.com/i/89696.gif
Square Hole Drill Bit
- Thread starter Don AJ
- Start date
Steven67fr
Well-known member
Neat visualization - seems like they'd need one more point of stabilization along the actual bit.
chrisa7164
Well-known member
looks like a Mazda engine.
DieselSaves
Well-known member
Saw a design for a square hole drill in an old blacksmithing book, something like The Art of Blacksmithing. The old ones required a set of rollers that allowed the work to move under the bit. I'll see if I can find the right book.
ddawg16
Well-known member
But it's not really square...the corners are round......
Come on....someone had to point that out....
Come on....someone had to point that out....
IIRC it is called a Watts drill, based upon the reuleaux triangle. Neat and really cool for blind square holes. Don't plan on going to your local HD or Lowes to purchase one. 
I have one that was hand built by the master tool and die maker that taught me machining. I can count on one hand how many times I have used it.
BTW, they also make them for other flat sided shapes, like hexagons.
I have one that was hand built by the master tool and die maker that taught me machining. I can count on one hand how many times I have used it.BTW, they also make them for other flat sided shapes, like hexagons.
Last edited:
donthelegend
Well-known member
I have no idea what the hell I would do with one... But that is damn cool, and I want one 
theoldwizard1
Well-known member
Its call rotary broaching. Besides square they can do hex and Torx.
Watch this video and they show EXTERNAL rotary broaching !
Watch this video and they show EXTERNAL rotary broaching !
That is actually a different process than the watts type drill that the OP posted. The cutting action is quite different (straight cut broaching vs rotating drill type). The rotary broaching will produce sharp corners unlike the drilling technique as ddawg pointed out.
I'll have to do a search, but IIRC a few, quite a few years back one of the machinist magazines put out plans to make a watts drill at home. I just don't remember who or where.
Side note, interesting link, I met a few guys from McGill, they have a good team and are very friendly folks.
