Drilling a Square Hole (with a rotating bit) • Hacker News Board

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

#11

Post by iguanatom » Tue, Sep 01, 2009, 4:05 PM UTC

bcl wrote: post #10

Am I missing something? The holes can't be square, because of the rotating motion required to create them they will always have rounded corners. I'd like to see pictures of the holes created with this bit.

You are right, it's not really square, but the rounded edges can be chiseled away fairly easy, especially if the drill bit has the chisel built right into it as jacquesm's earlier image showed (http://www.machinemart.co.uk/images/library/range/large/0104...). although if it's hard wood, you may need to use a solid chisel and a hammer to pound the heck out if it.

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

#12

Post by jrockway » Tue, Sep 01, 2009, 5:06 PM UTC

riffic wrote: post #6

a man in china invented a bike with non-circular wheels http://technology.timesonline.co.uk/tol/news/tech_and_web/ar... http://www.china.org.cn/china/photos/2009-05/07/content_1773...

Amusing: "He believes that people will be drawn to the bike because it requires more work to cycle and therefore will provide more exercise for the cyclist than a conventional bike."

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

#13

Post by misterbwong » Tue, Sep 01, 2009, 5:09 PM UTC

uuilly wrote: post #9

Here is an animation showing how it works: http://upload.wikimedia.org/wikipedia/en/2/20/Rouleaux_trian...

The link above is an animation of the Rouleaux Triangle and will draw a square with rounded corners. In this article, the author talks about a variant of that triangle that will draw exact squares.

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

#14

Post by roundsquare » Tue, Sep 01, 2009, 5:15 PM UTC

Ok, given my login name, I feel like I have to comment on this article.

Also, here is a video of this in action. http://www.youtube.com/watch?v=9qEhyQfbImY

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

#15

Post by silentOpen » Tue, Sep 01, 2009, 5:16 PM UTC

uuilly wrote: post #9

Here is an animation showing how it works: http://upload.wikimedia.org/wikipedia/en/2/20/Rouleaux_trian...

That's only the Rouleaux bit. The article details a bit that produces sharp (vs. rounded) squares.

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

#16

Post by brunoc » Tue, Sep 01, 2009, 5:23 PM UTC

Rounded corners.. giving problems to engineers for 100+ years. :)

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

#17

Post by fishercs » Tue, Sep 01, 2009, 8:09 PM UTC

rotary engines.

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

#18

Post by sp332 » Tue, Sep 01, 2009, 9:27 PM UTC

lucifer wrote: post #5

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.

Funny I'd forgotten that that was possible. http://upload.wikimedia.org/wikipedia/en/d/dc/Trisectsegment...

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

#19

Post by ianferrel » Tue, Sep 01, 2009, 10:01 PM UTC

bcl wrote: post #10

Am I missing something? The holes can't be square, because of the rotating motion required to create them they will always have rounded corners. I'd like to see pictures of the holes created with this bit.

That's what I thought, too, but then I realized that what we were both missing is that the edges of the cutting surface are not the same as the edges of the shape.

The vertices really do trace out a right angled square, so if you just put cutting surfaces at the vertices and inside them, it really will cut a square.

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

#20

Post by uuilly » Wed, Sep 02, 2009, 12:26 AM UTC

silentOpen wrote: post #15

uuilly wrote: post #9

Here is an animation showing how it works: http://upload.wikimedia.org/wikipedia/en/2/20/Rouleaux_trian...

That's only the Rouleaux bit. The article details a bit that produces sharp (vs. rounded) squares.

It was confusing b/c the pictures didn't show that the bit's axel had to orbit independently of the bit. This animation cleared that up for me even if it wasn't the exact case.