# Would you like to drill a square hole?



## afinegan (Jan 2, 2008)

I just saw this online, very cool.


http://www.geekologie.com/2011/10/m...lls-sq.php


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## Greg Elmassian (Jan 3, 2008)

Yep, looks like there is a gear mechanism inside that does the "offset" motion... reminds me of the offset motion of the rotor in a Wankle engine. 

Note it does not "drill" a square hole, but it "mills" out an existing round hole to a square one. Also, see if you notice the specs in the video, looks like 5 mm per minute feed rate, pretty slow... but again, a cool and unique product. 

Greg


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## Totalwrecker (Feb 26, 2009)

In the opening segments under the Chinese characters is the fine print; Corner Mill 
Kinda neat tho' 
John


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## Gary Armitstead (Jan 2, 2008)

Because I used to program and operate NC mills, the scary part to me is seeing the "wobble" in the tool. If I saw that, I would be thinking the cutter had not been taken into the holder properly during a tool change and that thing was hanging on by a thread! That is pretty cool though. I wonder what the accuracy is on the hole? I've got to read up on that. Eight years out of the trade and big changes and inovations.


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## Greg Elmassian (Jan 3, 2008)

The "wobble" is the trick to how it works. It must be geared inside. 

Greg


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## Gary Armitstead (Jan 2, 2008)

Posted By Greg Elmassian on 14 Oct 2011 12:04 PM 
The "wobble" is the trick to how it works. It must be geared inside. 

Greg 

I KNOW the "wobble" is the trick. I'm not so sure it is a gear inside. I believe it might be a "cam" of some sort to hold the tolerance of the "wobble". I don't believe a gear can hold tolerances down to half a thousandth or even .002 or .003". There are many heads available as add-ons for jobs like this.


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## Semper Vaporo (Jan 2, 2008)

I broke the cheap plastic handle on my recliner and decided to replace the handle (cheaper than replacing the chair) and I had some 1.25x1.5 inch aluminium "bars". I turned most of a 10-inch long bar to be round as the "handle" end and left the square end for the place to attach to the axle that the old handle fit. That axle is a "square" steel tube, about 5/8-inch on a side.

I googled "drill a square hole" and learned about these drill "bits"... there is no end to the shape of hole you can drill, once you understand how they work. Some can drill the hole while they make it square, but most are more of a reaming action to form the square corners in a pre-drilled hole. The bit is triangular in shape, but with the peaks of the triangle pushed over to be a cutting edge. The center of rotation of that triangle is moving in a circle in the opposite direction to the spin of the triangle.

Really nice, BUT they were way too expensive for me.

I ended up chain drilling the edges of the hole with a bit that would leave the corners with the smallest radius I could accept, then drilling out the corners with a bigger bit offset to the inside so the larger bit did not overlap the sides of the hole I wanted. And then I drilled one large hole in the middle to remove most of the rest of the "hole". I then broached the sides smooth and straight. Took a long time, but worked very well.

UNFORTUNATELY... I wanted the hole at a slight angle in the axis of the handle so it would stick out slightly from the side of the chair, and in my mental gymnastics of figuring out what size hole to drill where, I got the angle wrong (the handle was tipped tighter against the side of the chair) and I had to use aluminalloy to fill the hole and do it all over again. Took just as long to do it the 2nd time!

That handle has now been on 3 different easy chairs and has fit every one of them!


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## rkapuaala (Jan 3, 2008)

too cool.


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