Drill square holes in metal?

I drill triangular holes.

Ok, I'll be your Huckleberry.

How?

I don't know why, it just happens.

Your video link is outside my reach, but maybe the drill is really a broach?

We've all seen triangular holes from standard jobber bits. The bit flexes a little while drilling causing the hole to resemble a Reuleaux triangle.

--Winston

I don't think so....

From the Reuleaux Triangle link you posted, "Because it can be rotated inside a square, as illustrated above, it is the basis for the Harry Watt square drill bit."

yeahbut...

I still think it implies a gearbox inside the drill bit.

I don't think that's the deal here, Winston. It's making nice square holes, albeit with radiused corners.

the few brain cells I have left are complaining madly about that.

A 3-tooth gearwheel on the drill chuck, engaging the inside of a stationary (fixed) 4-tooth inside gear.

The drill motor in this instance only makes the drill "orbit"--the motor does not spin the drill directly, the gear engagement does that.

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Now MY question is,,,,, can you drill different-sized holes with one of these setups? Or is each head just fixed to use one bit, to make one size?,,,,

If it was adjustable at all, I'd think the range would need to be kept pretty small. Like maybe 1/4-inch to 1/2-inch?

-Unless the whole thing is not just CNC, with servos controlling the motions. Which I think would be more likely with a modern setup. That way you could drill holes with any number of corners you wanted, down to three corners....

Check these out too:

Watch the collet area REAL close. Notice that it has LOT of motion.

shows how it works.

(...)

I was addressing your 'Huckleberry' question about the triangular holes. The two are related. The cutters in both cases oscillate as well as rotate. In the 'jobber drill' instance, the oscillation occurs as the long, spindly bit ricochets around the center, bouncing off the walls of the hole.

The square cutter does have a gearbox to carefully control the additional displacement of the cutter to create a square hole. See how:

--Winston

Doesn't Mazda use those?

-- Worry is a misuse of imagination. -- Dan Zadra

I think you are stretching it by trying to call a cam inside a box guide a "gear box". :)

This link is interesting:

It shows that with a slightly different shape, you can make it trace a true square instead of one with rounded corners. But the drawback, is that only one point is tracing the square, instead of three, so you could only have one cutting edge using that technique.

The original link on this thread seems to be cutting corners that are more square than a standard Harry James Watts Reuleaux triangle drill.

If you look at the drill at the opening of the video it looks far more triangular with flatter sides and truncated corners so maybe they figured out yet another cam shape that does a better job? The noise it makes when drilling however makes it sound like it's a box cam flapping around so it doesn't look like they used special gears to do the work.

(...)

Should I have said 'gear in a box'? :)

Yes but still less time in handwork to sharpen up the corners if that is necessary.

Very cool. Thanks!

--Winston