Square Hole Drills

[Jeff Wisnia]

Anybody know a source other than Watts Brothers in Pennsylvania that sells square hole drills?

Jeff

[Duane Bozarth]

I'm assuming you're talking of a mortising chisel? If not, I'm not sure what you're asking about.

[Edwin Pawlowski]

I'm not sure what you mean by square hole drills. I do know about mortise drills that are readily available at any woodworking supply. Same thing or similar?

[Jeff Wisnia]

No, I mean polygon drills, they've been around since the 19th century.

Here's a Brit company that sells them:

and a link to a Brit's hobby page showing one in use.

Jeff

[John McGaw]

Interesting. It does make me feel better about my own sanity that what is being described is not a "square drill" but an entire system including special floating chuck and guide plate that does the job. When I first tried thinking about the concept of a "square drill" it was about as easy to accept as "honest politician".

[Edwin Pawlowski]

Thanks for the links. I've never seen anything like that. You may find an answer at one of the woodworking or metalcrafting newsgroups. I've never seen them in a woodworking catalog or general tool catalog.

[Harry K]

Same here. I saw the title, says to self - must mean mortising chisel. Rethink and decide to read it anyhow as I just might learn something. I did.

Harry K

[larry]

machinist 101. I've collected many $5 bills with that bet. drilling a square hole with a twist drill in the drill press! and no arbor either.

unless someone gives it away, it'll cost you $5 before i prove it ;-) (over they years, I've also taken pity and gave the $5 back to the young kids just getting started, but it does make them better machinists)

-larry / dallas

[Harry K]

Ah yes, I know about that one.

Harry K

[Rich]

Fold a piece of paper in two put it between two pieces of stock and drill the hole half the depth of the drills width! Take the paper out unfold it an VIOLA a square hole. That'll be $2.50, weren't counting on competition were you Larry? LOL

Rich

[David Martel]

Larry,

I'm confused by this. What I see looks like a variation on the router bit and template sort of thing that is common in woodworking. Such tools make holes that are "mostly" square but the corners are not crisp 90 deg. angles, they are rounded. One finishes them with a chisel. How does this "polygonal" drill achieve good corners?

Dave M.

[kevin]

This is like the wierdest drill application I've seen in a while, but it's pretty obvious if you look at the page. Specifically, the bit about the floating chuck. The drill bit is is sort of sharpened triangule (three flutes, three cutting edges), but is allowed to wobble (float) so that it is not held aligned with the rotation. As it rotates, one cutting edge bangs into a corner of the metal template, the other two edges swing around a quarter turn making a cut, until the next cutting edge bangs into its corner. Just following the cutting edge is a big lump, that acts as a sort of cam, or lever, so that as the bit rotates, the bit floats from center and the opposite cutting edge actually travels in a straight line, rather than an arc. You get perfectly sharp corners, and can do this with any polygon with 4 sides or more (each needs a bit with N-1 flutes, and a metal guide piece, together with the floating chuck).

That's just about the worst explanation ever. You will have to look at the picture, especially the showing the bit in a square frame.

[spamTHISbrp]

Rotating chisel is a much better mindset for looking at it.

I wonder if you'd get a good edge if you came up with a mechanical setup that would move the bit as though it were striking the guide? Kinda like what drives the beaters in a big industrial mixer. Startup would be a problem, but there are ways around that....

-Dave

[Jeff Wisnia]

I'd hadn't heard that one before, but I presume that you place the paper between the two pieces of stock so that the folded edge of the paper and the edges of the stock are all coplanar, center the drill over the the folded paper edge and drill away.

What I don't understand is that Larry called it a "twist drill", which evokes an image of a typical angled drill point, and I don't see how that will result in a square hole in the paper. That'd give you a an irregular six sided hole, wouldn't it?

Seems to me you'd need to sharpen the drill with a flat end, sort of like an end mill to make the hole in the paper come out square.

Comments awaited,

Jeff

[Goedjn]

Or sharpen it to 45 degrees, and don't drill past the cone.

[Jeff Wisnia]

Good reply!

Jeff

[larry]

flattening the end of the twist drill on grinder is first step.

paper is correct,

two blocks are correct.

most pay off with just the description, but a few are happy to see the show for their money.

don't tell anyone else, i still need the money for my retirement!

another of my favorite sayings for the near impossible tasks-

"that's about as easy as lighting a match on a wet bar of soap" -still waiting for someone to prove it can be done, rules- paper match, regular bath bar soap. (barn burner on dry lava hand soap won't work either ;-)

have fun, we're only here once.

-larry / dallas