How does a mortising machine work?

[JKimel]

Kinda of like a hammer drill except with a mortising bit? A regular drill bit with a square chisel around it in a sense?

[Rob Young]

Modern machines use a bit more correctly called an anger than a drill bit.

Spur and cutting edge with large flutes to eject chips.

[Bill_de]

Rob Young said:

---

Modern machines use a bit more correctly called an anger than a drill bit.

Spur and cutting edge with large flutes to eject chips.

---

Or to be even more correct, we might call it an auger.

But drill bit gets the point across.

The drill/auger removes most of the material, and the chisel squares and smoothes the mortise.

--

[Guest]

JKimel said:

---

Kinda of like ... A regular drill bit with a square chisel around it in a sense?

---

^ This.

There are several different kinds of mortising machines available today, but the most common ones have a hollow, square chisel with an auger bit that fits closely inside the hollow. The auger wastes out the bulk of the matereal and draws it up into the hollow chisel where it is ejected through a slot in the side of the chisel. The bottom edges of the square chisel are sharpe. They trim the sides of the hole cut by the auger square. Again, the waste trimmed away by the chisel is drawn up into the hollow by the auger and ejected. The result is a square hole. Several of these square holes are drilled side by side (and overlapping) to create a mortise.

HTH.

Hank

[JGrout]

JKimel said:

---

Kinda of like a hammer drill except with a mortising bit? A regular drill bit with a square chisel around it in a sense?

---

Mortising machines work in at least three ways.

in your case the solution is not a mortising machine at all but a plunge router and a window template

it is still a dubious solution for your cantilevered shelf

[Wild Turkey]

The bit drill the hole, then the "chisel" surrounding it cuts the corners out and makes it square. The machine forces the chisel down and spins the bit.

[BloomingtonMike]

I would classify this is the function of a hollow chisel mortiser.

Mortising machines come in various styles for sure.

[AHill]

The term "auger" usually refers to a bit with a lead screw that pulls the bit into the wood. The bits that accompany mortise chisels don't have the lead screw. They have the cutting tips and spurs. The rest of the bit is usually a non-cutting screw that ejects the chips. Looks like some augers, but minus the lead screw. The chisel part just removes what the drill bit didn't to make the hole square.

[WilliamHodge]

Don't forget oscillating chisel mortisers. When you press the foot pedal, a pneumatic hydraulic head moves towards the wood. A pneumatic clamp slaps down on the wood. At a certain point an electric motor turns on and a chisel digs a hole the way a dog would. This all takes five seconds.

https://www.youtube.com/watch?v=4F94V_4UNyM

I like hollow chisel mortisers better, because set up and maintence is cheaper.

[JKimel]

Agreed. The cantilevered shelf discussion just got me thinking how these machines worked.