Building the Canadian Semi-Auto STEN

[Claven2]

Fine by me Monsieur Savoie

Klunk, the reamer is made from drill rod stock, you lathe it to SAAMI specification, in effect a dummy round with a pilot guide on the end, than you mill the flats in a mill to make the cutting surfaces.

To harden, it depends on the steel used. You can either casenit it, or use heat and quench cycles on the heat treat chart for that steel.

They don't last like commercial ones, but work OK for a few barrels, and they pretty much require a lathe to keep them cutting straight.

Ok, wrote the above part early this morning when I was in a rush, here's more detail...

The reamer is made out of drill rod. I forget if it is O-1 or W-1. High carbon steel, hardened then drawn slightly. D reamers are a standard type of reamer, not just chambering reamers. Basically, you turn the steel to the diameter or contour desired, and then cut away almost half. A relief is cut on the rounded side up to the edge to create the cutting edge. The edge is finished by stoning. Biggest problem is the risk of warping when the reamer is hardened. O-1 is less subject to warping than W-1. Plunged straight down into the oil or water, not on an angle or horizontal. Doesn't cut as fast as a multi-flute reamer, but if the edge is in good condition, cuts smooth, as can be seen in the photo. Making these reamers is described in older texts. A reamer to size and finish a drilled hole can be made by taking a rod the correct diameter, and cutting it with a long oblique cut. After hardening, the cut face is stoned smooth.

As I said though, it's not a project for a beginner as there is a high probability of making a mistake and ruining your barrel blank.