ПРОЕКТ КАЛАШНИКОВ
Ствольная Коробка — Резки

Receiver Fabrication — Milling

Ствольная коробка, stvol'naya korobka, the "barrel box" as the Russians call it. We have started building one.

This is one in a series of pages about the history and reconstruction of the Автомат Калашникова 47, Avtomat Kalashnikova 47 or Kalashnikov Automatic Rifle 1947 Model, designed by Mikhail Timofeevich Kalashinikov in 1944-1946. It was originally manufactured at the Ижевский Машиностроительный Завод, ИЖМАШ or Izhevskiy Mashinostroitel'ny Zavod in the western Urals.

At left you can see why this part of the project is required, and where we are so far. This original receiver has been cut into three main pieces with a saw and a torch, and most of the central part is missing.

Above that is a new receiver being built from a flat. As shown on the preceding page, the receiver flat has been built into shape.

The next step is to mill the top rails to the proper dimensions.

An adjustable parallel will keep the receiver from collapsing while clamped in a vise and cut with an end mill. Red marking dye is on the top rails, and they have been scribed with the end points of the needed cuts.

The flats are intentionally made too wide, so that even if your bends are somewhat rounded or misplaced, there will be enough material left to provide the needed rail width. Not that the receiver will work if the bends are too misplaced or ill formed, but at least you won't be lacking the needed top rail material.

The receiver is in the vise in this mill. Right now it is resting on a pair of parallels. Because it is tapered, that means that the top rails are not level. We will rotate it so the top rails are roughly level, and clamp it firmly in the vise.

The adjustable parallel is slightly below the top of the vise jaw faces.

Scrap pieces of index cards are between the work piece and the vise jaw faces. These prevent marring and better grip the work piece.

A carbide end mill bit is cutting the rail. Start by making one pass that just barely touches the rail, to produce a straight surface aligned with the table's direction of motion. We then used a commercial receiver as a reference, comparing the reference and this piece to calculate how much needed to be removed.

Do the cutting in multiple passes taking away about 0.025", intentionally aiming for about 0.005" oversized. Then one more cut should put you within 0.001-0.002".

Remember that you can always cut more away, but you can't put it back.

We added a small clamp for some of the cuts, to reduce the chatter when cutting near the ends of the rails.

Cut just a little at a time. After cutting away another 0.025" or so, deburr the cut and measure carefully.

This is the notch at the rear of the top rails.

This is now a properly dimensioned receiver.

Here we are looking straight down at the receiver. The rail dimensions we used, in inches, are:

The end mill is round, so there is a radius rather than a square step. The quoted distance from end is to the deeper edge of the radius. That is, to the narrower segment of rail.

Next step: Riveting and heat treatment

© Page author Feb 2012.