Round files

Support an hemispherical iron dish of 10 cm. diameter (or an iron crucible) on a ring stand and place in it about 75 g. of sodium nitrate. Heat the nitrate until it melts and just begins to evolve bubbles of oxygen. While maintaining a steady temperature, drop in pieces of granulated lead or chopped-up lead pipe, stirring well with an iron rod (old round file) after each addition. A little more than the equivalent of lead should be added, since some of it will be oxidized by the air. For this reason, a flat iron sand-bath dish is not suitable for the experiment. The reduction of the nitrate is rapid, and if much lead is added at a time, the mass may become incandescent. 

Use needle files to smooth the rough edges. Use flat files for flat areas and outside curves, and use semicircular and round files for inside curves. 

Electrode, iron, spiral, about 18 gauge wire, P. 17 File, round File, triangular... 

Four 1 inch deep hacksaw cuts are mqde in each end of the tube. This witi produce 8 evenly spaced slots, 1 Inch deep. Bevel the inside edgea of both ends of the tube with e round file or sandpaper. Place a hose clamp on each end of the tube end screw down flngertight. 

Various flat and round files, depending upon what is available to you. A machinist s scraper or a sharp knife is also helpful for removing burrs from inside the tubing. 

As in Figure 11. cut two 1/8 inch rings from the scrap tubing to fit in the middle of the holders. This allows you to automatically push each section an equal distance to the middle. With a round file or sharp knife, ream out any rough edges or burrs from the inside edges of the tubes and rings. 

The round file is of circular cross-section, parallel for approximately two-thirds of its length and then tapering towards the point Second-cut and smooth files are single-cut, while the bastard is double-cut This file is used for enlarging round holes, elongating slots and finishing internal round corners. 

The half-round file has one flat and one curved side. It is parallel for approximately two-thirds of its length, then tapers in width and thickness towards the point. The flat side is double-cut and the curved side is single-cut on second-cut and smooth files. This is an extremely useful double-purpose file for flat surfaces and for curved surfaces too large for the round file. 

Locate and step drill the two 1/2" diameter holes 1/2" deep. Cut the 1/8" wide x 1/16" deep gate using a small round file. 

Chain modification with a file guide and round file is essentially the same as with a grinder, but when modifying by hand, I file a 45° hook on each cutter instead of a 50° hook. This is because the round file leaves an edge that is hollow-ground if the hook were filed to 50°, the cutting edge would be weakened. 

Probably one of the most common complaints from people who use the U.S. CFR is How do you wade through hundreds of pages of standards and make sense out of them From time to time you may have experienced this frustration and been tanpted to throw the standards in the round file. 

Metal file. Once you cut copper pipe, you ll want to smooth the rough edges with a metal file. It s worth having two files on hand a half-round file, with a flat and a round side, for de-burring metal and a rat-tail file (it s round and tapered, as its name implies) for filing concave surfaces and enlarging holes. 

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