In the manufacture of models or devices containing frequently unscrews detail, there is often a need to do the knurling (knurled) outer surfaces of the nuts or screw heads. With this purpose usually use a special device consisting of one or two fine teeth hardened rollers in the mandrel. During rotation of the part fixed in the Chuck of the lathe, the teeth of the rollers are pressed into the surface and form therein a corrugation. With the appropriate equipment the operation is not complicated. However, if you want to make knurled at home?
In this case I can recommend a simple and proven practice method. You need only a regular bench vise, two identical new flat file, a hammer and two of the round rod or nail, preferably with a minimum diameter of 5-6 mm.
The method is as follows. Detail on the surface where you want to ribs, is placed between the two files in a vise. At the same time between one of the files and sponge grip set nails the role of the rollers. The distance between nails is chosen small to reduce the bending-moment acting on the mobile file but not the least is 1.1—1.5 diameter of the workpiece, the surface of which is knurled. The whole system is compressed in a Vice. You need to be very careful not to break the mobile file, working on the curve. Working surfaces of files when you install oiled.
The scheme of rolling with the help of files:
1 — mobile file; 2 the grip; 3 — rollers (nails); 4 — fixed file; 5 — detail
Clamped a vise, hit with a hammer on the movable file — so that part has made one revolution. Then, after additional preload screw vise, the operation is repeated in the opposite direction. Usually the slab is quite satisfactory sometimes only two or three longitudinal strokes of a file (of course, in good condition last). The best results are obtained by the use of files with a small notch — in increments of 0.5 mm.
To avoid injury, you must work with glasses, and the end of a file, which has a hammer to protect an overlay of soft metal.
V. ZVEZDAKOV, Barnaul