DRILLS... RAZORHams often have to drill into circuit boards of a large number of holes of small diameter. To do this a serial drills is not very convenient — too big size. And slim drill not so easy to squeeze in a larger cartridge.

I came out in the following way: made microelectrodes… dilapidated electric shaver “Kharkiv-15” (suitable and other modifications of this brand, and “Agidel”). Homemade removable boring head set instead of knives.


The head is a single-stage gearbox with two parallel shafts on which are mounted gears with number of teeth 14 and 39 (from electric shavers of the first releases). The input shaft is connected to the motor, and the second with a cartridge of No. 1 factory production.

The casing head is machined from duralumin; it is attached to the shaver landing flange with thread M22X1 and a homemade nut and is closed by a lid with two screws М3с head screws. Side mounting cutout in the housing (it serves in the Assembly of the bearings and gear output shaft) is masked clip, clip-on case with a screw M3. The yoke has a mesh knurled, which helps to screw the drilling head in thread M22X1.


Design of microelectrodes.

Design microelectrodes:

1 — razor, 2 — case drilling heads, 3 — lock nut M22X1, 4 — pin Ø 0,8X8 mm, 5 — yoke, 6 — M3 screw, 7 — pin Ø 0,8X5 mm, 8 — small gear, 9 — shaft, 10 — cover 11 — bearing No. 1000083 (2 PCs), 12 — cartridge No. 1, 13 — secondary shaft 14 — bearing No. 24 (2), 15 — large gear, 16 — pin Ø mm 1X7, 17 — homemade snap ring bearing, 18 the separator, 19 — ball Ø 2 mm (6 pieces), 20 — foot ring.

Input shaft, machined from steel 45 (Ст40Х) rotates in two radial bearings No. 1000083, secondary (of the same material) in three bearings, two of which, No. 24, one (resistant) homemade.


Those who wish to do the same microelectrodes, suggest to simplify the design. For example, a couple of bearings of a secondary shaft (No. 24 and improvised) to be replaced by one angular contact right size; the clip and the cover to combine into one part, then no need for a seat for the cover, as well as in the side mount screw.


The duration of continuous operation of the “Kharkov-15” or “Agidel” (strong heating) of about 12 min. During this time I was able to drill 210 Ø1 mm holes in glass-textolite Board with a thickness of 1.8 mm.



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