A simple jig can be used to draw a fine insemination tip on the end of a capillary tube.
A tube is held vertically in the jig, clamped at the top. The top clamp is made from an acrylic block supported by two steel rods. The block is clamped to the rods at a suitable height using grub screws threaded into the block. A weight is attached to the lower end of the tube. The weight is made up of a collection of penny washers clamped together. The weight can be increased or reduced by adjusting the number of washers. The tube passes through a coil of Nichrome wire.
Connecting the wire coil to a 12v battery charger heats the coil and the capillary tube sufficiently that the tube starts to melt and is stretched by the attached weight. This only takes a few seconds.
Once cooled, a thin wire of 0.17mm diameter is carefully threaded into the tube as far as it will go. The tube is then cut in line with the end of the wire resulting in the internal diameter of the hole in the end of the tip being of the correct size. Polishing the end of the glass tip, to remove any sharp edges, without breaking it isn’t easy. Fortunately the capillary tubes are not expensive and you get two insemination tips from each tube.