Fundamentals of manufacturing operations

Cutting metal

Lubricate the metal saw using some oil (vegetable or mineral - doesn't matter) on the saw or on the place being cut. Otherwise the saw will get damaged.

After cutting, remove burrs using a file (or massive sharp screwdriver if you do not have suitable file).

When cutting tin with tin cutters, take care not to cut off your finger.


Before drilling, place a drop of some oil (vegetable or mineral - doesn't matter) on the place of future hole or on the tip of the drill bit. This prevents overheating the bit which makes the bit permanently blunt.

If the hole diameter is bigger than 5mm, use some smaller bit to predrill the hole and then drill it with the intended diameter. Use of a drill stand is recommended for all drilling.

After drilling, remove burrs from edges of the holes using a file or massive sharp screwdriver. You can also use a big drill bit to remove burrs by twisting it in hand over the hole.

If you drill a tin, if possible, put a block of wood under it. After drilling in tin, it is possible to remove burrs by banging them down flat with a hammer on an anvil or vice and repeating drilling if some of them got inside the hole.


If the solder iron's tip becomes dirty, heat it up and wipe it into a piece of rag or wet sponge so that it becomes clean again. If you omit this you will not be able to make a reliable joint.

Do not spare colophony and do not waste the tin. Put there only as much tin as necessary for the joint to be firm, but do not make balls from tin. Before soldering parts together, cover them with tin using tin and colophony. Then put them together and add some tin, colophony, and leave the solder on until all the tin becomes liquid, then remove the solder and don't move the joint until it thoroughyl solidifies. The surface of the tin must be clean and shiny.

Do not overheat the semiconductors. If you can't get tin on the pin and would need too long time, relax and wait until the part cools and then continue. Or hold the pin with pliers between the end and the part, so that the pliers will suck off the heat spreading over the pin.

Use a soldering iron with grounded tip. If you use those gun-style irons with a loop of thick wire, connect an aligator-clip to the loop and ground it. If not possible, at least switch the gun on and off when not touching the BF988/BF907 and 74HC??.

Placement of electronic parts

Cut the pins as short as conveniently possible. Route the wires also in possibly short routes. Do not leave neighbouring parts like resistors and capacitors in touch, because sometimes the lacquer gets corrupted and a contact may occur.


The painted surface must be absolutely clean and fat-free. Before painting, mix contents of the can thoroughly. Dip the brush and press out the paint from it against side of the can with paint. Make uniform, thin layer. After painting, immediately rinse the brush with water. Do not make second layer before time interval indicated on the can. Also honour the minimum required ambient temperature.

There is a problem that you cannot paint whole piece because you would need to levitate it then to dry. So paint only one side, stand it on the other side, and wait until it stops being sticky (you don't need to wait all the time prescribed on the can). Then paint the other end and stand it ont the dry end again. The good feature of water-soluble paint is that it dries very quickly.

Sillicone sealant

Shape the sealant with your fingers, then wipe your fingers into a dry rag completely. Do not try to wash your fingers as it doesn't work.