polprog, 30 mar 21
Back to homepage
Wire-wrapping is a mostly forgotten method of electronic circuit assembly from the 70's. When I build my prototypes, I sometimes use a similar technique for connecting wires to pin headers. I wanted to try wire-wrapping but the cheapest manual tool is $20, which is pretty expensive. The actual tool is pretty simple and can be built with some basic tools at a workbench.
A wire wrapping tool is a small straw with two v-shaped cuts and a small hole on one end. The hole is used to fasten a piece of stripped wire, then the tool is used to wrap the wire tightly several times around a pin. A new tool from china is about $20 but we can make one way cheaper.
1. Cut off the pen cartridge tip with the blade (do not use a saw). This needs to be a clean cut.
2. Put the cartridge in a vice, heat up the metal pin and melt a small hole in the straw wall about 1.5-2mm from the end
3. Using the drillbit clean the inside of the straw, that is, insert the drill into the straw and spin it to a moderate speed, working the inner walls of the straw back and forth. You need to cut away the plastic that was molten and pushed inside the straw. This is important as you will have to put the wire through that hole when using the tool.
4. Use the drillbit to enlarge and correct the hole you just made. You may need to repeat step 3 if the inner edge of the hole is no longer smooth (because some plastic shreds got into it). You may want to give it an angle towards the end of the straw
5. Test the tool - strip about 3/4" of 30AWG kynar wire and insert the end into the straw so that it exits through the hole in the side.
7. Put the end of the straw with the wire on a pin header pin or an IC leg, and twist it several times one way. The unstripped part of the wire may twist around the tool, that's OK. The stripped end should wrap around the pin several times tightly.
8. Enjoy the tool you've just made. You can use the pen body as the grip to make the tool more ergonomic, use some glue to fasten the straw inside it.
Wire-wrapping is a very fast and easy method of making connections. You should try it!
Back to homepage