Attach a spool of wire and a hypodermic needle to a ball point pen barrel to make an aid to make point-to-point wiring easier to do. The board shown is a microprocessor system board with a 8085, 2764 and 6464 - that is, the CPU, EPROM and RAM - and some additional glue circuitry.
Step 1: The parts
A hypodermic needle. Get the disposable type with a plastic collar, as this will need to be cut down to make it fit in the nozzle of the ball point pen.
A (used) ball point pen. I acquired one with a metal nozzle as it would probably last longer.
The spool of enamelled wire was from a relay, 12 V changeover contacts - the rest of the relay was dismantled with care not to damage the spool of wire. Other sources are transformers and rf chokes.
Some two component epoxy to cement the needle to the nozzle.
A screw long enough to hold the spool of wire (not shown)
A (used) ball point pen. I acquired one with a metal nozzle as it would probably last longer.
The spool of enamelled wire was from a relay, 12 V changeover contacts - the rest of the relay was dismantled with care not to damage the spool of wire. Other sources are transformers and rf chokes.
Some two component epoxy to cement the needle to the nozzle.
A screw long enough to hold the spool of wire (not shown)
Step 2: Putting it all together
First, some copper wire was placed inside the needle to prevent its bore from closing up, and its sharp point was ground square on some fine emery paper.
Its plastic collar was cut to make it fit inside the nozzle of the ball pen, and it was fixed in position using some two component epoxy glue.
The screw was heated and poked into the side of the pen, and on cooling it was unscrewed. The spool of wire was placed on to it, and it screwed back on. The wire was led through the body of the pen and out through the needle tip.
The thin tip of the wiring pen enables it to be used to snake the wire through tight spots, and to make connections to tightly packed integrated circuit socket pins.
To make a connection, the (enamelled) wire is wrapped once or twice round the ic or socket or component pin. Heating the joint, and applying some solder will complete the joint - if you are lucky enough to find some 'self fluxing' enamelled wire. This sort of wire is coated with the sort of enamel that changes to flux when heated to soldering temperature.
I prefer to use normal, tough enamelled wire, as the chances for accidental short circuits is reduced while using this type of wire. The joint has to be heated and then the enamel can easily be scraped off using a sharp edge of a small jewelers screwdriver. Then solder is applied and the solder will attach to the freshly exposed copper.
I used to make all my prototypes this way, until the coming of the flash microcontrollers with on chip program and data memory, which does not need this scale of wiring in order to work.
Its plastic collar was cut to make it fit inside the nozzle of the ball pen, and it was fixed in position using some two component epoxy glue.
The screw was heated and poked into the side of the pen, and on cooling it was unscrewed. The spool of wire was placed on to it, and it screwed back on. The wire was led through the body of the pen and out through the needle tip.
The thin tip of the wiring pen enables it to be used to snake the wire through tight spots, and to make connections to tightly packed integrated circuit socket pins.
To make a connection, the (enamelled) wire is wrapped once or twice round the ic or socket or component pin. Heating the joint, and applying some solder will complete the joint - if you are lucky enough to find some 'self fluxing' enamelled wire. This sort of wire is coated with the sort of enamel that changes to flux when heated to soldering temperature.
I prefer to use normal, tough enamelled wire, as the chances for accidental short circuits is reduced while using this type of wire. The joint has to be heated and then the enamel can easily be scraped off using a sharp edge of a small jewelers screwdriver. Then solder is applied and the solder will attach to the freshly exposed copper.
I used to make all my prototypes this way, until the coming of the flash microcontrollers with on chip program and data memory, which does not need this scale of wiring in order to work.
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You can also buy non-super-sharp ones in bulk from mcmaster or places that sell solder-paste dispensing syringes.
http://www.instructables.com/id/Precision-Wire-Stripper---new-video-links/
i would be very grateful...
I've attached the fabulous work of Markus Gritsch who is a world class talent on applying EWP. You can see the related page on his site.
Also take a look at Roadrunner Electronic Products Ltd. who seem to be the #1 EWP tool maker
Lastly, there's a good tutorial on EWP.
The solderable magnet wire is still available; I bought a 1/2 lb (230g) spool of Belden 8058 "Beldsol" 36 AWG (0.01 mm2) wire on eBay for $40.
The Mouser catalog says about this wire:
Dual insulated magnet wire that combines the excellent dielectric characteristics of Polyurethane and the known toughness and solvent resistance of a Nylon overcoat. Rated by IEEE tests for 270°F usage and will solder without insulation removal at 750°F.
Mouser Electronics has this wire: http://www.mouser.com/Search/Refine.aspx?Keyword=beldsol though it costs about $53 for the 34 AWG (8057) and $61 for the 36 AWG (8058) in 1/2 pound quantities.
The wire has on its label the following note:
This magnet wire may be different from what you have previously purchased. This insulation has been improved so that it will stand more heat (130°C) and it can be stripped by use of a soldering iron or gun at (750°F).
There are three other detailed images there.
Note in this image the spool of Belden Beldsol wire that I got recently.
As I recall, it was helpful to use your finger on the side of the pen where the wire was exposed to modulate the tension. When you wrapped the wire around a component lead you wanted tension; when you were just going to another point you didn't.
Anyway, for those of you wanting to make one of these dispensers, note that surface mount pcb assembly technology uses the type of needle tips pictured in the instructable for dispensing electronic solder paste and glues (except that the tips are already ground down for you).
These come in a variety of gauges from 14 to 30. They are available in single unit quantity (at http://store.sra-solder.com/section.php?xSec=9 and probably others) and are so cheap ($0.15 each) that you should be able to buy a full set of gauges for a couple of bucks.
On the other hand, the company I mentioned has a minimum order amount of $25; of course, they carry an excellent line of cheap soldering tools (no, I don't work for them, but I am an excited new customer), so it may be harder to stick to $25 maximum than $25 minimum. ;-)
Also, the type of wire he mentions is traditionally called "magnet-core" wire. Some of the best rework I've seen has been done using this stuff. To answer one of the concerns mentioned in other comments, it typically doesn't have the same problems peeling away from the wire that the Kynar wire-wrap coating does.
Cheers!