Saturday, September 3, 2011

solder pens, electronic tooling, and catch up

I was at a course the other day and one of the whiteboard markers ("dry-erase" markers according to Dilbert) ran out - I intercepted it before it got tossed out to make another "solder pen" No-one at the course had heard of them, so here is a quick explanation and construction article.

When I first started in electronics I simply used solder held in my hands - quite mindful of the warnings regarding lead poisoning, and always washed my hands after working. I don't remember where or when, but somewhere I saw someone use an old de-soldering wick packet to hold small coil of solder (see picture) - this became my preferred soldering method for the next 10-15 years.

When I built the field desk, I set about duplicating my old faithful toolkit, and found I didn't have any spare de-soldering wick packets...hence I turned to the soldering pen idea. I can't claim credit for it's invention, it's been around for years in various guises from clear containers with the solder poking out, to references on aus.electronics to people filling chemy pen (permanent markers) cases with solder.
Photo 1 - Original "solder - holder" and de-soldering wick
So how to make a solder pen - select an old marker which has run out of ink, and remove the nib (pliers simply pull it out) and then get the cap at the end out. Sometimes it's necessary to trim away about 10mm (3/8") of the outer case at the end to allow the end-cap to be removed.

Photo 2 - dismantled marker pen

Then measure the internal length of the casing, and select a screwdriver or other thin smooth rod as a mandrel.
Wind the solder around the mandrel to match the length of the length of the case internals leaving around 50mm (2") of solder free at the start - this starting piece will end up being the first of the solder to be used. once one layer has been wound to the correct length, carefully wind back over for a second layer, stopping about 2-3 turns shy of the beginning of the first layer. Keep winding back and forth adding layers neatly until the wound solder is a loose fit in the case.

Photo 3 - screwdrivers being tested for length

Cut or break the solder at that point, and gently remove the screwdriver (I found gently rotating it made extraction easier). The bundle of solder will be quite flexible so care must be taken to not stretch or kink it.

Photo 4 - solder bundle completed

Straighten the starting piece of solder, and centre it along the axis of the bundle, then feed it into the marker case so the starting piece protrudes where the nib used to be... this means the coils of solder will feed from the inside of the bundle, hopefully preventing tangles.
Replace the end cap, and you can fold the protruding solder over the nib holder and replace the original cap.

photo 5 - Solder test  inserted into marker body

In use, simply remove the cap, tug an inch or so of solder out, and apply solder as required by holding the marker body. As the protruding solder is consumed, simply tug more out of the marker body as required.

I measured the weights of all my solder pens, and found they averaged 50gm (about 2 Oz) of solder in each one.
Photo 6 -  solder pens completed  with other tools
A bonus tip...
When I was at uni, I got on to a bulk purchase of quality electronics tools - cost us $120 to get excellent tooling - a fortune back then. When I duplicated my kit into the field desk, I wanted similar shape and quality tools, but did not want to spend too much money.
I purchased cheap pliers from the local KMart, and then using grinders, and files, reshaped them to suit my needs. In photo 6 you can see 2 pairs of pliers I've reshaped - the yellow handled pliers are just as good to use as the expensive ones in my old kit. The red ones are too small for use, but are handy for periodic use with the yellow pair for straightening or bending wire.

What else to talk about....
I finished the serial cable kits - Mk3 and Mk4 in total. Mounting boards, storage containers, etc. I've practically finished the user manual, and have only 2 sections left in the construction manual to finish... Mostly final edits in the sections, then renumbering the photos and illustrations. Still deciding if the documents should be published here or not, but I'll most likely add some of the construction photos at the minimum..

Various things happening at work... not much to talk about yet, but I daresay I'll have something to talk about soon.

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