Saturday, September 17, 2011

Construction Photos for Serial Cable kit - Mk3/4

The serial cable kit was formally released at work last week - the usage instruction manual was completed, and the construction manual as well. Confirmed cost came in at $48.87 per kit if 20 were made, $97 to make a single using company approved vendors and their MOQs for certain parts - If Ebay was used, the price per single kit still sits around $40. Either way you look at it, it is a dramatic reduction in price compared to the Mk2 kits I made back in 2008 - they came in at $400 per kit for the same functionality as the Mk3/4 Kits.

In the meanwhile here are a few photos taken during construction, and a couple of snapshots of the finished kit, and construction manual.
Photo 1 - breadboard cut to form baseboard
The baseboard is a small segment of breadboard anchored to a baseboard which incorporates the breadboard, the serial cable terminations, cable anchors, and module "ejection mechanism"

Photo 2 - Baseboard and anchor plates - under construction
Everything in this kit was designed to minimise costs, and as such salvaged materials were used wherever possible - including salvaged screen-door extrusion for the anchor plates -the construction manual has drawings of all parts to be constructed, and alternate dimensions/ drawings if the extrusion was substituted with pieces made from simple sheet metal.

The "modules" are simply modified IC sockets, which are later labelled and "potted" for protection and resilience.
Photo 3 - "Modules" under construction
The serial cable is modified to suit the cable kits requirements. All construction for the prototype kits was made using tooling and equipment in my field desk - including the third-hand, modified pliers, solder pens, etc
Photo 4 - Serial cables being modified to suit kit
Compact/ resilient storage of the kit and components was one of the deliverables I placed in the kit design. I accomplished this by modifying a commercially available storage box, and then constructing stack-able compartments which slid inside the outer case.

Photo 5 - Completed modules in stacked storage compartment
The user manual was deliberately formatted so when printed it could be trimmed to fit in a designated space in the the container - the finished manual measures 245 x 185mm (9 5/8 x 7 1/4") and is around 25 pages thick (printed in duplex, but with 6 pages of blank paper for notepaper)

I will have to "de-crest" the manual/s if they were published here since they reference work, and the department I work in - since they were the target audience of the design.

I've blanked out the company/ section details, and my address information on the thumb-drive label - hence the white blotches

Photo 6 - Completed kit with instruction manual in lid
The construction manual contains a number of progress photos, drawings, tips and  alternate materials discussions. I wrote the manual with second year electrical apprentices in mind - some familiarity with basic hand-skills, interpretation of drawings, and the sense to know what holes get changed if you change a countersunk screw from 3/16"-24 to 4mm. The manual printed out to 29 pages of duplex A4.

Photo 7 - Sample page from construction manual
As mentioned, I'll have to de-crest the manuals before publishing them here - not a huge amount of work, but still anything which adds to my "TTD (Things to Do) list" is not overly welcome right now. If I get some time spare, I'll do it in the next week or so, and add them here: (links will reference google docs)
User Manual
Construction Manual

I'll post again when something is completed, progressing, or worth discussing.

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.