Ditchfield : one molecule thick, so I've read.

I did it. My Spartan now has a sparking wheel <img src="images/graemlins/grin.gif" alt="" />. The knife still needs some serious cleaning and the scales could use a better finish <img src="images/graemlins/blush.gif" alt="" />. I post now anyway before I have to dig up a long forgotten thread to do so.
The sparker uses ordinary lighter flints. This should make it easy to aquire replacement.



The old scales where warped beyond repair so I decided to make new ones. I used aluminium as it´s more stable than plastic. The scales are snapped on just like the plastic ones. I went for a two layer design for the scale with the sparking wheel as it was easier to build. The layers are held together with the two screws on the left. The third screw holds the sparking device.
Here´s a picture of the sparking wheel:



The main body of the sparking device has a 6 mm square cross section. The rib is 3 mm thick and slips under the upper layer of the scale. It has a hole with a M 3 thread and there is sufficient room for pockets to hold spare flints (I haven´t made those pockets yet).
The sparking wheel protrudes enough for spinning and does not impair the use of the blades. The flint and spring are inserted from the bottom and are held in place with a headless screw. The screw can be used to adjust the pressure on the flint. The spring and the sparking wheel are scavanged from an empty BIC. I forced the zinc discs off (that is easily achieved with two pliers) to reduce bulk.



The best way to use the sparker is to hold the knife in the fist and spin the wheel with the thumb. Due to the design it´s hard to spin the wheel in the wrong direction. At least with the Spartan the wheel can be used with the left hand.
I tried cotton balls and cotton balls with vaseline. Both could be ignited with the sparks.
The device could be used without the SAK but it´s hard to hold. I rate the device as adequate for fire starting. I think that it could be really hard to operate with cold hands or gloves. It requires tools to replace the flint and replacing the flint can be difficult as there are small parts that could be lost.

Conclusion :
Adding a sparking wheel to the SAK is feasible. It adds about 3 mm of bulk. The small size makes use hard in certain circumstances. The intended use of the knife is not compromised. The sparks are not great but good enough to ignite good tinder. I would consider it a novelty item. I would not rely on it as a primary means of fire starting.

For the curious:
No electro powered tool was used to build the scale and the sparking device. I used a hand powered drill, a saw and a couple of files (mainly 10" #1 and #3 and a 4" square #3 for the wheel slot)

Max,

Fantastic - that location is exactly as I envisioned it. Great! Thanks for the report. For certain on my winter project list now!

Regards,

Tom

If you just want a flint on your SAK, try this. Get one of the Victorinox corkscrew insets with the small eye glass screwdriver in it. Insert the corkscrew insert backwards into the knife's cork screw so the screwdriver blade faces out. Grab the screwdriver blade with a pair of pliers and pull it out. Take a Spark-Lite plastic striker and saw off the end opposite the spark wheel and remove the spring and round flint. Adjust the size of the hole with a drill bit and take the flint and glue it into the corkscrew insert. Ounce the glue has set, use the file to rub angaist the flint to make sparks. Be carfull as the flint is not terrible strong.

Very cool.

1. I think if you used the wheel and flint for a Sparke-lite instead of a Bic lighter, the performance would be better. The parts of a Bic are meant to be disposable.

2. Consider using a headless screw with teh same size slot as eyeglasses. Then add the eyeglass attachemnt in the corkscrew.

Thanks for your hints for improvement.
There are some design constraints I didn´t mention. Those constraints would be obvious when you try to build it.
1.) The device already goes pretty close to one of the rivets that hold the scales. A bigger wheel could make it neccessary to redo the riveting.
2.) A bigger wheel would have to protrude more in order to spin it.
3.) The use of lighter flints was an essential design feature. It should ensure that you can buy replacements virtually everywhere.
4.) The screw that holds the flint and loads the spring has to have a core diameter of at least 2.5 mm (the diameter of the flints). M3 happens to have that core diameter. If you take a M3 headless slotted screw it can be driven with the small eyeglass screw driver.

The screws that are visible are M3 counter sunk. I used a counter sunk head screw for holding the sparker because the slot is less prone for damage and could still be unscrewed if the slot is slightly damaged. A headless slotted screw could be virtually impossible to remove if the slot or thread is damaged.

In my location I have no supplier for the Spark-lite. So it wasn´t an option for me.
Apart from that I wanted to keep the costs low as this was just a feasibility study.
I found that the sparking wheel of a BIC lighter doesn´t show signs of wear after the lighter is empty. The design allows fairly easy change of the wheel. So I don´t see a real problem with this.

Maybe the members who try to modify their SAK with a sparking wheel could give a short report on their solution. I´d be interested in that. When the flaws of the actual designs are ironed out, the sparking wheel on the SAK may even become a real preparedness item.