SAK saws don’t have a typical outward set to prevent binding that a normal saw does, the profile is similar to a cross cut saw with a taper to the centre on alternative teeth, however they are ground more like a serration than a saw tooth
I hadn't tried it yet. But this method shown in the vid is an interesting take on sharpening these. It might work well enough, as long as the saw isn't allowed to go severely dull. The blade is laid flat to the sharpening media (both a flat diamond file and sandpaper on wood are demo'd here) and the sharpening is just a matter of grinding the flat sides of the saw blade. This method can presumably work because of the lack of outward-set teeth on the blade, as mentioned in the previous post.
Interesting question. I asked myself the same. The video from Felix Immler has already been mentioned. You could try (I have no experience with that) to use a file or rod to sharpen each tooth. Bryan Lynch demonstrates in his Victorinox Swiss Army Knife Camping & Outdoor Survival Guide how to sharpen the saw. He uses a Diamond pen sharpener / rod, something like this one (don't know what exactly he uses): https://www.amazon.com/-/de/dp/B01MT3EREP/ref=sr_1_2?__mk_de_DE=ÅMÅŽÕÑ&dchild=1&keywords=diamond+pen+sharpener&qid=1587824136&sr=8-2 But you will have to be careful not to round up the teeth. Another try could be a triangle rod, like those Spydercos for the Sharpmaker: https://www.knifecenter.com/item/SP204D/spyderco-triangle-sharpmaker-diamond-rods-set-of-2 They would have the advantage that you could sharpen the whole profile of a tooth. But those Spyderco rods are quite expensive. Maybe there are cheaper options? For example such three-square Silifix grinding sticks https://www.fine-tools.com/schleifstab.html They are not that fine. I don't know if this would work. A moment ago I tried a EZE LAP Hone & Stone but wasn't satisfied. They seem to be too thick to slide in between the teeth easily. Generally spoken you would have to sharpen every single tooth from one side in one direction. And same from the other side.
The saw in my field master is starting to get a bit dull from use. I fully intend to try Felix Immler’s technique of thinning the sides.
Several years ago I bought a used Hiker at a flea market and the center portion of the saw was dull. I took it to a professional saw sharpener.He said the teeth were set more like a Rip Saw. He put it is his jig, adjusted the settings and had it like new in ten minutes.
Rips are cut perpendicular to the plate, nothing like a SAK saw from what I remember of them, where as cross cuts are at 45
