Intro: Making a Zero Cost Marking/carving Knife
I saw a few knives on the apocalypse challenge, but they all seem to require either buying a knife blank (not too realistic in a SHTF situation), or doing some forge work, which is a bit involved. I decided to make a small marking/carving knife out of scrap in my shop, stuff similar to what could fairly easily be scavenged. As a bonus, it has qualities that are hard to find in an affordable knife: long handle, short blade, with a straight blade going to a point. This is because I have heard for chip carving, it is easier if the blade is straight so it's more easily controllable. I also decided to give the knife a chisel bevel so it works accurately as a marking knife.
Again, my goal was not to make a piece of art, but a workable shop knife out of minimal materials and work.
I started with a piece of scrap plywood.
Step 1: Kerf for the Blade
I cut a kerf for the blade. I used a broken off piece of a reciprocating saw blade. It was thicker than my next option, a snapped hacksaw blade, and simpler than my last resort, cutting a knife blank from a dead circular saw blade with an angle grinder.
In retrospect, I regret not taking the time to properly line the knife blade up, although i probably would have knocked it out of alignment in the following steps regardless.
Step 2: Drill Holes and Cut Pins
I clamped the blade in place and drilled holes through the knife body and blade. I used a piece of spare bar stock (1/8" I believe, might have been 3/16") that has been sitting in my shop forever (you can tell by the rust lol). Brass or copper would have been better, but didn't have any on hand and wanted minimalist. Used the angle grinder to cut off the pins but you could use a hacksaw. I left the pins slightly proud on each side for the next step.
If you're scavenging, a nail will probably be easier to find or pry out. Or copper electrical wire?
Step 3: Peen the Pins
I used a cross peen hammer, I couldn't find my ball peen one. I'm not sure how I would have done it without a peen hammer, a regular carpenter hammer wont work well. The anvil was a spare piece of steel from a cheap magnet bar I pulled the magnets out of.
This is why I would have preferred a softer metal for the pins. It was a pain.
...maybe if I used the rod as a rounded surface between the pin and the hammer?
Step 4: Fill the Rest of the Kerf
Mixed up some filler with fine sawdust and hobby glue. Make sure to poke it in there to fill the whole gap, not just the edge. After filling, I clamped it down again.
Step 5: Grind the Edge Bevel and Sharpen
I used a Worksharp 2000 for it, the slow speed and air cooling means that I can worry less about the knife instantly overheating. I still kept a container of water next to the grinding wheel (you can see my whetstone sitting in it) and quenched the blade to cool it whenever it started to overheat. Protip: if you put a few droplets of water on the blade, you can see them boil off when it starts to get too hot.
I started by taking the saw teeth down to flush and getting the knife blade flush with the body, then did the bevel/sharpen. I added a tiny bit of back bevel since dead flat wasn't necessary.
This could also be done on a bench grinder if you're careful about the heat, or on a flat river stone/piece of smooth concrete (chunk of shopping center floor etc.) if you're willing to devote a few hours.
I only took the knife down to 180 grit, so not properly sharp, but I didn't have my scarysharp sharpening/honing setup up yet. I'll get it when I need to resharpen all my chisels (got a few cheap sets and just go through them and put aside when dull until I need to sharpen them all again)
Step 6: Cut the Blank to Size and Shape It
I had used an oversize piece of plywood since that was what I had on hand, and I waited to cut it down until later because drilling small workpieces can be dangerous, ditto losing fingerprints to my grinder. Sorry about the blade being offscreen in this picture.
Used a rasp to round over all the corners and put a thumb spot on the knife. I did a final smooth on the grinder to get the pins flat and flush, but it wasn't hogging away material fast enough to really shape the knife. Fits pretty well in my hand regardless.
Step 7: Enjoy the Knife
Haven't used it for carving yet, although I did one or two test shavings it really needs to be a bit sharper for that. However it worked very well as a marking knife for setting the width on a table saw insert replacement.
Already dead saw blade
Trash piece of plywood
Negligible amount of glue/sawdust
Abt 4" of steel rod stock
<1 hr of time
...Ok and a drill bit I snapped in half because boring is boring and I pushed too hard. Probably also already a bit dull since it was a fairly go to size.