Marking Knife From Old Saw Blade

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Introduction: Marking Knife From Old Saw Blade

About: Electrical dude. Homeowner on a mission to break everything (and then hopefully repair it).

This marking knife project came out of sheer boredom last Saturday when I was looking for an excuse to avoid cleaning my garage.

This was my first attempt at anything like this and I know to any knife enthusiasts I skipped a huge step of hardening the metal. But to keep this build short and simple, I decided to skip that and the blade came out plenty sharp but we'll have to wait and see how well it keeps a sharp edge.

Also, everything I used was materials I had left over from other projects and an old circular saw blade I haven't used or seen for years.

Some safety tips and musts which I always learn through experience:

  1. Wear safety glasses/shield and a mask when cutting or sanding metal
  2. Cut warning. The metal will be sharp and jagged in the early stages.
  3. Burn warning. The metal will get hot fast, I burnt my fingers while using the belt sander for ~.5 seconds (that's why I wore gloves which I would never normally do with that tool)

Supplies

Materials used:

  • Old circular saw blade 7 1/4"
  • 1/8" strip of Wenge (mine was 1 1/2" wide)
  • 1/8" brass rod (only need a couple inches)
  • Quick set epoxy (I used JB weld 5min ClearWeld)
  • Danish Oil (Natural)
  • Oil/Wax to prevent blade rust

Tools I used:

  • Angle Grinder
  • Table saw
  • Belt sander
  • Finishing sander
  • Drill with 1/8" bit for metal
  • Assorted wet/dry sandpaper
  • Hacksaw (for the brass rod)
  • Pliers
  • Files
  • Tape
  • Clamps and a vise

Step 1: Trace and Cut Out the Rough Shape of the Knife

I used a small ruler and sharpie to trace out the shape of the knife on the saw blade. I didn't have set dimensions in mind, I just made it a bit larger than my store bought marking knife.

I clamped the saw blade to my work top and cut out the rough shape with the angle grinder. Careful the metal will be super hot after cutting. Then I used a vise and file to get any of the large burrs off.

Step 2: Sanding and Then Some More Sanding

Using the stationary belt sander and my burnt fingertips, I sanded all the edged smooth and shaped the knife as best I could.

Then using the finishing sander and by hand, I worked my way through a bunch of grits until I was happy with the level of smoothness and polish. The compare photo is between the 500 vs 2000 grit steps.

I also used this step to compare my knife with my store bought one to make sure I was on the right track.

Step 3: Getting a Handle on Things

For the handle, I rummaged through my scrap bin of fancy woods and settled on a strip of 1/8" Wenge which I thought would look great with the brass.

I used my small parts sled on the table saw to cut the wood down to be just slightly larger than the blade so I had plenty of room to sand everything flush later.

I picked 2 evenly spaced points on the handle for the brass rods and drill them out. Then I used double sided tape to attach and drill out the holes in the wood one side at a time. I made sure that the wood protruded a bit on all sides so it didn't end up short anywhere.

Step 4: Test Fit the Brass Rods and Epoxy It Up

While the handles were still held by the double sided tape, I test fit the brass rods and found them to be nice and snug. I then marked and cut the rods slightly longer than they needed to be and disassembled everything and prepped the epoxy.

Starting on one side with the brass rods already inserted I added epoxy and stacked the blade and other side of the handle making sure the rods stuck out just a bit on each side. Using claps I made sure everything was aligned properly and I let it cure for a little over an hour. Perfect time for a lunch break.

Step 5: Smoothing Out the Handle and Getting Things Sharp

After the epoxy was fully cured, I took a file to the brass and got it as flush as possible with the handle. Then I hit all the sides on the belt sander until everything was flush and smooth as can be.

At this point I was also finally ready to put an edge on the blade. Using the belt sander I freehand tried to replicate the angle of my store bought knife. It took a few tries but I finally got an edge I was happy with.

I finished up the blade with a sharpening stone until it was ready to cut things up.

Step 6: Finishing Touches and End Result

After testing the blade for sharpness and how well it marked wood, I was finally ready to apply a finish. I wiped on a coat of Danish Oil and rubbed/buffed it smooth when dry.

Overall I'm very happy with the end result. It works surprisingly well and I think it looks and feels great... Especially for my first attempt at making a knife.

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    3 Comments

    0
    leetetj
    leetetj

    10 months ago on Step 6

    great work, I think I'll try it

    0
    Stevens Workshop
    Stevens Workshop

    11 months ago

    Love it... I need a marking knife and I have an old dull blade... Have a guess what I'll be doing on the weekend.
    Thanks for posting

    0
    RPBCACUEAIIBH
    RPBCACUEAIIBH

    11 months ago

    That's tool steel for sure it should have a good edge retention. One thing that could be an improvement is making the handle in a way that your hand can't slip forward when you push it hard.

    Ps: I also like the making new tools out of broken ones. I managed to broke my side cutter the other day, and I tried to weld it, but it just wasn't strong enough, so I got another one, and I made a precision knife thing out of the broken one. :)

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