Homemade drawknife from circular saw blade

You have done a great job of making this tool, keep up the good work, but I would like to offer some constructive criticism on the overall job.
1. Tungsten/Carbide saw blades are normally made of low grade steel. There is no need for them to be high carbon steel because it is the carbide tips that are doing the cutting. You would have been better to make it from an old circular saw blade, originally made without tips, or an old hand saw.
2. When making a round knife from an old non tipped saw blade it is generally considered that the outer rim should form the cutting edge. This edge has had the heat treatment and will be harder than the inner area near the spindle hole.
3. I can see from the video that the steel was relatively easy to file, because it's soft. It needs to be hardened and tempered to get a good cutting edge. Your file touched lightly on the cutting edge should "skate off" when it is hard enough. If you can't achieve this hardness your saw blade was too soft for knife making of any kind. After hardening it needs to be cleaned up, then drawn and tempered. Very light straw colour on the cutting edge and the back of the blade should remain relatively soft.

Homemade drawknife from circular saw blade - video