Making Kitchen Knives – Part 5 – Grinding, Polishing, Buffing


I was expecting this to be the most time-consuming part and so far I was not surprised – it was. You have seen my collection of abrasive belts during my Rondel Dagger series. Because the protective coating has proved itself to be way too persistent, I had to start with the coarsest Zircon belt all over again – that is what I meant when saying that I could have spared myself the trouble I have spent with finer belts before hardening. I wanted to give this blade the best surface finish that I can achieve purely by using machinery, so I went thoroughly through all belts, not switching to a higher one unless all scratches from the previous one were removed. Although towards the end of the line with last two Trizact belts I was not too fussy about this, because those leave so fine scratches that whilst they are barely visible, but they will always be somewhat visible unless I go with hand polishing afterwards – and that I did not want to.

So when finished with the finest Trizact belt I went straight to the finest buffing compound and gave the blade a few passes on the buffing wheel.

An important note – this is a knife without secondary bevel, with so-called “convex grind”. That means that during the polishing process the blade is also sharpened to very nearly final stage. Therefore towards the end it becomes a bit dangerous to handle it, because it can actually become completely sharp in places. I do not know what process other knifemakers use for achieving this grind, I am doing it with the slackbelt/hardbelt setup on my belt grander, that way I can do it in one go during polishing. The knife will need some sharpening when finished, but not too much. I like this grind because in my experience it cuts best and also looks best – but your mileage might vary and there is no accounting for personal taste.

speaking of taste – one of my friends when I have shown him my mother’s knife thought that I have made the tip round either due to laziness or because I botched it and making a round tip is easier. If you have such thoughts, forget them. Making a round tip is not easier than making it pointy-stabby. And the round tip is entirely intentional. This time around I actually consulted with my mother what she prefers for this knife design and I discussed with her the work in progress when it still had a point, and we agreed that to us this knife looks better with a round tip. Further, there is no point in having a point on an all-purpose kitchen knife like this, since needing a sharp point is actually a rare occurrence (the only one that I remember from the top of my head is gutting fish and poultry, and even there an actual point is used only briefly).

©Charly, all rights reserved. Click for full size.

Enough rambling  Here you can see the blade before buffing to get a measure of how well the knife is polished after only Trizact belt grinding – after buffing it reflects a lot more.

That picture shows also that the grind is acceptably flat. The fact that the edges of the mirror on the wall are straight-ish and that my face is still recognizable despite being reflected back through a mirror 1,5 meter away is a good sign that the grind is flat.

However that comes at a non-trivial price. The whole grinding and polishing process took me 4:20 or 260 minutes. Buffing was mere 10 minutes from that. As I become more experienced this time will probably go down significantly, but some of that part of learning curve I have already done, so I do not think it will be too drastic. In order to shave-off a really significant amount of time here, I think I would have to either use completely different process (I have an idea there, but it will need a lot of MacGyvering), or be content with a less-than-mirror finish. So in next step I will experiment with different finishes and decide which is the best compromise between time spent versus looks. The problem with polishing is, that whilst it has zero negative impact on the function, it has 100% positive impact on the looks of the thing and negative on the price. And people are buying with their eyes but deciding with their wallets. Talk about contradictory requirements…

Comments

  1. avalus says

    A shiny piece of mirror!
    It took me a while to figure out that a knife without a point ain’t pointless.

  2. jazzlet says

    I inherited a knife that had had the point napped off at some point, lovely carbon steel, easy to sharpen to a vicious edge. I still use it, although I reserve it for boning out chickens and other jobs where a degree of flexibility is helpful.

Leave a Reply