… there was a bar of steel.
After a short break due to harvest I have started two knife making projects and I will share the progress on them as I go along.
The first one is about developing a viable process for making small-batches of kitchen knives.
The knife that I have given my mother for Christmas has proven itself to be an excellent cutter. It held an edge for half a year and still shaved hair when my mother requested honing the edge because it had a few blunt-ish spots. The handle does not show any sign of deterioration too. And it is used daily, by at least two people, on everything from fine chopping veggies to de-boning chicken. So I think that with some adjustments (mostly making it look prettier) it might be a saleable product.
I reckon (I will not bother you with the math and reasoning, some of it has solid rational basis, some of it I pulled out of my nether regions) that in order to be able to eventually barely survive whilst making knives, I would have to be able to make a passable kitchen knife in under five hours spending with the fun work, i.e. manual labor. The lower the better. Rest of the working day would in such a case be eaten by the unfunny part of the job, the actual business of business.
But developing a viable production process is something I have a professional experience with and so I want to have a go at it, even though right now making knives is just a hobby. And I will be sharing with you all the failures as well as the improvements in trying to achieve my time goal.
The first step is straightening the steel. For this project I am using N690 steel 1,8x50x500 mm and all the steel bars had a slight bend to them that had to be corrected. Currently the only way for me to do this is to use a vice and three thick screws. Had the plates had a kink, I would place the middle screw straight on that kink and bend it with ever-increasing pressure until after taking the steel out of the vice it would be straight-ish. However these did not have a kink, they were nearly universally bent in a very slight regular arc. To straighten that, I first tried to bend the bars slightly at multiple points. It worked, but it was time-consuming and unreliable. Later I have tried to close the vice only slightly on the steel bar and then pulling it through the screws – essentially using it as an improvised roll bender. That worked much faster and reasonably well.
Even soo, all in all it took me less than 1 hour to straighten 12 knives worth of steel. That is less than 5 minutes per knife. I think that building a small roll bender specifically for straightening these thin long bars should not be difficult and it could potentially shave off quite a reasonable chunk off of that too. But right now, I am putting this into the “high hanging fruit” basket, since despite the clearly impromptu setting it takes only about 2% of my time goal. That means, I will ignore this step in the process for now and not bother about improving it.
For the first knife made let’s write down 5 minutes for this step and move on to the next.
I’m going to enjoy this, thank you for sharing with us Charly!
This is good.
Walter Sorrels (and every other experienced blade-maker I have ever heard anything from) always points out there’s a specific order to doing things:
1) make sure it’s straight
2) then do your shaping grind
3) then harden/temper it
4) then do your finish grind
5) then polish starting with coarse grit and do not ever go ‘up’ a grit until you have all the scratches out from the previous
I’ve had the experience of missing a scratch that was made with 80 grit and then thinking “I’ll just polish that out with this 600 grit” -- it doesn’t happen. There isn’t enough 600 grit sandpaper to get that scratch out. Or there’s not enough time.
And if your metal is not straight, don’t finish grind it because then you’ll think “I’ll just bend that a wee bit” and it throws your whole shaping grind off and you’re basically back to square 1.
This is going to be interesting! As usual I will have no worthy contributions to share, but I will surely be reading along.
Oh, this will be a fun series! I have to figure this out in my work too, how to make an item into a production process so I can get it done faster. Sometimes I really have to think outside the box to work it out, and there is always room for improvement, at least for my work.
I’m also going to enjoy this series. I’ve become fascinated by knife making thanks to you and Marcus. My dad would be proud. He started out as a blacksmith in Germany and ended up as a welder in Canada. He talked a lot about metal tolerances and I’m afraid I tuned most of it out, but he never did much work at home either. Well except for making our porch railings. That was cool.
5 minutes is a great beginning for your project, Charly. I had another look at the knife you made for your mother. It looks very functional for different kinds of cutting and it’s beautiful. I wish you continued success.
Charly,
You just need 3 bearings that are complete with inner and outer races that are a single unit, and for this run of knives, the races 50 MM wide. Mount 2 solid on 150MM centers.
The 3rd mount on an adjustable Fine thread slide above the two stationary bearings.
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As you adjust the top bearing down into the stationary bearings, and run the steel back and forth, it will roll out the bend gently, until you have straight steel bar, with no kinks by static bending. Very fast, and overbending corrected by flipping the bar and straightening the other way. Actually, that de-stresses the steel, so it is more neutral in it’s internal stresses.
R
Looking forward to your work in progress.