Thing of the week - Bacon and Fire part two: First Knife

Hi everybody what is going on?
I'm Roger In Technology and welcome to Thing of the Week Part Two for 30th August 2015.  This week I'd like to talk about the first knife I made from scratch.

Ferrous materials are characterised by the way iron crystallizes as it cools, and you have to master iron from the earth, air from the bellows, the blazing fire and water to quench - truly the dawn of blacksmithing represents mankind's dominance of the four elements of the ancient world.

The first step for me is to grab some one inch rolled steel stock and draw a knife on it. This is where the magic starts.

This is the steel stock I've chosen, it's about an inch wide but very thick.

This girth will give it tremendous weight and I'll have to consider that when I profile and grind it.  I'm planning a Scandinavian style grind, with about two thirds of the blade tapering to a point. Because of the thickness of the blade I might choose a convex grind instead, I'll see how it goes.

You can never have too many clamps so I clamped a clamp to a clamp.  This was an everyman project with tools you might have in your toolbox already.  Just a regular hacksaw, a file, and some clamps holding everything to a picnic table out back. I'd love to have a heavy workbench and a bolted bench vice or a leg vice, but until I get that set up it's picnic clamps all the way.

The initial cuts are all made using a regular hack saw, with a bastard file used to round it off. Its a lot easier to saw through than to file, although I found the weight of the stock was really working against me.  Lesson learned, use thin stock and you will save a lot of elbow grease.

Next step, grind the bevel. This was all done with a bastard file, clamps and some curse words that really seemed to help get the job done. The bevel isn't as deep as I'd wanted but the angle is about what I was after so that just the shape it's going to be.

Once ground, I cleaned the millscale off and polished it up with some 240 and 600 grit sandpaper. I think I might have gone finer than that just to see how much shine I could put on it, and I wanted it pretty smooth before the heat treat.

After the steel is knife shaped, Its time to heat treat the blade. First off, I'm going to pack my crucible with sugar and cap it off with clay and place the knife in it to case harden it.  Case hardening means you have to get the steel really hot and allow it to soak up additional carbon. I'm doing this because it's a low grade piece of steel stock I had that isn't really suitable for knives.
I'm going to cook the knife in sugar at about nine hundred degrees so case harden the blade a little before the quench. Since it's a soft steel, the case hardening will help it retain a really good edge. I was offered some Kasenite to harden in instead of sugar. Kasenite is a great source of carbon but it also contains Potassium Cyanide and I figured I'd stick with the non-toxic version this time.

After case hardening, the blade is back in the forge again for the heat treat. Here I'm using a graphite crucible to raise the knife to hot temperature and get it evenly cooked. I'm also cooking bacon, although the fire is a thousand degrees too hot for bacon which starts to vaporise at this sort of temperature.

OK, I said this knife was made from tools you might have lying around, and not everybody has a raging inferno to hand. But it was a very simple build and you can put one together in an afternoon with reasonable cheap materials. It's an insanely powerful fire despite its small size and can be difficult to control but if you are used to working with forge or foundry fires it isn't that bad.  For the astrophysics crowd, I've peaked at internal temperatures as hot as a Red Dwarf star and the steel bucket on the outside didn't melt. It's all about the heatproof lining.

Whole essays could be written on quenching steel, so I'll skip the details here and perhaps we'll go into those another time. The quench hardens the steel, and then the temper brings it to the exact hardness that you want. Because this is a mild steel I went with a water quench.

After the heat treat the blade is covered in scale and needs a really god grind, polish and buff so its back to the sandpaper and elbow grease for this one.

I'm hoping to get it cleaned up, tempered and get a handle on it soon. It might not be next week, just depending on how busy everything gets. But hopefully I'll have an update before long with a picture of the finished article.
This is pretty much "finished" though.  Its a knife shaped object, and its been hardened. Really it just needs handle scales pinning on.

Lessons Learned

You learn as much from your failures as you do from your successes, and while this wasn't a failure, it wasn't a complete success either and there is a lot I can do to refine the process.

Choosing such thick stock doubled the amount of work I had to do cutting and grinding and really cost me time. Its good practice on being patient but next time I'm going to choose something much thinner. It just depends on what you are trying to make.

Doing this by hand was a lot of work. Bottom line, its recreational hard graft - but still less effort and better tools that our species had for thousands of years. And I could pick them up cheaply from the local hardware store.

Next time, I'm going to want a proper height workbench and I've got to consider a belt sander too. Getting a workbench at the proper height for you is crucial else your back will ache the following day. I choose the hard way because I wasn't spending any money like this, but if I could pay sixty bucks to take away the pain right now I would consider it.  Money comes and goes but you've only got one back.

My handle pins look a little puny. I could easily have chosen 3/8 or 1/2 inch pins, and I might find something bigger when I come to do the handle. Overall I'm not that fussed - again it's about learning the process but one of the processes to learn is having an eye for what looks good, and what I like the look of.

Choosing to case harden made things more difficult. Its a way of hardening steel, which means you can start with a softer, lower grade stock. Our ancestors used to have to do it and it's not a great hardship. But I don't think I'm likely to try that again for a while. The local metal supplier didn't have any O1 steel which is what I'm after, but I found a few places I can buy one inch bar online so I'll order a few meters when I'm ready and make a few knives.

Fire! Running the fire is great fun. It gets hotter than I thought, and just for a short while I lost my nerve. Literally, it got so hot I started to get scared. So I'm going to fabricate a blast regulator to reduce the airflow.

It amazes me at every step how much mastery of the elements we have and how much power, knowledge and versatility we have within our grasp. I'm going to improve my workflow, maybe buy some more tools and have another go soon.  It's quite possible that the next few projects will be brass and bronze so it could be a while before I'm working with steel again but I want to have a few attempts until I've got something I'm happy with.

Until next time, keep your projects projecting and maintain momentum - and Clamp everything down!