Backyard forging Part 2: Material Reduction and Profiling

Following on from the initial hammer work that was discussed in the previous blog we are now at a stage where we have a soft tempered knife blank. This softening is known as annealing which requires metal to be heated to a specific temperature and allowed to air cool.

This was the final step of the previous blog and is important as it allows for much easier processing of the knife through this next stage.

Depending on your ability and confidence you will have arrived at a stage where your old file resembles the rough profile of a knife. You are able to refine your knife profiles the more you practice, very similar to carving with axes. The more you carve the further you are able to take each project with the axe therefore saving you a lot of time. This is also true of forging simple tools. The more you are able to shape with the hammer initially the more time this will save you having to file off large amounts of material to achieve the desired result.

 

To start the profile reduction you will need a metal working file, wire brush and bench clamp or work mate.

Those with a greater array of power tools than me can use electric files and grinding wheels. If you happen not to own them then it is not a problem and personally I enjoy the process of manufacturing the most essential of tools with my own hands. Also by using hand tools you will know that should you need to, you will be able to reproduce the process out in the field.

 

To begin with I focus on the overall profile of the knife ignoring, for now, the bevel. I make sure that I am happy with the outline and thickness of the blade then likewise working on the tang. The areas I focus my attention on are the point and belly of the blade, carrying out craft work I require a relatively fine point so that I can do more intricate work. Profiling a drop point means that the tip of the knife runs truer to the centre of the blade, rather than along the spine.

 

Side profile being shaped with the file. Notice how blade and tang are being profiled

A second area of focus is around the base of what will be the cutting edge. It is best to profile this to a sharp 90% angle meaning it will sit flush once handled.

Thirdly the tang doesn’t want or need to be ridiculously thick. I tend to keep mine around 2.5-3 mm allowing for adequate strength while keeping the weight down as well as making handling easier. I aim for the same thickness to the blade.

Periodically throughout your filing it will be of benefit to give your working files a quick going over with your wire brush. This will just clean out any build-up of filings which will start to clog up the files teeth and reduce the efficiency of your file over time.

Wire brush being used to clean out file

Once you are happy with the outline profile of your knife it is now time to start work on the all-important bevel profile.

The sheer amount of information on internet on the optimum angle for the Scandinavian grind on a knife is enough to give even the most ardent knife enthusiast a nose bleed. In the process of reading  all this I gained a substantial head ache!

From what I can decipher, the angles that are desirable lie between 18-24⁰ for the whole bevel. That is, for a 18% bevel you would have an angle of 9⁰ on each side of the knife. The deeper you dig the more you seem to drown in information, all of which I’m sure has its merits and I’m not taking anything away from the depth of information available. Only that for the purpose of what we are doing, and remember I said at the beginning of the last blog we are after a functioning cutting tool,  it goes way and above what we need.

The other consideration is that I have no means of accurately measuring the angle of my knife bevel so like the rest of the process I have worked by eye. This was done by comparison to my Mora craft knife which holds a superb edge.

 

Bevel being profiled, repeatedly check compared to existing knifes. Aiming for around 20⁰ total angle on the bevel

The best advice I can give on the profiling of the bevel is taking your time and keeping it as even as possible and as close a replica to one of your existing knives. This may seem a rather crude way of going about this, especially as it will affect the cutting ability of the knife, but it has worked for me so far.
It helps to pay close attention to how far the bevel comes up the side of the knife. I had a tendency to profile these too low and therefore at too steep an angle previously and it made the knives difficult to use. The evenness of the grid is possibly the second most important consideration and just like when sharpening a knife, it pays to keep everything even and work both sides simultaneously.
Periodically sight down the blade as you will instantly see how the bevel is straying from the centre line.

When profiling the tip of the knife, care needs to be taken not to be over zealous with the file and loose the tip. All we are after at this stage is the basic profile of the cutting edge, not a shave-sharp tool. One tip that I now use is to occasionally file 90⁰ to the cutting edge along the belly and tip. This remove some of the large burr that will have built up but also increase the robustness of the tip while it is still being knocked and banged about.

Fully profiled knife ready to be tempered

So once you are happy with the entire profile of your knife, both the shape and the bevel, we now need to consider tempering the blade to a usable state. This is what will be covered during the next blog. Giving you a week of evenings to file away to your heart’s content.

Danny Hodgson

 

 

Referencing list:

http://www.technologystudent.com/equip1/heat3.htm