DIY BLADE QUESTION

[aadhaulya]

After seeing the wonderful DIY stuff on blades specially the finish of the blades by the experts here. I have also decided to attempt a 'Machete' about 2 to 3 feet long blade.
I have bought a 'Stainless Steel' plate 5 mm thick for the job (no idea of the steel specification). Now my questions are as follows.

1. Does it require heat treatment? If yes, then as per my idea I will heat it up in a charcoal barbecue and instead of quenching it, let it cool down in the ashes of the charcoal overnight. Will this be a suitable treatment for making such a long blade??
2. If it does require heat treatment, then when should it be done. Before starting, after cutting or after sharpening the edges. Most probably I would be using an angle grinder with a SS cutting wheel and later using it with a fine grinding wheel.

I would be grateful if I could get an idea soon, so that I may start on my project soon.

Regards

Atul

[goondasmani]

i am not blade expert here but i do know some basics. yes heat treatment is needed for blade. if your are using charcoal its good if you use a blower. two types of quenching is done as i know first the metal is heated up and then cooled down for gradually(this can be done several times), then its heated up again and quenched in oil(you can do this first if you want).its good to heat treat after u cut out the blanks and grind a rough edge. for more info try youtube there are tones of diy for making

[aadhaulya]

Thanks goondasmani,

That means I should start on with the basics first. Heat treatment comes at a later stage. I wonder why the youtube did not come to my mind, maybe I am still not utilising the full potential of the internet.

Regards

Atul

[essdee1972]

Hi Atul,

I would suggest you start with a smaller blade (5-6 inches total length). This is simply because the heat treatment may work differently for a larger v/s a smaller blade with the same setup. And larger stuff usually acts funny in small furnaces.

Secondly, the steel you purchased maybe totally unsuitable for knives (since you are not aware of the grade), hence would suggest you do a full heat treat. Please don't give up if you don't get a good knife at the end. Just get a better steel and redo!

Step 1: Anneal: heat till non magnetic, air cool slowly in a closed space (no flow of air).
Step 2: Harden: heat till non magnetic, quench (used motor oil, water, etc.)
Step 3: Temper: heat till about 300-350 degrees C, hold for an hour or so, cool in the oven. (this can be done in a cake oven or microwave in convection mode).

Please do not repeat any step unless from the beginning (1, 2, 3 in order).

Heat treatment should be done only after the blade shape is cut out, bevel and rough edge is done. Although you can do the bevel and edge after HT, but the shape is better cut out before that.

You can also try with an old vehicle spring. Heat to redness, hammer to make it straight, then follow above processes. Almost all traditional and butcher knives (including khukris, daos, etc.) in India are made with spring steel.

[aadhaulya]

Thanks EssDee, for the detailed procedure. Will try to follow the steps as suggested.

Regards

Atul

[astronomy.domaine]

I would second essdee on the smaller blade size for your first attempt. There are a myriad of factors that come into play around bevel/grinding, blade proportions, cntr of gravity etc that you would only experience during a build. How these factors interplay and how small changes drastically affect the final blade form/function are much easier to understand in a smaller build.
Regarding the steel and its treatment. If you have acquired the metal from a local hardware store, it would most probably be construction grade 208 or 304 (most common)steels with very low carbon content to yield good results from heat treatment. If so, you can also try the case hardening process which works by adding carbon externally to only the outer layers of steel. Whatever the treatment approach, keep it as the final step after the cutting shaping, grinding is complete.
All the best for the build.! We all await the pics of the completed blade.!

[brihacharan]

Hi Atul,
Welcome to the band of DIY afcianados
Both essdee & AD have given you sound advice....Go ahead and create your master piece
Waiting to see the outcome
Briha

[aadhaulya]

Thank you guys for your input, The only thing bothering me is the edge of the blade. The starting of the edge up to the actual edge is quite perfect. The final sharpening of the edge is not a problem. But the I do not not think I would be able to get that perfect slope of the edge with a hand grinder, it probably requires some sort of fixture.

Kindly advise

Regards

Atul

[kshitij]

I take the shortcut and get a cycle dhaar wala to get the bevel done for me. Any knife sharpening fellow should be able to get the bevel done as per your requirement. Normally most of us get a desi version of the scandi grind i.e. one single bevel upto the edge and no secondary bevel. It is the easiest to do and keep sharp.

[aadhaulya]

I suppose that this would be the best solution. But can you get an even sharpness with one cut only. Besides, for resharpening it a secondary cut, however small, would have to be created.,

Regards

Atul

[brihacharan]

I suppose that this would be the best solution. But can you get an even sharpness with one cut only. Besides, for resharpening it a secondary cut, however small, would have to be created.,
Regards
Atul

Hi Atul,
Bevel grinding is a skill that needs to be perfected over a period of time
Both bench / belt & angle grinders can accomplish this - however the trick is in holding the blank at the requisite angle....as experimented by me a 'bench-wise' is necessary in case you're using an angle grinder as the disc spins at 11,000 rpm
In one of the videos I saw the guy had made a 'jig' using an angle iron & bolted the blank to it to get the 40* / 45* angle... this works well if you're using either a bench or belt sander.
Briha

[aadhaulya]

Briha ji,

The jig seems the only solution if one is not experienced or rather has very steady hands.
By the way, how did you get that finish on your blade. That seems to be a perfect cut.

Regards

Atul

[brihacharan]

Briha ji,

The jig seems the only solution if one is not experienced or rather has very steady hands.
By the way, how did you get that finish on your blade. That seems to be a perfect cut.
Regards
Atul

The initial rough bevel was already done by the local bicycle knife grinder....
I initially used a 4" Angle Grinder fitted with 60 grit carborundum disc & later with a 120 grit carborundum disc... The final finish was done by hand using 1000 & 1200 grit paper which was slightly moistened....
The job was done completely hand held - blade in my left & the grinder in my right - Frankly I would not recommend this method to anyone as it could be dangerous should a slip in the grip take place....
As for me I'll never ever do it again
Fortunately the end result turned out to be quite satisfactory!
Briha

[aadhaulya]

That was a really well done job.

Regards

[aadhaulya]

I would second essdee on the smaller blade size for your first attempt. There are a myriad of factors that come into play around bevel/grinding, blade proportions, cntr of gravity etc that you would only experience during a build. How these factors interplay and how small changes drastically affect the final blade form/function are much easier to understand in a smaller build.
Regarding the steel and its treatment. If you have acquired the metal from a local hardware store, it would most probably be construction grade 208 or 304 (most common)steels with very low carbon content to yield good results from heat treatment. If so, you can also try the case hardening process which works by adding carbon externally to only the outer layers of steel. Whatever the treatment approach, keep it as the final step after the cutting shaping, grinding is complete.
All the best for the build.! We all await the pics of the completed blade.!

I was looking forward to your advise. Can you tell me how does one add carbon externally,

Regards

Atul