goodies from down south

[marthandan]

had visited my native place madurai. there is a village closeby that is known for its blacksmiths. they will make anything you ask for, especially when you share a good relationship with them and picked up these goodies
the top one is a kukri blank made to my design. the middle one is a "veech aruval' and the third one is an aruval/ sickle for home use. the kukri blank is about 18" long.

DSC02334.JPG

plan to start working on the kukri blank first

DSC02329.JPG

[varunik]

Veech aruval lloks good

[Priyan]

Do they heat treat the blade properly? Here local blacksmiths just forge and quench in water resulting in a hit or miss quality.

[marthandan]

Do they heat treat the blade properly? Here local black

it depends on the individual. some do it properly (checking with a magnet). others just heat to red and quench.
one guy even quenched it the other way round....the spine was yellow with a spring temper (blue colored) edge.

[Moin.]

Very nice

Any specific reason for having the clip point on the Khuk Blank ?

P.S: You raise an intersting point. I once saw a video on how Japanses Katana's are forged and tempered. Although teh forging etc is a complex art in itself, the blades were quenched in water, but due to the adding of the clay coating in the distinctive hammon pattern the portions of the blade cool at different speeds and thus the difference on the hardness.

Should be interesting to know what the correct way to temper is and what is done by Sakligars in Rajasthan. Maybe Katanji or Rajat can throw some light on this.

What is thw correct way to temper, what is the temperature the steel is to be heated to, how do you avoid steel become britlle ?

Lastly do the knifes made from leaf springs or circular saw blades or files are required to be tempered ? Like traditional billets these do not go extensive forging to be brought in shape and the steels are modern tool steels ( for file & saw blades)
Regards
Moin.

[Priyan]

Dear Moin,
I'm not a metallurgist but AFAIK heat treatment of knives is a three step process. After forging, the blade is normalized by heating the blade till it's nonmagnetic and then letting it air cool. This step removes stresses in the metal introduced by the forging process.

After that the hardening process starts, in this step the previously normalized blade is heated till its nonmagnetic, and then quenched in motor oil which is preheated to about 50°C. This hardens the blade to give it more strength.

Then the blade is cleaned to remove the baked oil that sticks to the knife in the quenching process. Now the back of the blade is tempered by the help of a torch. The cutting edge is covered with a damp rag and the blade is clamped in a vise. The torch is applied to the back of the knife until you see the desired color. The colors indicate different levels of hardness, the colors are straw, light yellow, yellow, light brown, dark brown, red, purple, blue, gunmetal gray. Straw is the hardest one can draw on a blade without stressing it. Gunmetal gray is the softest of all and some people prefer it for 'all around' knives. My personal favorite for survival knives is light yellow but a lot of people prefers blue. I haven't made a lot of kitchen knives to have a preference but I either draw it to blue or straw.

Speaking of Japanese Katanas' heat treatment process, I'm planning try it on a knife and will post the results here.

Yes, knives made from leaf springs and bandsaw blades need heat treatment as the cutting and forging introduces stress in them as I already mentioned. They'll have to be normalized first then hardened and tempered as mentioned. Also files are very hard and brittle so its hard to make knives out of them without annealing them first.

I've been very silent about my knife making on IFG, I'll try to post about this subject more often from now on.

[marthandan]

Any specific reason for having the clip point on the Khuk Blank ?

when the bevels of a knife are forged, the tip turns upwards. that part will not form a part of the final knife and has already been cut off. will post pics tomorrow.

and as far as i know (which is quite little), priyan has got it spot on regarding the heat treatment of blades. i use a charcoal furnace to normalize, anneal or harden my blades. quenching is done in room temperature mineral oil (mostly bran oil and coconut oil (plan to use water for the kukri). tempering is done using my mom's baking oven. it might not be very accurate. but i have got good results using it (the kirdashi was tempered in the oven).

Speaking of Japanese Katanas' heat treatment process, I'm planning try it on a knife and will post the results here.

what do you plan to use as clay? tried pure clay. it just fell off while heating in the furnace. had prepared the clay well. so that was not the issue.

[Priyan]

Dear marthandan,
The clay used by the potters here doesn't fall off as long as you prepare it properly. I can get this clay in a nearby river but I'll have to wait till winter for the river to dry up. Also the black soil that comes out while boring tube well works too. BTW if you put it in the furnace while the clay is wet it tends to warp the blade, also the clay has a higher chance of falling off. I don't know much about this clay method of tempering and can't find much on internet either. I guess I'll have to follow the "trial and error" route.

[rraju2805]

Very nice kukris. . .

I had a very little experience about the process to make those ,i won it During my maduri trip. . .

[Moin.]

Dear Moin,
I'm not a metallurgist but AFAIK heat treatment of knives is a three step process. After forging, the blade is normalized by heating the blade till it's nonmagnetic and then letting it air cool. This step removes stresses in the metal introduced by the forging process.

After that the hardening process starts, in this step the previously normalized blade is heated till its nonmagnetic, and then quenched in motor oil which is preheated to about 50°C. This hardens the blade to give it more strength.

Then the blade is cleaned to remove the baked oil that sticks to the knife in the quenching process. Now the back of the blade is tempered by the help of a torch. The cutting edge is covered with a damp rag and the blade is clamped in a vise. The torch is applied to the back of the knife until you see the desired color. The colors indicate different levels of hardness, the colors are straw, light yellow, yellow, light brown, dark brown, red, purple, blue, gunmetal gray. Straw is the hardest one can draw on a blade without stressing it. Gunmetal gray is the softest of all and some people prefer it for 'all around' knives. My personal favorite for survival knives is light yellow but a lot of people prefers blue. I haven't made a lot of kitchen knives to have a preference but I either draw it to blue or straw.

Speaking of Japanese Katanas' heat treatment process, I'm planning try it on a knife and will post the results here.

Yes, knives made from leaf springs and bandsaw blades need heat treatment as the cutting and forging introduces stress in them as I already mentioned. They'll have to be normalized first then hardened and tempered as mentioned. Also files are very hard and brittle so its hard to make knives out of them without annealing them first.

I've been very silent about my knife making on IFG, I'll try to post about this subject more often from now on.

Dear Priyan;

Thanks a lot, this is very very good info.Please post lots and lots of pic if and when possible.. Good times in IFG, discussing tempering of blades, differential heat treatments.....

Regards
Moin.

[timmy]

marthandan, without wanting to be nosy, could you give me an idea how much blades like the ones you've shown can be obtained for?

[essdee1972]

Priyan, spot on with the process!!!! (Having a degree in metallurgy just gives you the theory part, so you know what happens to the atoms and molecules, the practice you have to do it by trial and error!!)

Actually the best knives and precision tools are done individually as described by Priyan (the ads would call them hand made, hand forged, etc, and charge 5 times the $$). Probably the big shots would use electronic thermometers and temp comtrollers, however the basic proces remains the same.

For the mass manufactured stuff (say common kitchen knives), batch process is used where the annealing, hardening and tempering are done to hundreds and thousands of pieces at a time. With the result that you don't get differential edge and spine hardness in most of the mass produced stuff.

The important process here is the tempering. Annealing and hardening CAN be done in mass production fashion, without much damage to the quality. In the tempering, the differential temper can be obtained only when the back (spine) and edge are heated to different temperatures and cooled at different rates. We used to do a similar process to gear blanks when I actually worked as a metallurgist for 2 years (15 years back). We would place the blanks in the furnace in such a way that the part which should end up being softer is closer to the flame (just like applying the torch flame to the spine of the knife), and the other part, destined to be harder, would be stuck in cavities made for the purpose. In some cases, we actually had some kind of oils running in pipes below the cavities to keep the temperatures down (akin to the wet cloth used to clamp). The furnaces were the conveyor type with timers and temp controllers and other widgets.

The leaf spring knives, if shaped by hand filing, might do without heat treatment (unless you want the differential hardness / strength). When you cut / shape it on a electrical saw running at a few thousand rpm, a lot of heat is generated, which leads to inadvertent heat treatment (have you noticed the bluish tinge when you drill through steel?). This needs to be corrected, hence the requirement of proper HT. Since you don't really know exactly what the high-speed machine has done to the steel, it's better to do the whole A-H-T cycle, rather than try to correct localised inconsistencies. For band saw blades, they are quite brittle (one of my hobbies when working in the steel industry was to grind knives out of broken band saw blades), as the HT done to them is not the same as for knives. Plus the grinding into shape does something to the internal structure. Ergo, heat treatment!

By the way, I found the box where my 16 year old books were kept, while doing spring cleaning last weekend. Unless the termites have got to them, I'll try to get some theory online shortly. Have to revise the austenites and martensites!! I think you can also find resources online where heat treatment temperatures, times, etc. would be available. And maybe you can invest in a remote thermograph or something (probably a few thousand bucks).

Moin, doesn't this make you feel like selling this tiny Mumbai apartment, and setting up a home (with attached metal works) in a smaller town?? If I try heat treatment in my flat, the neighbours would probably call the cops!! And you'll see my pic in the papers as the next terrorist in town...

Enjoy!

[dr.jayakumar]

dear Martha,
what handle did you fix foe veech aruval?i have one fixed with a bulls horn.
regards
dr.jk

[Moin.]

Priyan, spot on with the process!!!! (Having a degree in metallurgy just gives you the theory part, so you know what happens to the atoms and molecules, the practice you have to do it by trial and error!!)

Actually the best knives and precision tools are done individually as described by Priyan (the ads would call them hand made, hand forged, etc, and charge 5 times the $$). Probably the big shots would use electronic thermometers and temp comtrollers, however the basic proces remains the same.

For the mass manufactured stuff (say common kitchen knives), batch process is used where the annealing, hardening and tempering are done to hundreds and thousands of pieces at a time. With the result that you don't get differential edge and spine hardness in most of the mass produced stuff.

The important process here is the tempering. Annealing and hardening CAN be done in mass production fashion, without much damage to the quality. In the tempering, the differential temper can be obtained only when the back (spine) and edge are heated to different temperatures and cooled at different rates. We used to do a similar process to gear blanks when I actually worked as a metallurgist for 2 years (15 years back). We would place the blanks in the furnace in such a way that the part which should end up being softer is closer to the flame (just like applying the torch flame to the spine of the knife), and the other part, destined to be harder, would be stuck in cavities made for the purpose. In some cases, we actually had some kind of oils running in pipes below the cavities to keep the temperatures down (akin to the wet cloth used to clamp). The furnaces were the conveyor type with timers and temp controllers and other widgets.

The leaf spring knives, if shaped by hand filing, might do without heat treatment (unless you want the differential hardness / strength). When you cut / shape it on a electrical saw running at a few thousand rpm, a lot of heat is generated, which leads to inadvertent heat treatment (have you noticed the bluish tinge when you drill through steel?). This needs to be corrected, hence the requirement of proper HT. Since you don't really know exactly what the high-speed machine has done to the steel, it's better to do the whole A-H-T cycle, rather than try to correct localised inconsistencies. For band saw blades, they are quite brittle (one of my hobbies when working in the steel industry was to grind knives out of broken band saw blades), as the HT done to them is not the same as for knives. Plus the grinding into shape does something to the internal structure. Ergo, heat treatment!

By the way, I found the box where my 16 year old books were kept, while doing spring cleaning last weekend. Unless the termites have got to them, I'll try to get some theory online shortly. Have to revise the austenites and martensites!! I think you can also find resources online where heat treatment temperatures, times, etc. would be available. And maybe you can invest in a remote thermograph or something (probably a few thousand bucks).

Moin, doesn't this make you feel like selling this tiny Mumbai apartment, and setting up a home (with attached metal works) in a smaller town?? If I try heat treatment in my flat, the neighbours would probably call the cops!! And you'll see my pic in the papers as the next terrorist in town...

Enjoy!

Great Info, Essdee.

You said it, I stay in a 400 sq.ft apartment, can't do a thing without my mother india acting nosy and the pesky neighbours complaining.

Regards
Moin

[Moin.]

Any specific reason for having the clip point on the Khuk Blank ?

when the bevels of a knife are forged, the tip turns upwards. that part will not form a part of the final knife and has already been cut off. will post pics tomorrow.

and as far as i know (which is quite little), priyan has got it spot on regarding the heat treatment of blades. i use a charcoal furnace to normalize, anneal or harden my blades. quenching is done in room temperature mineral oil (mostly bran oil and coconut oil (plan to use water for the kukri). tempering is done using my mom's baking oven. it might not be very accurate. but i have got good results using it (the kirdashi was tempered in the oven).

Speaking of Japanese Katanas' heat treatment process, I'm planning try it on a knife and will post the results here.

what do you plan to use as clay? tried pure clay. it just fell off while heating in the furnace. had prepared the clay well. so that was not the issue.

Great... Just a though, why not try plaster of paris instead of clay, should resist heat to a great extent,easily available, hardens nocely, easy to remove...

Regards
Moin.