Mini electric kiln project

[Jan]

Mr. Wadebevan and Mr. Mark thank you very much for answering my questions and sharing your recipes.  

I am complementing it with domestic practices and also with recommendation from various steel data sheets. I have decided to start my hardening experiments with carbon steel because hardening temperature is significantly lower compared with stainless steel.

Jan

[Jan]

I have finally received the high temp. thermocouple and have started its calibration/checking using an old mercury thermometer which works up to 1150°F.

         

Jan

[EOU]

Does your thermocouple come with a published calibration curve Jan and can you program that curve into your controller?

[Jan]

The thermocouple did not come with calibration curve, it is so called K type sensor and the PID controller is preprogramed for some 10 different sensor types. I can change an additive constant only.

Jan

[Jan]

The thermocouple has been finally calibrated and so I was able to harden my first blade!

I bought inexpensive Thyssen Krupp billet bar steel 80CrV2, which is carbon spring steel used in Finish knife industry.

   

Hardness of the annealed billet was circa 40 HRC. After 10 min hardening at 1545°F and oil quenching the blade hardness was between 60 and 65 HRC.

After 2 hours tempering at 390°F the hardness dropped slightly below 60 HRC.

   

The blade has flat Scandi grind with included angle of 24°and a microbevel with 34°. The handle was made of ash wood and still has to be impregnated.

Jan

[Rupert Lucius]

Awesome

Thanks for the update.

Rupert

[grepper]

Sure turned out pretty Mr. Jan. Congratulations! Did you make the handle?

How are you testing hardness?

[Jan]

Mr. Ruppert and Mr. Grepper thanks for your kind words, it is only my apprentice work, U3A (University of the Third Age).  

The handle is my own product also. It was made from two thin ash wood plates. In the middle I routed a groove for the tang.

   

My knife making equipment is really humble. For both, the blade and the handle, I use a belt sander with Tormek universal support bar mounted on a wooden platform. The knife jig slides sideways on the support bar and guarantees consistent bevel angle along the straight part of the blade.

       

For raw estimation of blade hardness I use hardness testing file set (40 to 65 HRC).


Jan

[scott.livesey]

nice job. I like your belt sander angle control. 80CrV2 is good steel. I have used it at Rc62-63, it will take a very thin edge and not chip.
scott

[Jan]

Mr. Scott, thanks for your assurance that steel 80CrV2 was the right choice for my experimenting. I can confirm, that compared to stainless steels I usually sharpen, 80CrV2 was easier to sharpen and deburr.
 
Next on my list is tool steel O1 (1.2510/100MnCrW4).

Jan