Heating element for very small high temp oven

[3v0]

If possible I would like to build a small electric temperature controlled oven with a working interior space of 2" by 2" by 6", am flexible here but a small cavity is easier to heat; The control part is standard stuff. I am wondering if anyone knows of a heating element that would be more convenient that kanthal resistance wire.

The idea is to make a little oven to braze HSS high speed steel to common steel. The brazing temperature and where the HSS looses its temper is very small. Too small to be done with a torch.

This is more of an experiment then anything else. I have the temperature control parts and firebrick. Just wondering about the easiest way to heat it.
20 seconds at 18:50 in this video is the inspiration.

 

[dknguyen]

Why not experiment with the induction heater mentioned in the video? Are they difficult to build? Because I would totally try that. Or IR but that feels harder.

I know nothing of the subject but my gut feel is that air is such a crappy thermal conductor that it would be impractical, even if it was directed hot air.

 

[MaxHeadRoom78]

Google Royer HF circuits, https://kaizerpowerelectronics.dk/general-electronics/royer-induction-heater/
Max.

 

[kubeek]

I think standard heating wire like kanthal is good enough. You can make the kiln out of ytong bricks and use a K thermocouple to measure the temperature.

 

[shortbus=]

When still working (tool and die maker) when we needed to do this, we used Tig with a silicon bronze filler rod. If I remember correctly it needs to be preheated(after fixturing the two parts) to around 700 - 800 degrees F.

 

[3v0]

I think standard heating wire like kanthal is good enough. You can make the kiln out of ytong bricks and use a K thermocouple to measure the temperature.

ytong blocks sound wonderful and CHEAP. But sadly a short look see on the web does not show them for sale in the US.

 

[3v0]

When still working (tool and die maker) when we needed to do this, we used Tig with a silicon bronze filler rod. If I remember correctly it needs to be preheated(after fixturing the two parts) to around 700 - 800 degrees F.

My point in trying to braze in an oven is to precisely control the temperature so as to not ruin the temper. Using a tig which I don't have would sort of do an end run around the experiment. But thanks for the insight just the same

 

[kubeek]

ytong blocks sound wonderful and CHEAP. But sadly a short look see on the web does not show them for sale in the US.

Well if you can´t get those, then you can use refractory bricks or glass fiber mats.

 

[shortbus=]

My point in trying to braze in an oven is to precisely control the temperature so as to not ruin the temper. Using a tig which I don't have would sort of do an end run around the experiment. But thanks for the insight just the same

Hi, the Tig/silicon bronze does preserve the HSS temper.

Can I ask what you are trying to make with your "experiment"? A mill cutter? A boring bar? There are low temperature silver solders and 'silver bearing' solders that are fairly high strength, and if the shank is designed correctly (support of the HSS tip) may do the job for you.

 

[3v0]

Well if you can´t get those, then you can use refractory bricks or glass fiber mats.

Of course but at a much higher price.

 

[3v0]

Hi, the Tig/silicon bronze does preserve the HSS temper.

Can I ask what you are trying to make with your "experiment"? A mill cutter? A boring bar? There are low temperature silver solders and 'silver bearing' solders that are fairly high strength, and if the shank is designed correctly (support of the HSS tip) may do the job for you.

Nothing specific. An acquaintance just recently did it, as you suggested with silver solder and a propane torch
Which is an even better solution. So no point in this oven.

 

[kubeek]

I found prices around 3-5 USD for a fire brick 9x4.5x2.5", you would need I guess five of those to make a kiln for a single tool. Doesn´t look that pricey.

 

[3v0]

I found prices around 3-5 USD for a fire brick 9x4.5x2.5", you would need I guess five of those to make a kiln for a single tool. Doesn´t look that pricey.

I imagine there were hard fire brick. Soft insulating bricks are more expensive. $15 to $20

https://www.amazon.com/GREENTHERM-I...TF8&qid=1529375998&sr=8-10&keywords=firebrick

 

[shortbus=]

I imagine there were hard fire brick. Soft insulating bricks are more expensive

Do you have a "Family Farm and Home" in your area? They carry the soft fire brick. **broken link removed**