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Author: Subject: Should I buy this furnace on ebay?
Conure
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[*] posted on 23-6-2024 at 20:41
Should I buy this furnace on ebay?


I would like a powerful hot plate since my burner isn't good enough and I found this chinese made furnace on ebay. Claims ro reach temperatures of 1200c. Too good to be true?

https://www.ebay.co.uk/itm/315398459661?chn=ps&_ul=GB&am...




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B(a)P
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[*] posted on 23-6-2024 at 21:23


I see no reason why it couldn't get that hot. The issue with this is, what happens when you inevitably get a spill? The element will very quickly get destroyed. It depends what you are trying to do with it though.
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[*] posted on 24-6-2024 at 01:25


I clicked on the link through curiosity and then on another similar looking item that Ebay suggested that only claimed 400C. Both had a spec sheet that showed the highest temperature ("heating wire"). The spec sheet (and photos) for both is identical , model numbers, power , size and all the text apart from your link shows "Highest temperature 1200C (Heating wire)" whilst the other shows "Highest temperature 400C (Heating wire)". Personally looking at the construction I'd hope that the temperature never came anywhere close to 1200C!
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[*] posted on 24-6-2024 at 04:56


Looks sketchy. It would be a much better idea to invest in a decent hotplate/stirrer that can go to a more reasonable temperature, like 400 °C.



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[*] posted on 24-6-2024 at 05:55


Should I buy this furnace on ebay?

Yes, then you can review it for others ;)

Personally, I would not buy it.
This type https://www.ebay.co.uk/itm/195704686574
was my favourite, good for many uses, no stirring.
Cheap enough to abuse until the temp. controller dies, then an external 'dimmer' makes it better than new.

I've come to value good stirring more and more,
So I like a hotplate or mantle, with stirring.




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[*] posted on 24-6-2024 at 10:55


This is not a furnace, it is a hotplate without a top. The wire may get to 1200C, but it won't be able to heat things up to more than 400C, even that is a stretch without an enclosure.
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[*] posted on 24-6-2024 at 11:36


Quote: Originally posted by B(a)P  
I see no reason why it couldn't get that hot. The issue with this is, what happens when you inevitably get a spill? The element will very quickly get destroyed. It depends what you are trying to do with it though.

My plan is to make MoO3 by thermal decomposition of ammonium molybdate. I have tried with a steel vessel over a burner and it's very a poor method because the temperature is barely high enough. So I need a more powerful heat source. Something that makes steel glow red.




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[*] posted on 24-6-2024 at 11:39


Quote: Originally posted by Texium  
Looks sketchy. It would be a much better idea to invest in a decent hotplate/stirrer that can go to a more reasonable temperature, like 400 °C.

400c is not enough for me. My steel vessel placed over a burner gets a dull red glow at the center and it's not enough practical use. I need the whole bottom to glow red.




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[*] posted on 24-6-2024 at 11:40


Quote: Originally posted by RedDwarf  
I clicked on the link through curiosity and then on another similar looking item that Ebay suggested that only claimed 400C. Both had a spec sheet that showed the highest temperature ("heating wire"). The spec sheet (and photos) for both is identical , model numbers, power , size and all the text apart from your link shows "Highest temperature 1200C (Heating wire)" whilst the other shows "Highest temperature 400C (Heating wire)". Personally looking at the construction I'd hope that the temperature never came anywhere close to 1200C!

Too good to be true then. I appreciate all your answers people.




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[*] posted on 24-6-2024 at 12:07


Electric stove element. $10
Old ss pot with lid $10
Kyle wool $50
1000w dimmer $20

You can get fancy with a pid controller off amazon.




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[*] posted on 24-6-2024 at 13:17


Quote: Originally posted by Conure  
Quote: Originally posted by Texium  
Looks sketchy. It would be a much better idea to invest in a decent hotplate/stirrer that can go to a more reasonable temperature, like 400 °C.

400c is not enough for me. My steel vessel placed over a burner gets a dull red glow at the center and it's not enough practical use. I need the whole bottom to glow red.
Then a hotplate is not the right tool for the job



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[*] posted on 24-6-2024 at 17:11


Quote: Originally posted by Conure  
I would like a powerful hot plate since my burner isn't good enough and I found this chinese made furnace on ebay. Claims ro reach temperatures of 1200c. Too good to be true?

It's more like 1200 degrees in the Rankine scale (393 °C).

Why not a charcoal furnace, like this?




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[*] posted on 24-6-2024 at 17:43


I have that exact same hot plate that I used to distill sulfuric acid and it’s the best I have ever used for that purpose. The trick is to clamp your boiling flask a few millimeters above the surface and then you can distill sulfuric acid with zero bumping! I think it’s because connective heat is so even that you don’t get the hotspots which cause bumping.
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[*] posted on 25-6-2024 at 02:21


Quote: Originally posted by Deathunter88  
I have that exact same hot plate that I used to distill sulfuric acid and it’s the best I have ever used for that purpose. The trick is to clamp your boiling flask a few millimeters above the surface and then you can distill sulfuric acid with zero bumping! I think it’s because connective heat is so even that you don’t get the hotspots which cause bumping.

Do you know how hot it gets? Enough to make stuff glow red?




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[*] posted on 29-6-2024 at 04:59


Quote: Originally posted by Conure  

400c is not enough for me. My steel vessel placed over a burner gets a dull red glow at the center and it's not enough practical use. I need the whole bottom to glow red.


If you are here, you're probably comfortable with enough with electricity to make your own to be able to heat to about 700C, hot enough for thermal decomposition and reformation into crystalline o-MoO3 in air.

For a less expensive option, you can make a simple furnace from some insulating firebrick, a standard PID controlller, solid state relay, ceramic protected type K thermocouple, and a heating element of about 500W or more (you could use a 1000W to heat a larger area if desired). I made one to do heating of a small area to about 700C-800C making manganese blue. It was made deliberately using loose firebrick to allow gasses (in my case NOx, in your case ammonia and NO) to escape and run it outdoors. It uses two bricks with carved out channels to hold the elements, one brick with the thermocouple both wired (with quick release plugs) to a controller box holding the PID controller and SSR, wired to a standard electrical cord. I just pile up bricks as needed around the heating and thermocouple bricks. I did a short write up with links to images at https://www.reddit.com/r/DIYPigments/comments/16e4jc2/commen...

EDIT corrected quote formatting

[Edited on 29-6-2024 by DrRadium]

[Edited on 29-6-2024 by DrRadium]
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[*] posted on 29-6-2024 at 06:00


Charcoal with forced air
(eg https://www.ebay.co.uk/itm/204819849468)
will get steel orange hot, easily melt aluminium etc.




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[*] posted on 29-6-2024 at 11:37


Quote: Originally posted by Conure  
Quote: Originally posted by Deathunter88  
I have that exact same hot plate that I used to distill sulfuric acid and it’s the best I have ever used for that purpose. The trick is to clamp your boiling flask a few millimeters above the surface and then you can distill sulfuric acid with zero bumping! I think it’s because connective heat is so even that you don’t get the hotspots which cause bumping.

Do you know how hot it gets? Enough to make stuff glow red?


You can get a steel crucible sitting directly on the element to a dull red, but certainly not enough to melt metals (it does soften aluminum but not hot enough to get it fluid enough to cast).
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[*] posted on 5-7-2024 at 16:33


I am proud to say that I improvised my own furnace. I needed to de-temper a cast metal weight lifting plate in order to render it soft enough, to easily machine.

I simply placed the plate on one of my Electric Range-top elements, and then placed an inverted cast-iron frying pan over the top of the whole thing to contain the heat. This seems to have worked; but I'm not sure.

Of certainty though, is that this experiment quickly burned out the heating element, and also the temperature control switch.

Thereafter, cooking at my house, became much more difficult.

Eventually, I broke down and invested in some Tungsten Carbide drill bits. It circumvented my machining problems.

And, over time, I have, sort of, rehabilitated my kitchen stove. Oh, it will never again be the valiant creature that it once was; but it will make do, until the next girlfriend arrives. And then of course, I will have to buy a new stove.
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