Any interest in making an induction heater for melting metal /high-temp chemistry?

Science
#21

Not a bad idea, some of the factories that cast parts imbed a bolt or other piece of hardware that is used for handling the wax as it is being invested, then use an induction heater to warm the bolt just enough that it melts through the wax and falls out.

My problem would be getting all the metal filings out of the mold. Some would probably cling to the very inside even when all the wax vaporized and might do something unusual to the surface of the jewelry. I might try it once to see, though. No telling, it might look really attractive.

#22

Bismuth can be melted in a kitchen pan. About 600f degrees to melt it. Easy peasy.

I have been looking for a tall narrow pan at 2nd hand stores. No joy yet.

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#23

Yes, I know it can be melted in a pan, but if you want the really outstanding crystals, need to heat well above the melting point, cool very slowly to supercool well below the freezing point, then ideally nucleate with small crystals. Pan and blowtorch do not lend themselves to even heating or slow uniform cooling, nor to control of oxidation. Need oxidation to get the pretty colors, but too much and there is excessive nucleation (many small crystals instead of few biggies). Also know there is some way to guide the shape to get large pyramids, but do not know what the trick is.

#24

Tall-form pyrex beaker softens at 820 degrees C, 1510 degrees F. 700C is quite stable.

https://www.amazon.com/PYREX-Berzelius-100mL-Beaker-Graduated/dp/B006JGQFJY/ref=sr_1_2?ie=UTF8&qid=1502484537&sr=8-2&keywords=tall-form+pyrex+beaker

Not hot enough for jewelry metals but more than hot enough for bismuth. Thought of wrapping a beaker in insulation then putting it inside induction coil. (hold top with tongs). Mr. Terrence thinks graphite crucible too fragile, also graphite itself is conductive, has susceptibility to RF induction.

#25

wonder what would happen if used low melting metal for filings, like wolfs metal (melts in boiling water). You are probably right there would still be some sort of residue, no telling how it would interact with jewelry metal. Might be appealing, as you say, or at least interesting.

#26

Pyrex test tubes might make a good test of this approach if you want to try it. My current coil has an inside diameter of a little over an inch, so a large test tube would be a good fit.

#27

The coil in your picture looks much bigger than an inch.
The rebar has lots of space around it.
So you replaced it with a smaller coil?
a test tube would give very small amount of melted material, and very small crystals.

Does anyone have an IR non-contact type thermometer to measure temp?
Would be very handy. Have them at harbor freight for $30.

#28

FYI, most non contact infrared guns only go to about 6-650*. Just so you know.

#29

Yes, I replaced with a smaller coil. The idea of the test tube is to determine how effective it will be melting the bismuth.

Steels seem very effective, but brass much less so.

#30

Oh I did not know that. So no way to know how hot that glowing rebar was? certainly hotter than 650. What would be the best way to check temperature? Thermocouple? Thought temp could be regulated by just inserting and removing item from coil, but need some way to know the temp.
wanted to use lots of insulation around heat vessel. I realize that a bigger coil (to accomodate insulation) results in a less intense field and slower heating, (heating proportional to square of mag field), but figure less heat loss would more than make up for weaker magnetic field.

#31

Yes, anything magnetic like steel will heat primarily by hysteresis loss, nonmagnetic materials like brass will heat only by eddy currents so much slower. Not sure what a diamagnetic like Bismuth will do, but I am guessing no better than brass.

#32

High temp infrared guns are not cheap.

https://www.amazon.com/Taotuo-Non-contact-Temperature-Thermometer-58-2912/dp/B00PEHCYBW/ref=sr_1_5?ie=UTF8&qid=1502506609&sr=8-5&keywords=high+temperature+thermometer

#33

I have a gun rated to 350 deg C

#34

Have 1 of these on the wish list:

#35

That’s actually cheaper than the ones we were looking at the other day. They were 3-5,000$. But they were rated to about 4000 degrees f.

#36

Nice gun but $800? can find other guns in that temp range or higher for much less. Am I missing something? What did you want to use the gun for?

#37

Mouser made a very generous donation to the ELab last year and asked for a list for this year.
Top of the list was types of gear the ELab doesn’t have and requests made during the past year.
Mouser carries a broad line of Fluke gear, so why not ask?

1 Like
#38

Very smart. Fluke is top quality. If they will go for it, then as you say, why not.
I was curious how electronics would use a thermometer.

#39

Very useful for diagnosing problems in modern boards. Heat sources can help localize problems.

2 Likes
#40

I have one that goes up to 3000 Degrees. That should cover most of our needs.