# Induction Heater



## WDG (Aug 20, 2017)

Does anyone have a real good way to make a cheap induction bearing heater?  I've been on youtube and have watched a few but I wasn't real fond of what they put together.  Usually talking over my head in electronics.  Although and E&I tech I'm not a component man so making a choke and other things isn't what I want.  I think the transformer from a microwave is the best what I would like to know is if anyone has first hand knowledge?


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## Ulma Doctor (Aug 20, 2017)

i wish i knew something about them , i too would like to learn about induction heaters.
i have seen them and used them, but i'm not exactly sure how they work.
i'm envisioning that you are short circuiting a heavy transformer's secondary circuit with a semi resistant metal that the bearing is supported on.
the resistance creates heat that warms the bar and bearing.
the input voltage, the transformer VA rating, the secondary voltage and the warming bar's resistance will dictate the potential of heat induction capabilities.
if you could vary the output, that'd be sweet!


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## Tony Wells (Aug 20, 2017)

The object being warmed is the secondary, and the eddy currents developed in it amount to a direct short, thus warming up said object.  That's why they only work on conductive materials, with ferrous being the foremost.

Of course, there's more to it than that oversimplified statement, and it is interesting how they work. Totally practical for the home shop. Interesting build project.


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## British Steel (Aug 20, 2017)

How about a worktop induction hob from the charity shop, I'd expect it to work well as it does the same job on pots and pans?

Dave H. (the other one)


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## brino (Aug 20, 2017)

I have not used one, but did see some on ebay after a discussion here.
Someone was asking about one for localized heating for rusted bolt/nut removal.

http://www.ebay.ca/itm/1000W-ZVS-Lo...805772?hash=item1c683b5f4c:g:aiwAAOSw5cNYmTqI

http://www.ebay.ca/itm/20A-ZVS-Indu...936570?hash=item41c7ade4fa:g:SscAAOSwjKFZO7J2

(I have no interest in those sellers, just grabbed two random vendors!)
The pictures on those two look really interesting.

I'd like to hear some first hand experience if anyone has tried one.

-brino


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## woodchucker (Aug 20, 2017)

I've been using a coffee mug warmer to get my bearings to fit over shafts.  Works pretty good, I need gloves to pick them up. Of course we are talking bearings smaller than a coffee mug.. Not huge honkers.


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## brino (Aug 20, 2017)

a couple related threads........

an induction heater in action:
http://www.hobby-machinist.com/threads/this-is-just-cool-not-practical-just-cool.58160/

a request for plans from Jan 2016 that had ZERO replies......
http://www.hobby-machinist.com/threads/induction-heater-plans-wanted.42443/
...that doesn't happen much on this site!

-brino


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## Wreck™Wreck (Aug 20, 2017)

WDG said:


> Does anyone have a real good way to make a cheap induction bearing heater?  I've been on youtube and have watched a few but I wasn't real fond of what they put together.  Usually talking over my head in electronics.  Although and E&I tech I'm not a component man so making a choke and other things isn't what I want.  I think the transformer from a microwave is the best what I would like to know is if anyone has first hand knowledge?


This is a thing of beauty, carry on.


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## Billh50 (Aug 21, 2017)

Here's a link about making one. They also sell ready made parts for one.
http://www.rmcybernetics.com/projects/DIY_Devices/diy-induction-heater.htm


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## brino (Aug 21, 2017)

Billh50 said:


> Here's a link about making one.



Bill -Thanks for that link!
What a simple circuit, low parts count, and very tweak-able.....and even gives a spice circuit simulation file.

Another project added to the list!
-brino


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## TRX (Aug 21, 2017)

I bought one of the $35 induction heaters from eBay.

Be aware that all you get is the circuit board and the copper coil.  I spent another $150+ buying a power supply, a water pump, silicone hoses, proper clamps for the hoses, connectors for the inductor cables, a small radiator, fans, a motorcycle brake reservoir to use as a fill point, and some stuff I didn't *really* need - ammeter, voltmeter, water temp gauge, a high-temp laser thermometer to measure how hot the workpieces get, and a small crucible and tong kit to use for melting metals.

I was going to use an old computer case to package all the bits in, but I threw out all the junk in the storage room a while back, so I'm waiting until a freebie comes along.


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## brino (Aug 21, 2017)

TRX said:


> I bought one of the $35 induction heaters from eBay.



Okay thanks guinea pig, er.... I mean....... @TRX. 
Please let us know how it works out for you!

-brino


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