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Peter.
06-20-2010, 11:37 AM
Has anyone here dabbled in DIY induction-heating? I'd like to hear of anyone who has successfully (or un-successfully) tried this.

I have an idea that requires the heating of the end of thin-walled steel tube to silver soldering temperatures. Typically the last 25mm of a 100mm tube of 2-3mm wall thickness but diameters will vary. Needs to be a fairly portable rig and temperature control can be as crude as an on-off foot switch. If it would be possible with 3KW of power then all the better.

lazlo
06-20-2010, 11:53 AM
It's relatively straightforward to heat up a part with an oscillating magnetic flux -- there are dozens of them on Youtube.

It's much, much harder to do it practically (with an adaptive resonant circuit). This guy used a PLL chip, but as you can see, the setup is not trivial:

http://www.youtube.com/user/kynaniska83#p/u/4/-y9whTDieTk
http://www.youtube.com/watch?v=yXq2yls8IRY

Buried in one of the video descriptions he's got a link to his web page where he describes the circuit design.

small.planes
06-20-2010, 12:41 PM
try posting a ping on usenet group uk.rec.models.engineering for Andrew Mawson. He has an induction setup that he built. He is somewhere down south in the uk.
Dave

Herm Williams
06-20-2010, 01:04 PM
I am interested in a small unit too. I would like to use hi power mosfet driving scr for the power but lack knowledge to design the circuit. I have spare 20 amp 1 kv mosfet's if someone would care to share (trade info for hardware) diagrams.
re

Peter.
06-20-2010, 01:32 PM
It's relatively straightforward to heat up a part with an oscillating magnetic flux -- there are dozens of them on Youtube.

It's much, much harder to do it practically (with an adaptive resonant circuit). This guy used a PLL chip, but as you can see, the setup is not trivial:

http://www.youtube.com/user/kynaniska83#p/u/4/-y9whTDieTk
.

You're not kidding - looks like enough gear to split the atom. Surely the same must be possible by a much more basic path - even if it's less efficient.

Dave thanks for the reference I'll do a search on Google groups.

Willy
06-20-2010, 01:55 PM
Peter I posted a thread a couple of years ago looking for info on the feasibility of a DIY induction heater.

http://bbs.homeshopmachinist.net/showthread.php?t=26941&highlight

There seems to be a lot of interest in the subject as the thread has well over 12,000 views to date but not too much for viable solutions.
I'll be watching your thread with interest as I'm sure others will as well.
Hopefully someone has a workable unit that can be built without a degree in high frequency electronics.

Ries
06-20-2010, 04:19 PM
This comes up from time to time, and the answer is that to do it right, its not easy or cheap.

It is comparable to building your own Tig welder with High Frequency, or making your own overhead cam V8 engine.

Both are certainly POSSIBLE in a home shop, and both have rarely, very rarely, been done by individuals on a shoestring budget.

here is a long discussion of the subject, with a variety of links to working models and maybe not-so-working ones.

http://bbs.homeshopmachinist.net/showthread.php?t=37861

Rich Carlstedt
06-20-2010, 04:37 PM
You fellows should go visit your local auto repair shop, or a muffler shop.
Snap-on Tools already has such a unit.

Its portable , about the size of a Saws-All and is used for stuck nuts.
The induction coil (different sizes) is placed around the nut like you would a wrench, and the trigger pulled. After 10 to 15 seconds the nut will glow red to yellow and you spin it off. They use to torch them off, but that is dangerous around a gas tank...

Rich

RWO
06-20-2010, 04:44 PM
It would be much easier to simply resistance heat it. Almost any welding machine should be able to put out enough current to heat it up. Simple spring-loaded copper block contacts machined to fit a short section of the OD of the tube, one on each side, and turn on the current.

RWO

Peter.
06-20-2010, 04:45 PM
I've clocked one of them on eBay Rich, looks like the perfect tool for bolt heating but I think I need more power than that unit would produce. There's also a nice 4KW unit on canadian eBay which would be handy because they use the same mains voltage as us but at 2.5k it's a bit much for an experiment.

jkopel
06-20-2010, 04:49 PM
I just ran across this the other day.
He has a relatively simple setup mainly for experimenting with.
The kits look pretty reasonable, but don't expect to melt a lot with it.
http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat8.html

macona
06-20-2010, 05:53 PM
I just ran across this the other day.
He has a relatively simple setup mainly for experimenting with.
The kits look pretty reasonable, but don't expect to melt a lot with it.
http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat8.html

That was on hackaday a couple weeks ago. I friend is going to build one for melting samples in a vacuum.

http://hackaday.com/2010/06/04/1000w-induction-heater/

Willy
06-20-2010, 06:52 PM
I've clocked one of them on eBay Rich, looks like the perfect tool for bolt heating but I think I need more power than that unit would produce. There's also a nice 4KW unit on canadian eBay which would be handy because they use the same mains voltage as us but at 2.5k it's a bit much for an experiment.


Peter, Canada And US mains voltages are similar, both of course differ from the UK. Just for your info should you come across something from another country have a look at this chart for compatibility.


http://www.gbaudio.co.uk/data/mains.htm

T3sl4
11-24-2010, 10:20 PM
Hello,

I found this thread while Googling and thought I'd drop by. This is my project and stuff, thanks for looking. If anyone has any questions, I'll be glad to answer them.

I started a new website here: http://www.williamsinduction.com/ it's just getting started, not much up yet.

Tim

Dunc
11-25-2010, 08:55 AM
RWO wrote:
"... easier to simply resistance heat it. Almost any welding machine should be able to put out enough current to heat... "

Wasn't the AC buzz box equipped with a carbon arc torch the "old way" to do this? Hook the torch to the machine and things got hot in very short order. The way I recall it being used the arc-flame created by the torch was used although I think that it could also have been used by placing the slightly spaced carbon rods in direct contact with the metal (frozen nut, for eg). In the latter case, I don't think this would have produced much of a flame: merely localized red heat.

That said, I wonder if the currently manufactured AC welders (thinking 220 volt, 225 amp) machines are up to this type of use? Windings especially? Afaik the arc torch used only 40 amps or so.

Are these torches and their carbon rod fuel still available? Lincoln used to sell one.

wierdscience
11-25-2010, 10:16 AM
You fellows should go visit your local auto repair shop, or a muffler shop.
Snap-on Tools already has such a unit.

Its portable , about the size of a Saws-All and is used for stuck nuts.
The induction coil (different sizes) is placed around the nut like you would a wrench, and the trigger pulled. After 10 to 15 seconds the nut will glow red to yellow and you spin it off. They use to torch them off, but that is dangerous around a gas tank...

Rich

Gee thanks Rich,one more tool I must have!:D

http://www.theinductor.com/index.php?m=41

I see them for $550,that's not bad at all for what it does.Small parts heat treating in the HS should be doable too.

davidh
11-25-2010, 10:42 AM
check this place. i have a 2500 watt unit with twin carbon pliers. the wow factor start right now. i use it for heating brass battery terminals for soldering them to the cable. i've silver soldered with it many times. foot switch, on / off control. might be a tad spendy. i think i paid 750 or so US,. a fedw years ago.

www.americanbeautytools.com

lazlo
11-25-2010, 11:44 AM
I started a new website here: http://www.williamsinduction.com/ it's just getting started, not much up yet.

Tim, commercial advertising is not allowed here.

Deja Vu
11-25-2010, 02:19 PM
Tim, commercial advertising is not allowed here.

Okay, I'll do it for him then...
http://www.williamsinduction.com/

the above site gives you information on the subject.


Geeesh....

lazlo
11-25-2010, 03:01 PM
the above site gives you information on the subject.

Geeesh....

It does? Where? All I see is "Products" which is Tim selling his induction heater kit.


"This venture has its origins in 2003, when I started researching induction heating. At this time, I wanted to melt iron in my home made, propane fired furnace, but didn't want to spend the expensive amount of fuel required to do so if it was even possible to reach such temperatures. Induction heating has practically unlimited temperature, and electricity is very cheap, the logical choice.

Since then, I have developed a proven design for an induction heater of useful power output the 1kW model. Since 2010, I've been selling plans, kits and completed units online."

masimec
11-25-2010, 04:28 PM
Can you heat bearings on a induction cooktop like that??? : http://cgi.ebay.com/NEW-Max-Burton-6000-Induction-Cooktop-110V-UL-FastShip-/260650892010?pt=US_Cooktops&hash=item3cb000faea

thanks,

Martin

T3sl4
11-26-2010, 12:21 AM
Tim, commercial advertising is not allowed here.
Oops, good point. I suppose it does no good to remove it now that the cat's out of the bag...

Anyway, questions or comments -- I realize my website may be a bit technical, so if you're confused or wondering about something, don't hesitate.

Tim