Page 4 of 4 FirstFirst ... 234
Results 31 to 40 of 40

Thread: DIY induction heater

  1. #31
    Join Date
    May 2006
    Location
    Grimsby... 51state of the USA
    Posts
    891

    Default

    Quote Originally Posted by boslab View Post
    I haven't been thinking much about induction heaters until I needed to change some big bearings and needed to heat them, at work we had a bench top bearing heater from SKF, worked well
    Now I have my own
    http://www.amazon.co.uk/Andrew-James...duction+cooker
    Actually works better!
    Might be the basis of what you want?
    Mark
    I have one aswell (30 with free delivery off Ebay)...

    They are also very good for pre heating items prior to welding or brazing...so long as you wrap said item in a fire blanket to stop it melting the top fascia.

    Rob

  2. #32
    Join Date
    Mar 2010
    Location
    switzerland
    Posts
    986

    Default

    i always thought it was just a coiled tube conected to some kind of power source. this starts simple, but gets out of hand quickly (i dont think you want to build it yourself):

    http://www.mindchallenger.com/inductionheater/

    the 1200w heater mentioned earlier is nice, but what about something in the 5kw range?

  3. #33
    Join Date
    Oct 2005
    Location
    British Columbia
    Posts
    3,444

    Default

    Wow, look at what the cat drug in after five and half years.

    Judging by the number of views during that time period it looks as though I'm not the only one enamored with the concept of an affordable induction heater for the shop.
    Although I did not acquire one yet the thought of a portable and affordable induction heater still lingers. I've seen a few over the last few years and have been impressed with their capability. Even the 120 volt units are impressive, although with two 50 amp 240 volt circuits in the shop I'd probably lean that way if I take the plunge. But for now my gas fired heater does offer all the bang for the buck that I really need.
    But it's always nice to venture on the road less traveled, call it tool envy for lack of a better term.

    I have seen one of these portable 120 volt units in action and really like the versatility they offer. Although for the type of applications I'm interested in now, a 240 volt version would be a little more capable.
    Although I have seen the above type of unit go for well below what is listed in the link I left. I believe I remember seeing them for about $460 US delivered to my door in Canada, which is good, as prices up here for most things I need are strictly Hollywood.

    I want to thank all of those who contributed the ideas and links to this old beast of a thread as I'll keep researching all avenues. All info here will help both myself and others in pursuit of this concept.

    Thanks guys, your info, knowledge, and links are always much appreciated.
    Home
    Good judgment comes from experience, and experience....well that comes from poor judgment.

  4. #34
    Join Date
    Jun 2002
    Location
    Grand Blanc Michigan
    Posts
    3,503

    Default

    Quote Originally Posted by mayfieldtm View Post
    Take a look at the Roy-1200 (1200 watt) from Fluxeon...

    www.fluxeon.com/web_store

    Kits and parts under $300...

    I have one of these running in an industrial environment for several years now, with no problems.

    It's used to anneal flat Spring wire where a sharp bend is to be made.
    Wire is about 1/16" x 1/4" and heats to red hot in less than two seconds.
    This is done every 5' or so and is repeated several time per minute.

    If I remember, I payed less than $200 for the Kit and another couple hundred for a rugged enclosure and wire guides and such.

    Playing with the Roy-1200, I was surprised that I could melt a good sized bolt in no time at all.

    The trick is to make the heating coil the proper shape for the particular job.

    I know a person that heats "Gitters" in sealed Neon tubes with one of these.

    (no affiliation)

    Tom M.
    I just ordered the ROY 1200 kit through work to see if I can improve a crappy soldering operation here. I may have some questions - and a report.
    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
    ~Practitioner of the Electromechanical Arts~

  5. #35
    Join Date
    Mar 2005
    Location
    Bellevue, WA
    Posts
    10,556

    Default

    I wonder if it is possible to use a plasma cutter inverter to drive the inductor. I've no idea what frequencies are involved or needed.

  6. #36
    Join Date
    Aug 2006
    Location
    Beaverton, OR
    Posts
    6,951

    Default

    Quote Originally Posted by dp View Post
    I wonder if it is possible to use a plasma cutter inverter to drive the inductor. I've no idea what frequencies are involved or needed.
    Not really. They share a similar topography but are different. A RF source for induction heating is more like a radio transmitter than anything, it is a tuned tank circuit.

    Frequency is inversely proportional to heating depth, the higher the freq the closer to the surface the heat is concentrated.

  7. #37
    Join Date
    Mar 2005
    Location
    Bellevue, WA
    Posts
    10,556

    Default

    Quote Originally Posted by macona View Post
    Not really. They share a similar topography but are different. A RF source for induction heating is more like a radio transmitter than anything, it is a tuned tank circuit.

    Frequency is inversely proportional to heating depth, the higher the freq the closer to the surface the heat is concentrated.
    That was pretty much the question - by adding a tank circuit to the PC inverter... But I don't know what the frequency is on a PC. Induction heaters use frequencies up to but not in the low AM broadcast band, but can a tank work usefully at say 150kHz? In stick welding mode the cheap 3-in-1 inverters can push close to 200A. The coupler to a tank is often (always?) a toroid core with a single-turn (copper pipe) secondary that drives the tank. At least in the home-made systems I've seen. That would not be needed with a high-current inverter.

    Getting resonance is just a matter of selecting the right capacitance for the inductor you choose. Simple job for my venerable grid dip oscillator. A problem is that a parallel LC circuit has maximum impedance at resonance which would create too-high a voltage from the inverter. A series LC circuit would require high-current through the capacitors as they are at minimum impedance at resonance. I've smoked more than a few hi-power ship to shore antenna coupler components during multi-band tuning of random length antennas

  8. #38
    Join Date
    Aug 2006
    Location
    Beaverton, OR
    Posts
    6,951

    Default

    I think you could use one as a starting point. But you would have to do a lot of reverse engineering to get the board to work without feedback from the current sensor. But really it is no more than a generic switched mode power supply like in a computer. You probably have about as good of a chance of building one from a big brick mainframe power supply.

    I think it would be just as easy to build one of the existing DIY designs.

    I think a lot of oscillators run in the 40 to 50 khz range to get penetration. I have a 2.5kw, 450KHz RF supply and I looked up the penetration depth and it was really shallow. Might be good for case hardening.

  9. #39
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    16,295

    Default

    Frequency can get down into the 10 kHz area, and affects penetration. So does material. The more conductive the material, the shallower the heating.

    In principle, an SMPS drive circuit is a good start..... but you need a coil, and the impedance looking into the coil is important, but it changes with material present vs not, with type of material, etc.

    A current-mode smps drive circuit, probably "full bridge", might well be the best starting point. A control circuit to detect a load and keep a constant power level might likely be good in order to do consistent work.

    Old-school was either motor-generator, or based on "frequency multipliers". Not necessarily very efficient, but reasonably effective.

    The generator would have a lot of "poles" so the output frequency could be much higher than 50 or 60 Hz. A very old thread by Rick Rowlands at Practical machinist had some pics of such a generator. It was made actually for an induction furnace, but the ideas are so similar that it is applicable.

  10. #40
    Join Date
    Jul 2009
    Location
    Waukesha, WI
    Posts
    466

    Default my Induction heater

    I have an induction heater that is rated at a maximum of 18kw and is used for forging and bending and general heating in my suburban hobby blacksmith shop.

    While the 18kw is a it's maximum rated input, most home shops cannot supply enough power to drive it to it's full capacity. I figure more often than not I am in the 12ks to 14kw input range. I runs on 220 single phase, and can handle input voltages to 250 before faulting out the protection circuitry.

    I can bring a 1" round about 1" long to a yellow forging heat in less than 10 seconds... want a longer section heated, just move it back and forth in the coil as its heating. It's sure nice to walk into the shop and begin heating in the amount of time to power the box up.

    The copper heating coil needs to be water cooled as the peak current through the coil is in the neighborhood of 800 amps.

    My system operates at an output frequency of between 30khz and 100khz. The system uses a Phase Locked Loop to adjust the frequency to match the coil. At this frequency it is not like a surface hardening system that heats the outer .060" of the target stock, but is not a penetrating frequency like 400hz-2000hz that is used for deep heating and melting.

    When heating the 1" stock you can observe the center lagging behind the outer area. It seems to heat about .25" in all at once, then the heat soaks to the center. As long as you keep the power on it is not possible to only heat the outer area. As I said, all this happens in under 10 seconds so you have to watch quickly.

    I tried to use the system to melt metal, and it did, but it was not worth the grief. You need to cover the melt with inert shield gas. I find my propane fired crucible furnace to be much easier to use, with the added benefit of the combustion gases present in the furnace effectively shield the metals from atmospheric oxygen.

    This stuff isn't hard to do, it just takes about $3000 plus a water cooler of your choice. I use something similar to a TIG cooler... just homemade and cheaper. The heater needs about 35psi at 2 GPM or so.

    I have another project in mind annealing some cartridge cases. I recently began converting my 1925 M86 6.5X55 to 6.5X51 LPR. Cheap brass and a rifle that I got with the barrel cut down drove this project.

    Its tough to build a coil this small and still have it fall into the inductance range to allow the unit to self tune, but I just add a extra coil that is large enough to resonate and leaves a small coil in series to heat the small neck or the .308 brass for forming. Also need this to fix some .30 Herrett brass that has a tendency to split as well.

    I should have kept working instead of retiring... it seems that I just can't find the time any more... either that or just to many projects. No matter, I'm still having a good time.

    This thread started about the time I got my induction heater... strange I hadn't seen it before.

    paul
    Corollary to Murphy's Law: Paul's Law
    'You can't fall off the floor.'

    Remember, just because you can doesn't mean you should...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •