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I Forge Iron

Home build induction heater

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Im interested in the plans! or the kit if i have the money.

I second what Ironsmith said. Plans, Parts or a kit would be great! Can't see a big outlay in the budget in the near future, but plans, parts or a kit could probably be swung by more of us with moderate means.

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I sure hope this young man can come up with a product because the value of having my system now can't be overstated. Something at a price point that more folks could afford would be wonderful. However, I'm not sure that this is planned to be a kit or plans. Daniel's last post mentioned his brother finishing up doing some coding. That means software or firmware to me and how you sell something like this as less than a complete system is difficult for me to imagine. I'm not trying to pour cold water on anyones hopes but having been in the business of designing and manufacturing very complicated equipment I'm not sure it's possible. Product liability, UL, documentation, warranty among other things, a HUGE can of worms. Just my 2 cents!

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The physical parts of the machine are simple, if you had them in front of you with instructions anyone could assemble it, the hard part has been redesigning the controls for this type of thing, that's my brothers area of expertise. The boards used so far have just been made at home at home. Once its set we can send it off and get them professionally made and then its just another part of the kit to attach, like buying a video card for your computer.


Offering it as a "kit" would be a possible way to avoid any liabilities, then maybe offering a fee for "kit assembly" for someone that didn't want to do it.


The last six months for me have included an move and new shop build, the last six months for my brother have included a job switch that required travel and endless conference calls. Its starting to settle now though and we just had a few long conversations about the next steps and getting back on track. I'm still using the prototype model in my shop and its held up surprisingly well for a year or so now, I'm sure Ive put a couple thousand heats through it so far, more than a couple now that I think about it even.


I'm sorry if anyone feels we've drug this out forever, believe me Ive stayed on my brother, because as a blacksmith I want a one just as much as you guys! I cant really change the coils on the prototype, its a pain, so I cant heat more than 1-1/4" round.


We feel that this has the possibility to be somewhat revolutionary in the metal world if done right, if you've used any induction forges before then you know why. Especially since nothing like this is available at a hobbyist price point.


As soon the new one is done I will have videos on here of it.

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I personally would be more interested in a kit than a completed item as this may make it easier to customize to suit local conditions like supply voltage and current available, 

also metric or imperial fittings, horizontal or vertical coil connections.

also a kit may be easier for those of us overseas due to how much you have to send and import duties / customs fees

I would like to know about actual measured current use as some places have limits.


here most people have standard outlets that are 13 amps at 240 volts, bigger things are possible

for industry we have 13a 240v 16a 240v 32a 240v all single phase

and 16a 415v 32a 415v at 3 phase ( there are bigger but these are what is normal )


next time you are doing a video can you put a meter on to measure the current, your last vid here had a bar heated up in about 11 seconds, the text said 120v but the vid said 240v.


some commercial ones seem to have oddly low current needs like a 240v 15kw unit that states 32 amp is needed when physics states it should be 62.5 amps.


I would not want to buy something I cannot use due to power requirements.


might I suggest that the connections for the coil are at 45 degrees, that way it is easy to make a horizontal coil or a vertical one.


yes, sorry to keep bugging you but it did seem to be dragging on a bit, hope things settle down a bit for both of you soon

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Offering it as a "kit" would be a possible way to avoid any liabilities, then maybe offering a fee for "kit assembly" for someone that didn't want to do it.



From what I understand, liability is why you see so many kit or plans planes available compared to commercially built small, private aircraft. Also, of course, they can be built less expensively, or  built as time and money allows--not as one lump sum buy.

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  • 4 weeks later...
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Hey all this is Josh, Daniel's brother. Looks like Dan has done a good job string you all up and teasing you with red hot glowing pictures! My apologies for not chiming in earlier but the forging side is more my brothers thing and I didn't want to impose on the community. Although after having the chance to tinker around in his shop, I definitely see the draw. There is something almost hypnotic about taking a cold hard piece of metal and breathing life into with heat and hammer. 


Anyway I just wanted to let everyone know that the third prototype is almost packaged up in it's new case, so Dan will probably have more forge porn for you soon lol. I'm satisfied with it's performance to the point where, after a bit of field testing this version I can finalize kit plans and supply chain to determine a price point.


I know this has been going on for a while but it's one thing to build a forge with a fixed coil and a single power setting but quite another to make a machine that can work with a large range of coils and vary the power output at such high power levels (0-25 KVA input power). Most if not all examples of DIY induction heating you can find rarely peek above a couple KW of input power, those levels are fine if your working with small materials and heating small areas but won't cut it as a replacement for a flame forge in most cases. The few high power examples out there fail to address other very serious concerns such as mains power isolation (so you don't die), a usable duty cycle, power control (biggie), and a host of other safety and reliability issues.


Power control has been a very important factor in making the next forge do what it needed to do, which is heat larger material without having to make physical adjustments to the inner workings of the machine such as transformer tap adjustments. Basically when heating a large work piece more power is not necessarily required, you just need a lower "gear" when the the part is cold. Similar to a combustion engine, the induction heater's inner workings have a limit or a red line. Once the part does heat up (or the car reaches a higher speed) the gear must be raised to keep it's parts from running wild and throwing a rod, er capacitor. You can achieve this by changing the ratio of a transformer which is how some large industrial units work. However this requires manual intervention or complex moving parts with high power contacts adding to cost and complexity not to mention failure rate. I've gone through multiple iterations of just about ever type of power control and have settled on something that yields quick but smooth control while generating relatively low internal heat.


Everything that generates significant heat is water cooled so the case will be sealed up. I've seen the first prototype get totally covered with that black soot/dust junk. I think filters would just be a hassle and get clogged or not used at all. If the inside does need a bit of air cooling I'll just throw in a small radiator and fan attached to the water supply. The electronics have been greatly simplified as well. I've gone from using an analog PLL circuit to control frequency to an all digital setup, with everything being controlled in software I can do so much more and the possibilities for customization are endless. It also takes up much less space, uses less power, is not affected by temperature and sounds cooler. (digital yeeeah, smart phone and stuff...)


I know the majority of people interested in building one of these will probably have more interest in the use of the machine rather than how it works, but I hope that some do dive into the theory. It's really quite elegant the way a handful of natural laws come together and make this phenomenon possible. That being said since my brother is showing all the red hot pics I'll show the nerdy ones.

This is a screen shot of the live data capture coming from the induction heater, this was key in developing the algorithms and control processes, your mind is able to pieces things together when they are presented in the right format (usually visual for me). I am able to instantly see the results of a given formula or routine and discover other associations that made much of this possible.


There is no indicated time base shown but every 7 horizontal squares works out to about 1 second in this case. Walking through the image using the color key for reference, the forge starts out at 10% power (white) while it ramps down from it's maximum frequency (yellow) until it reaches it's resonant frequency. While this is happening the program is reading the phase angle and automatically calculating the set point to determine the resonance frequency. Phase error also come into play here as it must be below a certain level and also affects the rate of change in error correction. Once lock is achieved, the low power hold is released an the inverter current (violet) is allowed to ramp up to the maximum set inverter current (dark yellow). After running a couple seconds you can see that I increased the maximum inverter current twice then decreased it. During this the resonant frequency does not change, the inverter current hugs the set point tightly however the mains current draw (red) does not. You can see this effect more so in the next two events. In the last two events on the chart I am removing the work pice (4" x 1.5" sq bar) from the coil while the unit is running. In the first event I slowly and smoothly remove the work coil, the inverter current remains stable but the input power level (mains current) is lowered. You can also see that the resonant frequency lowered and things get a bit noisy on the phase angle due to the unloaded work coil. In the second event I yanked the work piece out and put it back quickly after the power stabilized. There is a fault routine set up (1 of about 10 so far) to halt the unit if that peak is too high relative to the present power level (one more vertical square and it would have triggered at this level). Back to the mains power dip (red), you can see that when the work pieces is removed from the coil, very little input power is needed to maintain the same output power, this is where the "gear" is raised all the way up to over drive in this case, since we are just coasting downhill with no load. Once the work piece is reinserted into the coil it's all up hill and we need to lower the gear again, very similar to a Continuously Variable Transmission in operation. 



1. When I say "it ramps down from it's maximum frequency (yellow)" but you see the ramp going up, that's because the yellow line is a representation of the time delay creating the frequency, so as time increases frequency decreases.



Full Size Image Link


I also want to say that I'm not reinventing the wheel here, but at times the wheel can be over priced, over rated and behind on technology. Many over seas units toy with the numbers (input vs output power etc) to make it sound like your getting more than you are paying for when in-fact your getting less, like the old RadioShack 1000 Watt amplifier (4 channels x 10 x RMS x BS Marketing). That being said I'm not knocking them all, there are some great units out there at decent prices. And support goes a long way, an ounce of support is worth a lot of $ imo. As Dan stated I do plan on making this an open source community project and offering a kit since many of the parts must be bought in bulk to make pricing feasible. I may also offer an ARU kit (almost ready to use), with things like the control board stuffed and read to go so that the only requirements are mechanical assembly (i.e. limited to no electronics work). 


I hope you are all enjoying your work and your hobbies, hopefully mine can improve your experience and create new ones in the near future.



Edited by ReactorForge
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Thank you, Induction Brothers. As with workshops to build Rob Gunter's recuperative forge and Clay Spencer's treadle hammer, I foresee regional groups to purchase items in quantity and to fabricate your induction forge at a joint workshop. I shall likely host a workshop in the Washington, DC area.

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