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PStechPaul
02-19-2016, 02:15 AM
I have a one pound jar of Cherry Red compound that I have not yet tried to use. I also just found this induction heater for $8.55 that runs on 12 VDC and it looks like it might work well for small parts like screwdrivers, taps, and single point gear cutters.

http://www.midwayusa.com/Product/119479/cherry-red-surface-hardening-compound-1-lb

http://www.banggood.com/5V-12V-ZVS-Induction-Heating-Power-Supply-Module-With-Coil-p-1015637.html

http://img.banggood.com/customers_images/large/2016012914065194-1015637.jpg

http://img.banggood.com/customers_images/large/2016021717165624-1015637.jpg

http://img.banggood.com/customers_images/large/2016010417245870-1015637.jpg

http://img.banggood.com/customers_images/large/2016010422145813-1015637.jpg

It looks like it should work OK, and for the price there is little risk.

The process seems simple enough, but I wonder if the induction heater would work as well, and possibly provide some advantages. I also wonder how it might work on high carbon and alloy steel like 4140?


https://www.youtube.com/watch?v=9tlsq2ESQz0

hojpoj
02-19-2016, 07:12 AM
I'll be watching this closely since that exact unit is in my banggood wishlist.

Carld
02-19-2016, 08:12 AM
Is that the same as Kasenit? I like the induction heater idea. I went to banggood site and man, they have some interesting stuff. I bookmarked the site. How big is the hole through the coil? How long did it take to heat up the screw driver?

10KPete
02-19-2016, 08:40 AM
Hardening compounds don't care what the heat source is. They just provide the free carbon to enrich the steel.
The steel doesn't care either. Get the temp above critical, all the way through, then quench appropriately.
Alloys like 4130 don't need the extra carbon. Hardening compounds are intended for low carbon steels.

I like induction heating 'cause it's clean, fast and cheap even for larger parts.

Pete

jihe
02-19-2016, 09:21 AM
Interesting, I've ordered one! I wonder if it would be possible to put a lid over it and have a flow of co2 or argon and not having to deal with scaling?

J Tiers
02-19-2016, 09:23 AM
The induction heater may allow more opportunity for decarb problems, since it lets air be around the part to potentially eat the carbon. With fire heating you can often position the part in a reducing area of the flame so surface carbon is not sucked out of the part.

But the induction heater may let you provide an inert atmosphere more easily.

I am surprised that little heater unit has enough power at 12V. Probably the part size is rather limited, due to the coil. With regular induction heaters you can usually suit the coil size and shape to the work, because the frequency is established elsewhere. That one may use the coil as part of the "tank circuit", so that it is not as adaptable.

hojpoj
02-19-2016, 09:47 AM
Interesting, I've ordered one! I wonder if it would be possible to put a lid over it and have a flow of co2 or argon and not having to deal with scaling?

Keep in mind that depending on which part of the site you go to, it may be coming direct from china, so it may arrive for 3-4 weeks. That being said, they do have some warehouses in the US and EU with a more limited offering from the direct-from-china site, and from personal experience it only took 1.5-2 weeks for the stuff to get to me.

dx.com is all direct-from-china, but has as good an offering as banggood.com, I check the new arrivals frequently to see what weird stuff shows up.

10KPete
02-19-2016, 10:03 AM
Interesting, I've ordered one! I wonder if it would be possible to put a lid over it and have a flow of co2 or argon and not having to deal with scaling?



Absolutely! That's how it's done commercially, with the coil inside a purged container.

Pete

loose nut
02-19-2016, 10:10 AM
I wonder how long an $8 unit will last.

Jaakko Fagerlund
02-19-2016, 10:40 AM
I wonder how long an $8 unit will last.
Looking at the parts there's nothing special and the parts of course will cost way less than 8,55 USD in production quantities. So I don't see any reason why it wouldn't last.

Seastar
02-19-2016, 10:53 AM
Paul
That's an interesting device. I think I'll buy one to play with.
I noticed two meters in your pictures.
What were they reading?
Bill

Willy
02-19-2016, 12:42 PM
Paul
That's an interesting device. I think I'll buy one to play with.
I noticed two meters in your pictures.
What were they reading?
Bill

Yes good questions. Looks like you are using a small 12v 5ah motorcycle battery. If so is this capable of supplying adequate voltage and amperage?

I've been looking for for something like this for quite some time, actually about 3 times this size would be better. I actually ordered one from Ebay about a week ago @ $5.99 US/free shipping.

Looking forward to your write-up Paul as I'm sure it will be another 3 weeks before I see anything here.

boslab
02-19-2016, 01:36 PM
There are loads of ceased bolt heaters out there that look lie they may be based on this, the average price for a wand is about 1000!, also bearing heaters that also cost a fortune
Mark
https://www.google.co.uk/search?q=seized+bolt+heater&rlz=1C9BKJA_enGB605GB605&hl=en-GB&prmd=svin&source=lnms&tbm=shop&sa=X&ved=0ahUKEwiLgNGrvITLAhWC0hoKHcAWC9QQ_AUIBygB&biw=1024&bih=653

Forestgnome
02-19-2016, 03:31 PM
Just ordered mine. I'll be looking into how to regulate it to get the right temp, maybe input voltage/current regulation.

DICKEYBIRD
02-19-2016, 04:10 PM
I'm holding out for the Mark II model that's twice as big for $17.10.:cool:

rkepler
02-19-2016, 04:24 PM
I ordered one, too. Added a 20A 12V power supply. All for $22. The world is weird... but fun.

PStechPaul
02-19-2016, 04:58 PM
I have not ordered one yet, but I will. The pictures are from customer reviews on the Banggood site. There are also some Q&As that give the coil ID as 19mm, and they are going to offer a 1000 watt unit "soon". I have bought quite a few things from them, and I have been pleased with most. They are very responsive to questions and complaints, and I got a partial refund for the LED bulbs that burned out in a few months. Some other products I bought and recommend:

http://www.banggood.com/SKMEI-1049-Solar-Power-Dual-Time-Waterproof-LED-Analog-Digital-Watch-p-967944.html (Still working and looks good after over a year)

http://www.banggood.com/High-Temperature-Polyimide-Film-Heat-Resistant-Tape-5-Size-p-954755.html

http://www.banggood.com/Eachine-H8C-Mini-With-2MP-Camera-2_4G-6-Axis-Headless-Mode-RC-Quadcopter-RTF-p-1008944.html (Still need to learn how to fly it)

http://www.banggood.com/Wholesale-Mini-3-in-1-0_5mW-Red-Laser-Pointer-White-LED-Flashlight-With-Keychain-Clip-p-43059.html (Well made, looks good, only about $1.50)

http://www.banggood.com/Night-Safety-Dog-Collar-Waterproof-LED-Pet-Flashing-Collar-p-80287.html

http://www.banggood.com/1_5X-2_0X-2_5X-3_5X-Headband-Magnifier-Magnifying-Glass-Loupe-With-4-Lens-p-984654.html (Optical glass lenses, well made)

http://www.banggood.com/Wholesale-Multipurpose-Laser-Level-Aligner-3-Bubbles-Measuring-Tape-Ruler-p-27788.html (Seems great for the price)

http://www.banggood.com/50cm100cm150cm200cm-LED-5050-Waterproof-IP65-RGB-USB-LED-Strip-Light-DC-5V-p-1000891.html (Cool effects -used for Christmas lights - USB 5V powered with controller)

http://www.banggood.com/Creative-Log-Wood-Shape-Pillow-Home-Office-Car-Comfortable-Cushion-p-953611.html (Amazingly soft)

http://www.banggood.com/Aluminum-MiniAture-Small-Clamp-On-Table-Bench-Vise-Tool-p-944663.html (Cheaply made but useful)

http://www.banggood.com/Professional-Vises-Bench-Swivel-Vise-With-Clamp-3-inch-Tabletop-Vise-p-933490.html (Good for the price)

rolland
02-19-2016, 08:18 PM
Thanks for posting that, I have to make small cutters from time to time and this is just what I need for hardening. Hope it works out .

Dan Dubeau
02-19-2016, 08:50 PM
I bought one too, as well as a couple other things. Never heard of that site before, but after some poking around it seems legit. Mine was around 11.50cdn with free shipping.

Will a switching computer supply work for this? Hoping so, as I've got a few lying around. Can't wait to try it out

J Tiers
02-20-2016, 12:03 AM
My advice is not to get too excited just yet.

The thing has too little power to do much real work, I'd doubt it could heat a seized nut of any size, too much heat loss to everything else. Probably about 50 to 100 W would be as much as that unit could do, and it may be less than that. I'm thinking the little MosFets are probably good for about 10A max with no cooling, there are lots of low milliohm level on-resistance units around.

Accounting for heating and the on-resistance rising, a one milliohm on-resistance unit would probably get to about a quarter watt dissipation at 10A, and that's about as far as it is likely safe to take a little SMT plastic case mosfet. of course, they may not have any current limiting, and they may be pushing the parts to max.

There are two devices, so if they are push-pull, it could do a bit better. If it is set up as a half-bridge, then it would not be too sensitive to resonance, and that would be more adaptable without needing any fancy controls. in fact they would likely be careful NOT to have resonance so the voltages would stay under control, although the resonant converter will have less losses at higher voltages (not a problem here, since the 12V is so low). Can't see what's underneath the capacitors, and I have not looked for induction heater control ICs....I'd bet there are a number of them.

Actual induction heaters useful for bigger items have bigger coils, and quite often they are water cooled.

No free lunches......

If you want to easily heat items around the size of the screwdriver tips in the pics, well then go right on, because it seems to do those quite nicely.

If you can hold them with something that won't suck up heating power, you could hold the item in the coil right over the quench water. Get it suitably hot, and drop it in. Done.

With some adjustments of input voltage, it might be possible to use it to draw the temper also. That would take the ability to control power reasonably closely, and ideally with feedback. But you could also just watch the colors.

Maybe this needs some development...... That being what I do.......

J Tiers
02-20-2016, 01:57 AM
here's a very simple circuit that accounts for most of the visible components in the $8 unit... (but the $8 unit does not need a center tap, so it is more complex.)

It will self-oscillate and so adapt to loads and changes in resonance as long as the draw is not so great as to kill the oscillation.

http://www.rmcybernetics.com/projects/DIY_Devices/diy-induction-heater.htm


And here is one a bit closer to the probable $8 version. This has two coils, just like the unit in question. And the general number of parts is about right. We'll call it a match.

https://markobakula.wordpress.com/power-electronics/500w-royer-induction-heater/

While it won't compete with the price, it does give some possibility for expansion and increased power.

bob ward
02-21-2016, 10:39 AM
I use Cherry Red frequently to harden cutting tools, punches, drifts etc, but so far only by the traditional flame heating method. The induction heater idea looks like a good'un.

51cub
02-21-2016, 11:30 AM
Thanks for showing us! Like all the forums I'm in, every day I find out about something new I have to try, and something else I have to build. All of my hobbies and interests are becoming a gateway drug to spending more money, and using up even more room in the garage

_Paul_
02-21-2016, 11:32 AM
Looks like it might take a small trigger or sear .... at 6.04 I think I will treat myself.

Paul

SirLesPatterson
02-22-2016, 04:42 PM
Mine arrived today. Right off the bat I accidentally fed it 24vdc for about 10 seconds. It worked GOOD! I don't know if I damaged it or not but I guess it's an affordable enough lesson if I did. I corrected things and it still seems to work good at 12vdc.

danlb
03-01-2016, 11:54 PM
I got one just for fun.

I've seen some induction coils that are tightly wound, and others that have a gap between each coil. Which way should they be on this model, tight or loose?

My bench supply will only put out 3 amps max, so I have my heater running off a power supply from a 20 year old 486 PC. It's unbalanced, so only putting out 10.7 volts on the 12 volt buss. It drops to 9.4 volts under load. It was able to get a 1/4 inch steel rod orange-red in a short amount of time. Judging by the slate gray color that it turned, it was stainless. :)

Strangely, some stainless zip ties did not heat at all.

How many amps is it supposed to pull?

Dan

_Paul_
03-04-2016, 11:52 AM
My unit arrived a couple of days ago, connected it to a heavy duty 12v car battery it works well for it's size, the largest component heated so far has been around 10mm in dia.

Initially it didn't seem to get the components really hot (only dull red) but reading through the item comments from Bang-good they say it's best to solder the coil direct to the board did that and it now heats all my sample pieces to orange.

I see Bang-good have now added a 1000W unit (http://www.banggood.com/Low-ZVS-12-48V-20A-1000W-High-Frequency-Induction-Heating-Machine-Module-p-1038472.html) to their catalogue in the last few days, looks a fair bit of kit will probably order one :)

Paul

achtanelion
03-04-2016, 03:23 PM
If you go to aliexpress, you can get the 1KW (http://www.aliexpress.com/item/1000W-ZVS-Low-voltage-induction-heating-board-module-Tesla-coil/2012310211.html?ws_ab_test=searchweb201556_6,searc hweb201644_5_505_506_503_504_10020_502_10001_10002 _10017_10005_10006_10021_10003_10004_10022_10018_1 0019,searchweb201560_9,searchweb1451318400_-1,searchweb1451318411_-1&btsid=b5d92ef3-8b81-43b7-b314-3ffdb1705fbb) unit for less than half that price

PStechPaul
03-04-2016, 04:04 PM
The Banggood price is $35.49, while the one from AlieExpess is $37.99.

http://thumbs.ebaystatic.com/images/g/bc4AAOSw%7EOVWzUaG/s-l225.jpg
You can get from Hong Kong via eBay for $33.43:
http://www.ebay.com/itm/1Pcs-1000W-ZVS-Low-Voltage-Induction-Heating-Board-Module-Flyback-Driver-Heater-/231856758361

J Tiers
03-04-2016, 04:13 PM
The 1000W is the pulse time better used and not to used the high current mode continuous for high voltage.

Do not neglect for the coldness to employ on coil and recommended for the fan to use from top.

achtanelion
03-04-2016, 05:02 PM
Mea Culpa, I hadn't noticed that the banggood link was showing me a price in Brazilian reals for some reason.

Daminer
03-04-2016, 06:42 PM
The 1000W is the pulse time better used and not to used the high current mode continuous for high voltage.

Do not neglect for the coldness to employ on coil and recommended for the fan to use from top.

Wattsamatta JT, is the ChingLish putting a hitch-in-yer-gittalong of understanding their fine instructions? [:-)

J Tiers
03-04-2016, 08:16 PM
Wattsamatta JT, is the ChingLish putting a hitch-in-yer-gittalong of understanding their fine instructions? [:-)

Direct quote:

"Although this circuit can tolerate 20-30A input current moment, but do not exceed 15A when safe work, you can easily add an ammeter between the power supply and heating driver board but always monitor the current overload.

This circuit can not only do the induction heating, the copper tube into the high-frequency transformer, is a powerful inverter.

1, To increase the heat sink using a customized substrate as thick as 8.5mm!
Cooling capacity is very powerful.
2, Using the M4 pillars, fever smaller, more efficient."

I think if above is not followed, then it will "bang good". D'you suppose they started by selling fireworks?

danlb
03-04-2016, 10:51 PM
There is also verbiage on the banggood page for the 100 watt unit that cautions against low voltage conditions. It suggests that you turn on a switching power supply and let the voltage stabilize before powering up the heater.

Despite all that, I feel compelled to buy one. The wife won't let me have a blast furnace in the back yard.

Dan

J Tiers
03-05-2016, 12:43 AM
The AlieExpress verbage is pretty good too....

Quote:

"7. The higher voltage, the higher current when heating the same things, the effect is better, but at the same time heating is also higher, therefore the choice of input voltage is based on your need. Such as heating under 1cm square small objects, use the 24 v voltage.

8. buyer need self-provided power and water cooling device

9. When made with switch power supply, because of the high power generally has function of soft start, namely just powered on the output voltage is slowly rising, while if before the voltage up to 12v connected induction heating circuit, will not work and burn MOS tube. So voltage reaches more than 12 v connected induction heating circuit.

10. The volume of heated objects cannot be more than 1/10 of the heating coil internal volume (that is, the heating cylinder diameter more than 1/3 heating coil diameter), otherwise it may because of overload and burned circuit or the power supply. Although this circuit can tolerate 30A input current, but the insurance for the purpose of work not more than 20A."

I think I understand that, which scares me....

No, I could not do better in chinese..... but I know how to hire a translator!

danlb
03-11-2016, 11:53 PM
I bought the smaller 12 volt, 7 amp unit the day this thread started. The PC power supply 12 volt rail was dropping to 9 volts or so. I ordered the same 12 volt, 12 amp power supply from banggoods after seeing RKEPLER's post (post #16). Yuck. Came from China. Oh well. I waited patiently (since I forgot it was coming) and it came a few days ago.

Today I put it all together. The 12 volt supply powers it up nicely. There is no drop in voltage as I inserted various things into the induction coil.


Now for the test. I had made a D-bit of A1 rod to ream a .22 barrel (made from 4140 steel) as an experiment. It never did get as hard as I wanted it. A file could cut into it even after I followed the right procedure for hardening it. I made it my test piece.

First, I tried the file test again. The edge of the file bit into the steel easily, leaving a groove. I used the induction heater to bring the .217 ground rod to a nice deep red (15 seconds???) and stirred it in the Cherry Red. It sizzled like water, and built a nice coating. I reheated it, and much of the coating melted off the rod. As soon as it reached a nice red I dunked it into a pail of cold water. The coating dissolved as I swirled it.

Time for the file test. The file skidded off the surface. :)

Summary; You can use the induction heater to heat 1/4 inch mild steel rods to the temperatures needed for case hardening with Cherry Red. It was fast and easy, with no visible scale. I hope to be able to use it for doing a little forging of pen knife blades as well as making small tools. That would be cool.. er.. Hot. :)

Dan

rkepler
03-13-2016, 01:36 PM
Summary; You can use the induction heater to heat 1/4 inch mild steel rods to the temperatures needed for case hardening with Cherry Red. It was fast and easy, with no visible scale. I hope to be able to use it for doing a little forging of pen knife blades as well as making small tools. That would be cool.. er.. Hot. :)

Dan

A quick test when hardening is that the steel is at or above the critical temperature when it no longer sticks to a magnet. For real small stuff it's good to take it above critical as it'll start cooling as soon as the heat source is taken away - I used to quench directly from the furnace by add some sacrificial bits for mass in the bag and simply cutting the bag over the quench. (Later I got lazy and just used A2 - that stuff sneers at you and hardens when you look askance at it. Can't not harden it until it's in pretty big sections.)

PStechPaul
03-13-2016, 05:27 PM
I haven't bought one yet and I might spring for the higher power unit. But as for using two coils to get the length needed for a knife blade, it might be possible to make a single coil with more turns, but flattened so as to better fit the profile of the blade. The inductance per turn is proportional to the enclosed area, so a long flat coil with more turns can have the same inductance as a shorter round coil.

Dan Dubeau
04-04-2016, 10:13 PM
Mine was waiting in the mailbox tonight (finally, ordered it 2/19). Put the kids to bed, and hooked it up to a small motorcycle battery (ytx9-bs) and a 6amp battery charger. Grabbed a chunk of tig rod, and it brought it up to cherry red fairly quickly. Grabbed a 1/4" chunk of 01 and shoved it in the coil. Could feel it heating up but, the clicking and popping from the battery made me shut it down (didn't want to wreck the battery). I know it's a small one, and very limited in what it can actually do, but I'm looking forward to playing with it a bit more with a proper power supply.

Just playing around for 5 minutes I can tell how useful a larger one would be for the work I do.

Black_Moons
04-04-2016, 10:33 PM
I bought the smaller 12 volt, 7 amp unit the day this thread started. The PC power supply 12 volt rail was dropping to 9 volts or so.

Dan

Buy a 6V light, highest wattage you can find (a 25~50W headlight would be nice), and hook it up to the 5v rail of the PC power supply and your 12v rail won't drop to 9v under load.

J Tiers
04-05-2016, 12:12 AM
hah.... I have used the one I have sitting on the bench in "ultra-kludge" construction, several times now. At various stages of modification. It's giving me ideas of what it needs to be capable of.

A 12V 7 A unit is gonna be way to small in very short order, unless you are a watchmaker.... That I can tell you now.

Rustybolt
04-05-2016, 08:42 AM
"Strangely, some stainless zip ties did not heat at all. "

Non ferrite stainless takes a lot more energy to heat up. The coil is heating the iron in the steel.

Dan Dubeau
04-05-2016, 09:33 AM
hah.... I have used the one I have sitting on the bench in "ultra-kludge" construction, several times now. At various stages of modification. It's giving me ideas of what it needs to be capable of.

A 12V 7 A unit is gonna be way to small in very short order, unless you are a watchmaker.... That I can tell you now.

I knew this one would be too small to be really useful for me, but for the price I thought It'd be fun to play around and wet my appetite. I have no idea what the power requirements would be (I'm an electrical neophyte), but if I had one that could bring 3/16"-3/4" O1 up to 1500* I would be a happy man.

J Tiers
04-05-2016, 11:02 AM
I knew this one would be too small to be really useful for me, but for the price I thought It'd be fun to play around and wet my appetite. I have no idea what the power requirements would be (I'm an electrical neophyte), but if I had one that could bring 3/16"-3/4" O1 up to 1500* I would be a happy man.

For the high end of that you are going to want a couple kilowatts, anyway, 5 or 10 if you want it to happen fast.

Sparky_NY
05-06-2017, 10:30 PM
I just ordered two of the 1kw flavor heaters. $22 for two on ebay.

This thread is a month old and I am wondering if anyone got their units since and have any results to report. I hope to use it to harden some tiny parts for a gatling gun I have in progress, like the firing pins and hammers which are just 5/16 pins basically. I am using O1 steel.

RichR
05-06-2017, 11:31 PM
I just ordered two of the 1kw flavor heaters. $22 for two on ebay.

This thread is a month old and I am wondering if anyone got their units since and have any results to report. I hope to use it to harden some tiny parts for a gatling gun I have in progress, like the firing pins and hammers which are just 5/16 pins basically. I am using O1 steel.

News flash, the last post was April of 2016 which is 13 months ago.:rolleyes:

Glug
05-07-2017, 09:00 AM
This thread is a month old and I am wondering if anyone got their units since and have any results to report. I hope to use it to harden some tiny parts for a gatling gun I have in progress, like the firing pins and hammers

Induction heaters? Gattling guns? Firing pins? Holy Rip Van Winkle Bat Man.

The world has moved on, to these little spinning toys that have a 3:1 ratio of useless bearings. It's probably a good time to nap for a year, the next fad has to be better.

Sparky_NY
05-07-2017, 10:59 AM
News flash, the last post was April of 2016 which is 13 months ago.:rolleyes:

Ha! I ignored the year it looks like! Oh well, even better, the guys that ordered one have had some time to play now. There should be more user reports out there.

I have since seen that they even have a 2500 watt version now. The coil type has limited uses but I imagine a different coil could be used just like the others.
(http://www.ebay.com/itm/220V-2500W-Induction-Heater-Tesla-coil-for-Quenching-Annealing-Heat-Treatment-/322022941871)

J Tiers
05-07-2017, 11:05 AM
Ha! I ignored the year it looks like! Oh well, even better, the guys that ordered one have had some time to play now. There should be more user reports out there.

I have since seen that they even have a 2500 watt version now. The coil type has limited uses but I imagine a different coil could be used just like the others.
(http://www.ebay.com/itm/220V-2500W-Induction-Heater-Tesla-coil-for-Quenching-Annealing-Heat-Treatment-/322022941871)

That one is actually for a cooktop, not metalworkig, and the coil for it is probably not easily adapted for smaller items. But with some work, it possibly could be adapted.

danlb
05-07-2017, 11:25 AM
Ha! I ignored the year it looks like! Oh well, even better, the guys that ordered one have had some time to play now. There should be more user reports out there.


No problem with reviving a thread with on topic questions.

I have not used mine since the original tests. I picked it up for heat treating, but have not had much use for it yet.

Dan

hornluv
05-07-2017, 12:26 PM
Weird. This is the fourth reference to banggood.com that I've seen today and I had never heard of the site. If I had, I would never have imagined it was a retail site, if you know what I mean. They've got some pretty neat stuff.

michigan doug
05-07-2017, 05:23 PM
Weird. This is the fourth reference to banggood.com that I've seen today and I had never heard of the site. If I had, I would never have imagined it was a retail site, if you know what I mean. They've got some pretty neat stuff.

There's a term for that.

The Baader-Meinhof Phenomenon

https://psmag.com/there-s-a-name-for-that-the-baader-meinhof-phenomenon-e5bf3ea87cd2

flylo
05-07-2017, 06:05 PM
I have a couple dental furnaces 120V goes up to 2000 degrees pretty fast & uses vacuum to seal the door. Set the temp you want & it holds it well. Had 3 but gave a friend one.

Sparky_NY
05-07-2017, 06:37 PM
I have a couple dental furnaces 120V goes up to 2000 degrees pretty fast & uses vacuum to seal the door. Set the temp you want & it holds it well. Had 3 but gave a friend one.

That sounds great for hobby heat treating ! Being sealed you could probably inject inert gas with a bit of modifying.