Gas Forge

Any opinions on a Devils Forge? I am looking at the DSFW double burner unit that is longer than the other.

Are you intending to forge blades or just heat treat them?

Maybe both at some point, but for now just HT.

Thom, if you're heat treating anything other than 1084 or 1070, I HIGHLY recommend that you invest in a Paragon or an Evenheat kiln with digital controller. I picked mine up for a song on Craigslist. Lots of folks on YouTube and all over the web will swear that their down and dirty heat treat with a bbq grill, magnet and used motor oil is just honky dory....it AIN'T. Plenty of pros send blades out for heat treating (by guys who do nothing else) for a reason....it's easy to get wrong.
-Mark

I'm playing devils advocate here. Don't buy any damn product which is made for any specific purpose. Use the old brain and put together something based on your own needs.

Contrary to popular belief you don't need to buy stuff to do what you want...you can in fact make it yourself. The knowledge applied to making your own forge is awesome. Build what you want to do and don't overly complicate the wheel.

Stuff that you make is more rewarding than paying a premium for a pre-made product.

CutFingers said:

I'm playing devils advocate here. Don't buy any damn product which is made for any specific purpose. Use the old brain and put together something based on your own needs.

Contrary to popular belief you don't need to buy stuff to do what you want...you can in fact make it yourself. The knowledge applied to making your own forge is awesome. Build what you want to do and don't overly complicate the wheel.

Stuff that you make is more rewarding than paying a premium for a pre-made product.

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I agree with your philosophy whole-heartedly. Working with this orientation can help to develop a wide variety of surprisingly useful skills. However, this doesn't necessarily apply here unless Thom is, as Mark mentioned, working in the most simple carbon steels or is willing willing to develop a tricky finesse through a long process of trial and error by dialing in ramp/soak temps and making critical analyses of the resulting blades. What Thom hasn't mentioned in this thread is that he's, so far, used O1 and is looking for a modern stainless steel. O1 has a working tolerance of less than 50 degrees at soak temp. Hitting 1450 is doable even just with a torch, and certainly with a gas forge, but uniformly holding the length of the blade between 1450 and 1500 degrees for the minimum soak time of ~15 minutes will prove to be extremely challenging. You absolutely can harden O1 with a torch or forge, but outside of the conditions given by a kiln, etc. the blade is unlikely to exhibit the treatment qualities that we expect in a good knife. This is why I had previously suggested to Thom that he send his blades, at least initially, out for professional heat treatment.

It's definitely possible to make your own electric heat treating oven. If you're forging, you can certainly make your own forge.

tl;dr Simple carbon steels can take a simple heat treat. O1, and beyond, takes something else.

You can make a perfectly good gas HT furnace without too much difficulty. You can also do HT in a regular forging furnace, but it is a little tricky.
Concerning O1, with sufficient knowledge and care you can successfully HT it in a gas forge. Destructive testing is really the only way to get your process right, rather than going by what you read on the internet. I have found even stockholder's (thus presumably manufacturer's?) HT spec to be off on occasion. Without the specific assay for the batch you have and a resident PhD in metallurgy, I'd take HT specs (and people's opinion of them) more as guidelines, with your own destructive testing experiments pointing you in the direction of getting what you want with the set up you have.

Dan P. said:

You can make a perfectly good gas HT furnace without too much difficulty. You can also do HT in a regular forging furnace, but it is a little tricky.
Concerning O1, with sufficient knowledge and care you can successfully HT it in a gas forge. Destructive testing is really the only way to get your process right, rather than going by what you read on the internet. I have found even stockholder's (thus presumably manufacturer's?) HT spec to be off on occasion. Without the specific assay for the batch you have and a resident PhD in metallurgy, I'd take HT specs (and people's opinion of them) more as guidelines, with your own destructive testing experiments pointing you in the direction of getting what you want with the set up you have.

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I agree on the testing and that you should take heat treatment spec sheets as guidelines. Tempering charts in particular are often off, and way off if you do something like a liquid nitrogen treatment.

Thom, I would suggest you avoid heat treating O1 in a forge unless you have a hardness tester (so you can get an idea of what's working and what's not) and even so I will suggest to you that you could get better results in other ways. O1 is easy to get "hard", but it is not at all a steel that is easy to get to its true potential without heat control and has a tendency to partially air harden when normalized and/or crack if quenched improperly. 1084 or 1080 can make an excellent knife and they should not be looked down on like they sometimes are. Additionally I have repeatedly been able to get better results heat treating them by eye in a forge than to a kiln, much to my surprise (blind side by side tests by us and by outside pro kitchen testers). Kilns are not the even-heating wonder tools that people say they are either, but at least they have the ability to hold a rough temp for a period of time.

If you do build or buy a forge for heat treatment ideally it would need to be designed for that purpose. The forge you mentioned is not built for heat treating and is really more of a forging forge designed for blacksmithing. You could retrofit a baffle into perhaps, but for the cost you will not have a plug and play system that can provide you with the best results. You may be better off building one that better fits your needs. It is not particularly difficult or expensive. You will not need a forge that can get to forge welding temps like the one you are looking at and you really want control-ability at lower temps and good evenness.

Additionally, if you get an electric kiln, I suggest the Evenheat, though we have not used one (we have a Sugar Creek which has since gone out of business, but it is a very similar build to the Evenheat). We have fits with our Paragon and uneven/overheating due to radiant heat transfer and its design. We only use it for shorter knives and only if they are foil wrapped, which are very few indeed. For kitchen knife lengths it will overheat the knife tips very badly, making the most fragile part of the knife brittle. The small interior space, the locations of the coils, and the location of the thermocouple near the door really don't give you the precision and heat evenness that is ideal or I would even say necessary.

Salts of course are the best since they have evenness, avoid decarb, etc. but making molten lava a part of your everyday life is not a light decision.

Best of luck and if I can be of help for specific questions feel free to send me a PM or email.

~Luke

Thank you for all of that info.

I see a couple of references here to O1 and its heat-treatment that I'd like to comment on;
First; It's not the source of heat, gas vs. electric, that is important, it is the quality, i.e. stable, uniform and suitable for the task at hand.
Second; The idea that you need a PhD in rocket surgery to successfully HT O1 is not true. If a competent person HTs O1 and 1080 to a good, conscientious standard, but using low-tec, whether it is "optimal" or "unlocking the true potential" of the O1 or not, the O1 will likely out perform the 1080, because even if the critical temperature is held only a limited time, there will still be enough alloying elements in solution to improve the performance of the steel.
I'm not trying to be quarrelsome, just speaking from my own, first hand experience of metalwork (not from something I read on a website).

I respectfully have to say that I'm much happier with my 1084 blades heat treated in my Evenheat than with the O1 I've heat treated in my forge. Your mileage may vary.
-Mark