Propane forge questions

[Wiredude]

Please forgive the noob questions, and searching the forum is difficult (at best) from the app on my phone, but my home internet is down, so here goes...
I see 2 basic designs in the shape of the forge body itself. Most of what appear to be home-built forges seem to use the tubular, 'grill tank' design, while most of what I see commercially available is more of a box design.
I know the tube designs are lined with kaowool and castable, and I'm guessing the box designs are lined with fire brick.
Is there a significant difference in performance/function between the two designs?
I'm thinking of building a gas forge, because living in a residential neighborhood, the cleaner burn of propane as opposed to coal/charcoal seems less likely to annoy the neighbors.

 

[CMS3900]

Circular forges allow the heat to circulate through the forge better. Any forge with a large amount of castable refractory or hard refractory will take longer to come up to temp and normalize than a forge with insulating blanket and a reflective coating. There are a ton of options building a gas forge. Horizontal or Vertical, Naturally Aspirated or Blown, Ribbon Burners, Insulation, Reflective Coatings.. you have some fun research ahead.

 

[EdCaffreyMS]

If your aim is general blacksmithing, with mild steel, then the "box" designs are fine. When working with carbon/alloy steels (blade steels), the "box" shaped forges are a train wreck waiting to happen. To explain..... with the "box" design, burners have no choice but to come into the forge at obtuse angles, creating hot/cold spots throughout the forge chamber. This often wrecks havoc when attempting to evenly heat something, and can be disastrous you're trying to forge weld. While many will claim they can forge weld "perfectly fine" in the "box" design forges, I've been around far too long, and seen far too many instances of failed welds that could be directly tracked to using a "box" design forge for me to ever recommend them. The reason you see them in commercial format is because they are super simple and cheap to build, so the profit margin is high.

If Bladesmithing is your aim, as far as I'm concerned, there is nothing better then a circular designed forge, with a single, properly sized and placed burner. I use both venturi and blower type burners in my shop.....the venturi burners are used in my "general use" forge, and the blower type burner is used in my dedicated welding forge. The reason I advocate a single burner is that there is far less to go wrong, and it's far easier to "tune" then multiple burner forges.

 

[Wiredude]

Thank you both for the info. Since my intent is more bladesmithing, and I intend to build it myself, seems like circular is the way to go. I'll obviously have to do a bit more research as to size and burners. For the time being, I don't really intend to get into any amount of forge welding. I'd really like to be patient, and get more of the basics down first.
That said, if I go to the effort of building myself something, I would like to avoid building something that will limit progression as well.

 

[CMS3900]

Don't think of it as far as limiting your progression. If I have learned one thing in the last four years or so, it is that blacksmithing, in general, is a iterative process. There are no immediate right answers to everything. Think of it like this, there are two options. Option A is buy a forge and get smithing. Option B is make a forge and get smithing. Option A lets you learn about forges from the design you buy, and if you choose to make one later you have that knowledge. This forge will probably not be the "end all - be all" of forges, but it will teach you a lot. Option B allows you to learn about forges a bit up front, design the one you think is the best, and have the pride that you made something. Don't think for a moment, however, that your "saving money" by making it yourself. You are just performing a cost offset of knowledge of forge design gained vs. cost and time smithing lost. Also, what ever you make, guaranteed after you use it, will have some flaw and you will want to change it.

Regardless of which option you take, I think there are a bunch of good folks on this forum that can point you in the best direction.

 

[Wayne Coe]

Check out the attachments on the Forge Supplies page on my website. Build a Gas Forge tells how I like to build a good, tuff, efficient, long lasting forge. The other attachment, Ribbon Burner is about building the burner I use day to day. I can adjust and control the temperature for forge welding Damascus billets, for general forging or for heat treating.

Let me know if I can help you.