Is round realy better

JTknives

JTknives

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Jun 11, 2006
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i have been thinging about this more lateley. is a round chamber forge realy better or is it hype. yes the flame will swrial around the chamber but once somthing enters the chamber would it not inerrupet the flow. i have been thinking of getting the knifemaker forge from www.diamondbackironworks.com

thay talk about the hype of round chambers. this forge is very easy to matane. has anyone tested a round chamber or square with smoke and air to see what happens like in a wind tunnel.
 
my forges i make are square and i've also made a round one but for casting(vertical) it got hot, but my little 8''x16'' box w/homemade burnner 'll reach weld temp right now and stay consistant enough temp for welding w/no prob. it was actually built from plans on a site by bob warrner. i did start a horizontal pipe forge but my square one works so well i never finished the round thats just my 2 cents.
 
That was a very interesting link to Diamondback ironworks. I don't know the answer to your questions but it has got me thinking. There is the saved time in maintenance as well as the very reasonable price that these fellas are selling their forges for. That is a positive. Ellis's forges do have ports to install a thermocouple for precise measurement of temp. That is a plus that the fellas at Diamondback do not note. As far as the air flow, that is the work for an investigative engineer/scientist. If the forge accomplishes the job that is all that matters to me. I say buy it, test it and if it works well let the rest of us know.
 
Properly built, a round forge does just as well as any other, with a few advantages for knifemaking:

The "swirl" effect you're talking about isn't at all interupted in a horizontal body forge (see Cashen's website for basic design info), but it is in a vertical body forge (see Fogg's site for this one). Of the two I personally prefer the horizontal, for a few reasons:

As stated, the "swirl" or "vortex" effect isn't interrupted, as your workpeice is inserted through the "eye"

This means that you aren't sticking your steel directly into the flame front that is still burning through the oxygen (as you do in "box" forges like the diamondback), in fact, you're not really using the flame to do most of your heating work, you're using the radiant heat off the forge liner to do the main job of heating your steel. This helps amatures like me keep decarb and scaling down a bit while we learn to shape knives in fewer heats. I keep the atmosphere just a bit rich in my forge, and keep the steel out of the yellow areas around the outside, and this really seems to help both get a very even heat as well.

Also, you may want to very seriously consider building your own forge. You can do it for half the cost of a premade forge, and end up with a product you will be much happier with in the end.


Also, do consider the source and his / her motivation when reading these things. Darren is a great guy, and I'm sure his forges are quite well built, but he (very rightfully I should add) deserves and thus charges a premium for the time and effort of building a forge. These folks at Ironback are ignoring the difference between vertical and horizontal types of circular chambers, and what the differences are. Why? basically, to convince you to purchase their own product, which, imho is an inferior tool to a well crafted home made forge. They DO have one good point though, and that is about ceramic fiber. Ceramic fiber is an INSULATION it is NOT a refractory. The inner walls of whatever forge you work wth should be made of a good, durable refractory, and that refractory can (read: should) be insulated further with ceramic fiber to increase its heat holding properties, and thus its fuel efficiency.

In considering the source, bear in mind that I have no vested interest in what I'm telling you. I don't sell any such product, nor do I build forges for money. I bought the stuff from which I made my forges mostly from Darren Ellis because his prices are good and his service is superb. If you are even remotely serious about forging your own knives, then I would suggest that the skills required to build a forge should not be beyond your capacity, or you risk disaster operating one. Be creative, be safe, and you will end up with a practically maintenance free tool that can outlast and outheat any of the commercial offerings.

Some great resources for building a forge include Ellis Custom, for materials and supplies, Yeoman machinery is an ebay store that has air blowers that work beautifully for forced air burners, at a great price, and Kevin Cashen, Don Fogg, Indian George, Tim Zowada, all have websited that are chock full of design ideas and problem solving tips for building a forge.

If you run into problems in the process, I'm around these boards every now and again, as are several more experienced makers. When I was having problems trying to get a VERY big forge up and running, I discovered Delbert Ealey is about as nice and helpful as they get, and he knows his stuff!
 
I've never tried one of his shells, and I don't know how they are. Last I heard was Ashokan two years ago, that Mr. Zowada had (at that time) only recently gone back to full time knifemaking. Also, I wasn't sure if he ever ade forges for sale, I thought he only offered the cast liners.

If you can locate one, I'm sure it'd run beautifully. Tim's a well respected maker in his own right, and some of the other big names (at least one, anyhow, who's opinions I have learned to trust the hard way) in the pantheon of modern bladesmithing have backed his design as a good one.
 
neat, drop him a line via his site, and see if he still sells them. It could very well be worth your while.
 
The main advantage to the swirl is keeping the direct flame off the work piece. I have tried square or rectangular forges and do not like them. It took a long time to come up to temp and then took a long time to recover. It was a whisper style atmospheric. Meant for farriers not bladesmiths.
 
I found myself agreeing with much of what I read at www.diamondbackironworks.com as long as you stick to the vertical concept, I have rubbed some fur the wrong way in the past when I expressed my opinions of the wool lined verticle forges, but that is because after working with many designs and settling on the horizontal cylindrical refractory design, the former basically defeats every goal or benefit I am looking for in a forge design.

With a refractory forge you get your heat from the radiated thermal energy of the shell NOT FROM THE FLAME. You also need to remember that there are different requirements in damascus making than general forging. If all I were to do was to forge blades to shape with no welding I would be quite happy with a wool lined forged that had uneven heat zones. Warm up time is minimal and in forging uneven heat zones can be used to localize heats. However in welding damascus the cheapest way to go is an investment in a good, durable, flux resistant refractory. And the more even the heating the better, the eye of that vortex is the most even heat I have found to date.

For working any high carbon steel and especially in welding, one critical feature in any forge is the ability to adjust the atmosphere. I personally would not own a forge that could not be quickly adjusted from carburizing, neutral or oxidizing flame. All have their uses.

As soon as you lay a cylindrical forge on its side anything that could be called hype becomes fact for me.
 
kevin i was just thinking of finishing my forge i started. but using 1" thick kast-o-Lite walls. its made from a small air tank 8"x16". but i cant decide if i should do a 6" chamber with 1" thick walls or a 4" chamber with 2" thick walls. will i need doors or is open ok. for doors i was thinking 1" fiber board fitted inside each end with a door hole. should the door hole be at the floor of the forge or at the center of the vortex. i want to get back into making damascus as well as using it to heat treat.
 
my first forge 8x8x16, steel shell and had 2'' insul brick sides, 1'' insul brick roof, and a poured lightweight castiable floor(best i found to hold up to flux) total bill with burrner and all was $18. second one was same design but i dipped the brick in 3000 soup then put them in. and it had a shell of 3/8 plate total bill $20.

I'd say if your layed off like i was at the time you gotta do what ya gotta do to get buy, and cant always afford to pay when ya wanna play. Use your resources,and local scrap and welding shops for the steel frame, the find a brick layer (which i am) that can hook you up with liner material (no cost) then all ya pay for is the burner parts(can all be bought at lowes) worry about the thermo coupler down the road. just my 2 cents.
 
JTknives said:
kevin i was just thinking of finishing my forge i started. but using 1" thick kast-o-Lite walls. its made from a small air tank 8"x16". but i cant decide if i should do a 6" chamber with 1" thick walls or a 4" chamber with 2" thick walls. will i need doors or is open ok. for doors i was thinking 1" fiber board fitted inside each end with a door hole. should the door hole be at the floor of the forge or at the center of the vortex. i want to get back into making damascus as well as using it to heat treat.
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I am not an expert in forge design, but I have found ones that work and have only had to work on shells twice in all the years I have used this design. Thinner is better, there is less heat up time and less cracking due to overly thick material heating at widely different rates. All refractory shells in this design crack but pressure applied from the outside hold it all together via the arc principle thus making them virtually indestructible despite the cracking. By far my favorite floor refractory is a high alumina white. I have made large chisels and hammered the hardened flux out of the bottom of my forge with this type, with no fear of damage to the shell.

Diameters always seem too difficult for many (either too small or too large). 8 inches seems to be about perfect for a proper vortex and for fitting work. Many seem to think that if they are going to heat larger stuff the forge has to be enormous, which will just waste gas and space. If the diameter gets too small the turn radius will be too tight and too close to the work for an even vortex.

I personally really prefer enclosed ends with a door just large enough to accommodate my work. Some of the most inefficient forges I have worked in just have a pile of bricks at either end. The door really should be in the center in order to keep the work out of the vortex around the outside, or you will get the exact problem described on the www.diamondbackironworks.com
page. The bottom of the door makes a nice work rest, holding your piece in the center of the heat.

I Like a wall thickness from 7/8" to 1-1/4" and cast my end pieces with doors in the same manner. The fiber board, I have a supply myself, is no better than wool at handling the wear and tear of welding and forging. I have tried using it for door plugs on the back and found that wool stood up better than it did to the flux and poking.
 
Kevin R. Cashen said:
For working any high carbon steel and especially in welding, one critical feature in any forge is the ability to adjust the atmosphere. I personally would not own a forge that could not be quickly adjusted from carburizing, neutral or oxidizing flame. All have their uses.
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I agree! :)

I think controlling the temperature and the atmosphere are the most important...

One question though,...When do you want an oxidizing atmosphere?
 
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