Already Own a Coal Forge, Why Should I Switch to
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I am just starting out. Which kind of forge should I build?
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Should I buy or build my new gas forge?
I am asked these questions so often that I have decided to prepare a separate web page just to answer them. Now to start out let me say that I was a coal forge smith for many years. I have four coal forges, two rivet forges, a full sized Buffalo #660 shop forge, shown here the day I brought it home, and a large home made expandable tuyere coal forge that has served me well over the years. My big home made forge has almost any feature you could wish for in a forge, an expandable tuyere to change fires from a 6" diameter to as long as 24", separate electric and hand cranked blowers, built in crane, a built in hood with 12' chimney, is easily portable, can handle iron up to several hundred pounds in weight or in long sections, and has its own post vise! So why would I want to switch to a propane fired gas forge if I have a coal forge with all these capabilities? Hopefully the following will answer this question, as well as any others you may have. One last comment before I start into this discussion, when I say "gas forge" I will be using that term generically to include both propane and natural gas. I will make a few comparisons between these two options further on in this document also.
I was totally satisfied
with using coal until I visited a blacksmith friend of mine in Oregon
summer a number of years ago. He had built a crude but very effective
gas forge that was fired with an equally crude but equally effective
burner, and the burner was made all of off the shelf plumbing fittings!
was astounded at the temperatures the forge could reach, and the
of the little 3/4" burner. I was totally sold on the little forge when
performed several basket welds, and did it much more easily than I
in my coal forge. I copied down his burner design, and that started the
road that eventually led to the various Web pages, and various forge
burner designs, you see here on my site. I will include a URL list at
bottom for most of my major web pages relating to blacksmithing or
work. From these pages you will be able to link to all the peripheral
I have, such as the one you are presently reading.
I have to include one reason to use gas that is probably the most compelling one, your health. One day after a full weekend of smithing work, using one of my open pan forges, I awoke with a very violent shaking of my muscles in my arms and throughout my body. I went to the doctor of course, and after a lot of testing and discussion they determined I was suffering from nerve poisoning due to breathing too much coal smoke. There are some bad things in coal smoke, especially various sulfur compounds, that can attack your central nervous system, as it had done to mine. I was informed that if I continued to breath coal smoke I would end up with permanent and non reversible nerve damage! Fortunately this happened at the same time that I was becoming familiar with the magic of propane forges. Following that experience I have fired up my coal forges no more than three times, when I had to heat iron that was too large or angular to fit in my propane forge. BTW, there is a solution to that inherent problem, which most propane forge possess, and the solution is the "Clamshell" forge design, which I have information elsewhere on my site about. I have a Zip file of information about the Clamshell that you may download if interested. Ralph Sproul provided me with some of the images in the Zip file, as well as a copy of his very well done Clamshell forge plans. I highly recommend you contact Ralph if you are interested in this forge design. Nahum Hersom provided me with information that is in the file too. It is a well known fact that no forge design can do everything, but the Clamshell is probably the closest to being a "do-all" forge design as exists.
Probably the most asked question, and the least important one, regards economy of gas verses coal. Economy can be gaged in a variety of ways. If you wish to compare only the cost per BTU delivered to the iron you are working on, then the various burners on my pages will win hands down every time. Blacksmithing coal is becoming more difficult to obtain, with ever rising prices, but this is to some degree a function of where you live. Also, coal of blacksmithing quality is becoming very difficult to obtain because of various mine closings due mostly to increasing Federal regulation that coal mines must comply with, and also because most of the high quality coal comes from relatively small mines that are finding it tougher to compete with the larger mining operations. Where I live, in the mountains of central Idaho, I have to drive 400 miles to Portland Oregon to purchase my coal. Granted, I take my trailer, and combine these trips with visits to relatives and friends in Portland and the Willamette Valley, but it is still costly to haul 800-1000 pounds back to Boise and on up to wher I now live, and the price of the coal in Portland is not cheap to begin with.
To really evaluate the economy of propane to coal you have to look at a lot more than just raw fuel cost. Gas forges, either propane or natural gas, allow constant observation of the work during the heat. Also, they can't burn the iron, as coal will so easily do the moment you look away for some reason. Gas forges do scale the iron, but not as badly as coal if the forge is properly built and adjusted, and gas will make all your work cleaner and speedier. Forge welding in a gas forge is much easier for the beginner, but not greatly different for the accomplished coal smith. With a gas forge you can start working instantly, the moment you light off the forge. You do not even need to wait for the forge to warm up to working temperature. With a coal forge you will spend a significant amount of time tending the fire and getting it ready for the days work. I would like to refer you to an e-mail I recently received from a fellow regarding his conversion to gas. Dan states very clearly that with gas he now spends his time forging instead of tending the fire. Dan is a new smith, and most certainly a smith with long experience will handle a coal forge with much greater expertise than someone new to blacksmithing, but Dan's comment "I would spend more time trying to manage my fire than I did hammering." is still valid to some degree even for the expert.
The real bottom line that you should look at when comparing coal to gas IS the bottom line. With a gas forge you will be able to produce more forged items per hour spent at the forge, no two ways about it. Also, for the non expert smith, and that includes almost all of us, his level of ability, his apparent skill level, will increase with the gas forge due to the comparative ease it provides when performing many of the different blacksmithing techniques, especially forge welding. Now, if you are starting into blacksmithing because of the mystique of the burning coal, and its connection to the smith and smithy of long ago, then perhaps these comments don't apply to you. If you want to play with the fire and smell the coal smoke, then by all means buy or build yourself a coal forge. I have ample coal forge designs linked on my Design page for you to explore. You can be hammering iron at the end of one weekend, or even one day, by building a coal forge, while a properly designed and constructed gas forge and burner will almost certainly take longer than that to complete, of that there is also little doubt.
One interesting benefit of building a gas forge yourself, verses buying one, is that you can easily build a far superior forge to any commercially produced gas forge on the market. This will not only provide you the pride of ownership of a superior tool that you built yourself, but it also sets you up as a knowledgeable technician to repair or modify your forge as needed. Very few guys who have spent $1000+ on a commercial gas forge will want to cut into it to make modifications, but you will not feel in the least restrained from doing so on your own home built forge if you suddenly happen upon an improvement that will make your forge function better for you.
Another factor to be considered, and perhaps the one that may be the most important for many new blacksmiths, is the user friendly nature of gas where your neighbors are concerned. Unless your neighbors are a lot different than mine when I first started out, they will not appreciate the acrid coal smoke of "start-up" drifting in through their open windows on a warm Saturday morning. I can easily start up my coal forge with almost no smoke being produced, but I have been at it for many years, and there is still the ever present coal smke smell even without visible smoke. It may take you quite a while to master your fire, and I would say that it almost certainly will smoke heavily in the beginning. With coal, all your neighbors will be alerted to the fact that your smithy has started operating, by the tell-tail column of smoke above your forge, and in some locations that can bring you a visit from the authorities in short order. With a properly designed burner and gas forge, the neighbors will not even know you are firing up for a day's work at the anvil. The only thing you will have to overcome then is the noise you inflict upon them, and hammering on hot iron isn't nearly as noisy as you may think. Usually arguments to your noise, if there are any, can be overcome with the occasional gift of a piece of your forge work to the cranky neighbor who is giving you trouble. Noise is less of an issue than coal smoke for most people.
Although I have covered this elsewhere in my forge pages, I will mention it here too. Many guys have the mistaken idea that gas forges can't forge weld, even some very experienced smiths believe this. The link is to an e-mail which points this out clearly toward the bottom of the document. In fact, quite the opposite is the case. Gas forges that are properly designed will very easily forge weld if they are equipped with a properly designed burner, and enough burners, or big enough burners, for the volume of the forge chamber. I have a series of burners posted to my design page that are so hot that you have to take protective measures to prevent flash burn from the light emitted from the forge chamber! Please see the safety warning at the top of the Mongo Burner section. These burners must be used with great care, but the standard work-horse burners I have posted, the "Reil & EZ Burners," do not present this hazard unless used at very high gas pressures, and they can forge weld and easily melt cast iron.
I would like to make a few comparisons between propane and natural gas fired forges. I admit that these comparisons do not hold for all forges of either type, but some generalities can be made. Because natural gas is obtainable for most people only at very low pressures, 4-6 ounces, naturally aspirated Venturi burners, such as found on my pages, are not an option. Natural gas burners almost always need blowers. I was fortunate when I lived in Boise because I had access to a 10 psi tap off my natural gas line, and the work of setting it up for use was all borne by the gas company. I only had to provide a regulator for the gas line. Most people are not so fortunate. Blown natural gas forges tend to be very "blowy" and have a very pronounced "dragon's breath." This blast of hot gases coming out the front of the forge can be very uncomfortable to work around. Some smiths attempt a fix by mounting an additional blower below the forge opening pointing straight up to blow the dragon's breath upwards and away from the smith. Also, many natural gas forges are poorly tuned and provide an oxygen rich atmosphere in the chamber, causing excessive oxidation scale to form on the iron. This however is not a fault of the forge but of the smith using it. Due to the blower they also tend to be very noisy. Also, but not always, they tend to run at lower temperatures than a propane forge, although forge welding is well within the range of a natural gas forge. I have a friend who does all his Damascus welding in his natural gas forge, one I sold him a number of years ago. Lastly, and on the positive side, natural gas is a less expensive fuel to fire your forge with, and you do not need to go refill tanks periodically, but its also not portable.
Propane forges tend to run hotter than natural gas forges due to the difference in energy content per cubic foot of the respective fuels. Propane forges fitted with naturally aspirated burners are very portable because no electric blowers are required. They have a lower total gas volume entering the forge chamber, so the dragon's breath is reduced or eliminated almost all together. If adjusted properly, and equipped with a choke as shown on my Design page, propane forges can run with atmospheres that almost totally eliminate scaling of the iron, but well regulated natural gas forges can perform equally as well. I consider both propane and natural gas to be very good fuels for gas forges, but they must be selected with a full knowledge of the advantages and disadvantages associated with each fuel, otherwise you may be in for a disappointment.
The initial cost of forge construction may be a factor for some people. Although you will quickly be repaid all your additional expenses involved with building a gas forge, verses a coal forge, through fuel and time savings, you may still desire the cheapest way possible to start blacksmithing, and coal is the winner, hands down. You can start with nothing more than an old truck brake drum, or old BBQ pan, and an old hair-dryer, and be forging before the day is out, even using high sulfur "junk" coal. Gas forges can't compete with that. However, the savings realized in fuel costs, and the other less tangible benefits, makes the gas forge the clear winner of this argument in the long run. I can think of only two reasons to build a coal forge; to play with the fire, and smell the smoke! Most certainly I started that way in 1958. The attraction and mystique of the blown coal fire is undeniable, and I hope that facet of blacksmithing is never forgotten. It is our heritage as blacksmiths, and that connection should always be in the back of the mind of any real blacksmith, no matter what fuel he is using.
covered only a few of the benefits of using gas to forge with. Most
one is the pleasure you will derive each time you fire up your forge,
it responds with that familiar low roar as it turns a bright
inside. You will take pride in knowing that you have a forge as fine as
you can buy, better in fact, and you built it all yourself. If you
you can even equip it with push button start. I hope you will use the
on my pages to select and build a forge and burner system that will
you well for many years into the future. Here are some URL links to a
of my resources. I hope that this page may have helped you in your
as to which type of forge to start with. If you really become involved
iron you will soon be the proud owner of a number of forges of both
The Full Site Map - Lists All Pages on This Site
My Home Page
& Foundry Page
and Burner Design, Page 1 of 2
Note: I no longer provide e-mail help or support for burner or forge construction.
Page By: Ron Reil
©Golden Age Forge
5 Mar 06