Latticino

I still see myself as a beginner at blacksmithing, but I have around 30 years as a mechanical engineer in the construction world (BSME and PE certification). I also have an MFA in Glass from a studio arts program and was a professional glass artist supporting myself from that craft for 10 years. I have been responsible for building a lot of glass equipment and that transfers well over to forge building. Also a voracious reader, go figure, but though I was intrigued by the SCA could get my head around all the Thees and Thous...

I'm more expert regarding gas forges, so take this for what it is worth. As Thomas mentioned you might be better served by looking at some of the already worked out forge designs illustrated elsewhere on this site. There is tons of great info in the section on solid fuel forges. Not sure why your time searching is more valuable than mine writing, but I'm feeling generous today. I've never used a coal forge that didn't have a firepot for concentrating the coke produced. Looks to me like your configuration could use the liner recommended by Thomas to, at minimum, level the bottom of the forge and close up the holes left by the drum configuration (I'm a fan of rammable refractory, but it does cost...). Personally I would probably include some level of Duck's nest at the air exit point. Clearly you will need some kind of blower and connection to same from your Tee fitting. The necked down size and gate valve are a bit overkill as regards flow metering, so hopefully you have a blower that will push around 140 CFM if you plan on getting a larger fire up to welding temps. You also will probably want to put in some kind of grating at the floor of the forge to keep the fuel from dropping down the air blast pipe. A clinker breaker is nice, but I've heard good things about a simple grid of 1/2" bar. If you are going to use the forge inside, and possibly outside as well, you will probably need to make a hood to direct the heat, smoke and fumes away. The side draft type work a treat and aren't that hard to build. Finally you will need to make an ash dump gate for the bottom, so you can clean out the dirt leg and keep the air going the right way.

Excellent point, and I agree completely. Sorry I didn't get into more detail on the potential failure modes of using an isolation valve for flow control. Needless to say, for safety it a very good idea to have both. I just was noting that using the isolation valve for flow control was also a bad idea because it doesn't work well as a metering valve. Note that for complete disclosure there is also a phenomena called wire-drawing that occurs when an isolation valve is used for a long period for flow control and the small opening left results in high velocity fluid flow at the resulting orifice, which is not designed for same. With the solids and condensates that Frosty mentioned rushing through this orifice at high velocity the seat gets eroded, leading to lack of ability to provide positive closure. I'm not that familiar with the mechanism that Frosty is referencing for abrasion on the valve seat, but this wire drawing is a common result of misuse of isolation valves, especially in steam systems where use of the wrong type of metering valve is more common). Also, I don't know about your neighborhood, but around here code compliance requires both an isolation valve and flow control (pressure regulator), for gas piping installations.

You can adjust the quantity of propane with a conventional valve, but it is very difficult. The valve opens too quickly to be accurate, a very small change in handle position makes a great change in flow rate.. That is why regulators, with multiple turns to open slowly (called control valve authority), exist. Spend a few extra bucks to get an actual regulator with a pressure gage. Trust us, it is worth it.

The ABANA periodical, Anvil's Ring, lists a number of blacksmithing classes. Google works also...

Yummm, anvil porn for sure. That thing looks almost naked without a couple of edge chips and face scratches. I'd gladly bid on it as well if you were only closer.

No worries, just didn't want anyone getting hurt.

As a former professional glass artist I have to add a couple of cautions regarding this. Please note that I am following Frosty's typical instructions regarding terminology (i.e. getting it right aids in communication). There are many different types of glass, and each has a rather different coefficient of thermal expansion. If you don't get one that has a similar coefficient to that of the material you are attempting to marry to the glass you are asking for trouble. This trouble can range from a minor crack in the glass to more "explosive" reactions, to some extent depending on whether the glass is encapsulated by the metal or surrounds it. Even composites that appear to be stable can react badly to exposure to varying thermal extremes down the road, or to what appear to be minor scratches (check Prince Rupert Drops out for fun). The marbles that Frosty has mentioned could be either lampworked style borosilicate glass (like Pyrex, which is a lot more forgiving) or bottle type soda lime silicate glass(beer bottles, off hand blown glass...), which is not. Either type needs to be annealed, not tempered, to be safe for ongoing use. Checking the final product with a polariscope until you get your annealing sequence down is pretty critical (http://www.glassalchemy.com/building-a-polariscope). Note that annealing glass is more similar to spheroidal annealing of steel that just throwing it into a barrel of vermiculite. Controlling temperature at a slow rate as the glass cools down from around 915 deg. F to around 200 deg. F is critical for success. I have found that glass/copper mixes tend to be a lot more stress free than glass/steel mixes. Not sure if it is just the flexibility of the annealed copper, or a more close thermal expansion coefficient between the two. Of course most of my experience is with soda lime silica glass, so YMMV. I believe that there are a couple of other glassblowers/smiths participating on this site as well and hope that they chime in with their experience. Needless to say there are certainly methods that can be used to echo Chihuly's organic glass forms in steel, just not glassblowing methods (though I have seen steel vessels "inflated" using compressed air to interesting effect). Chihuly's floppy forms take advantage of differing thicknesses of glass deforming differently under the influence of heat, centrifugal force and gravity (or is that centripetal?...). More organic manipulation of metal is certainly possible using the first two properties, but somewhat direct manipulation of the material is needed to mirror the others.

As others have said, and I believe I mentioned in one of your earlier posts (unless the forbidden bug got me that time), compressors are not blowers, or appropriate for either solid fuel forges or gas forges. The blowers we are looking for have relatively high volumes of air moved at relatively low pressures. Compressors do the opposite and a small one like that isn't likely to be rated for continuous duty in any event. The type of bellows you are showing is very likely not to be appropriate either. If you have seen any "real" blacksmith bellows, they are usually considerably larger and "double action" (pumping air on both the upstroke and downstroke). Depending on what kind of solid fuel you plan on using I would be surprised if those will work, and they will almost definitely not work for a blown gas forge. I strongly suggest you take a class in knife forging if you plan on going that route. There are several craft schools in your area as well as some smiths that teach knife making. Getting some direct instruction will cut short your path to making a successful knife by a considerable margin. If nothing else, you should look into going to Ashokan for the fall knifemakers gathering: http://ashokancenter.org/events/sept-18-20-new-england-bladesmiths-guild-seminar/ As far as a source for knife making steel, you are close enough to go to Aldo: http://newjerseysteelbaron.com/

Don't have anything to add to the rural farmhouse stories as I'm a suburban fellow (though I do live in the snow belt). However, as regards your gas forge design, a bunch of the folks in my local blacksmith group built gas forges that were "D" shaped, with the flat side of the D facing down. This flat side was indeed made of high temperature INSULATING bricks, not hard fire brick which will be a huge heat sink. If you must use hard brick for the floor, I would recommend going with splits (that are 1/2 the standard thickness) with the same wall thickness of insulation used for the walls underneath. Needless to say these insulating bricks are almost as prone to being eaten away by flux as insulating glass fiber, so some type of protection for that surface is recommended (thin kiln shelf, bubble alumina coating, cast Mizzou liner, high alumina split bricks...). The forges that were built used single side firing blown burners with small squirrel cage blowers from Graingers or the like, and I believe worked quite well. One nice aspect to the design was the ability to remove the entire top section of the forge body to allow replacement of the floor with inexpensive and easily available insulating bricks. Looked pretty similar to the floor of Frosty's forge shown in recent photos on this site.

Saw Tom Latine forge one up quickly in a recent class at Touchstone and then use it to split down a number of hammer handles from log stock. Worked extremely well.

You are joking regarding the magnesium burner flares, right? Might want to check the flash point on magnesium first. Even though the flare is cooled by the combustion mixture going through it while running there is always a chance you might shut off your burner while the forge is still at elevated temperature. Since it is naturally aspirated that forge temperature will certainly heat up the flare.

Sounds good, but have a couple of notes. First, at the velocities we are talking about I'm not sure that turbulence inside the mixing chamber is an altogether bad thing. I see this turbulence serving two functions: first more thoroughly mixing the air and propane, and second potentially reducing the friction effect of the pipe walls to flow (Note that laminar flow is not always your friend as far as friction in piping goes, and no, I'm not going to go through all the calculations to figure the correct Reynolds number to validate this at this point, just going with my gut). Of course it will probably not be a big deal if you want to bore out the weld seam on the pipe, it could work to make the flow more uniform and symmetrical. Just seems like added work to me, but would be interesting to have a side by side comparison. Second, you may find that a threaded fit for the flare is a better idea. There is going to be a lot of thermal expansion and contraction at that point as you cycle your forge. A slip fit, like you are suggesting, may not hold up without some kind of further mechanical method of joining. Typically I try to keep the far end of my flare just inside the first 1/2" or so of the forge insulation, with a small annular step protecting the edge of the flare. Third, I'll let Frosty make a final decision here, as it is his burner design, but as far as I know it shouldn't make a great deal of difference if the mixing portion of the burner is a bit longer than specified. There should be a minimum length for adequate mixing and "flow straightening", but I don't see how an extra inch would effect the burner operation unless the induced flow from the ventauri doesn't have enough static pressure to overcome the extra pipe friction in the mixing chamber.

Looks more like a compressor than a blower to me. If coils are copper may not hold up to forging temperatures. Will be an interesting experiment.

I use a short, light Kevlar glove on my left hand. Works a treat and is much more heat proof than leather. Strongly recommended.

Probably major overkill, but you can source single wall SS kitchen exhaust duct from numerous manufacturers. Here is one at $42 (US) for a flanged 2' section: https://www.floaire.com/catalog/ShowPartDetail.asp?catid=371&CalledFrom=C I used a, safely, cut up helium tank from a balloon animal kit for one of my gas forges and a Harbor Freight compressed air tank (I think it was the 11 gal model, and I got it very cheap because the gage was broken off...) for another. IMHO, unless you plan on leaving your forge outdoors in the weather (and then you will have plenty of other issues to deal with regarding the insulation), there is no real need to go with a stainless liner. In fact if you are willing to coat the outside of the unit with furnace cement, and live with a little cracking, you could probably get by with a forge made of chicken wire around the 2" of frax insulation. The shell is really just there to support the insulation and burner head, and there are a lot of ways to skin that cat. On the other hand a stainless flare for your burner is a very good idea, unless you are casting the burner flare out of refractory (Mizzo works great for these). With the chamber length you are looking at a ribbon burner might be a good option, but then a more advanced burner design might be in order. No detraction on the Zoeller or T-burner designs, but they may not be optimized for the backpressure from the small ports required for the ribbon burner.

One of the banes of pattern welded steel, especially for a new maker, is inclusions. Even experts can get these at times. Needless to say it is a shame to have an inclusion in a knife or sword, but to have one in a gun barrel... That sounds like a recipe for disaster. Smelting steel from ore can have similar issues. As a machinist you have been spoiled by modern steels and large equipment. With your skills a more approachable goal might be to look into stock removal for your weapon making. I think one of the experienced knife makers on that Forged in Fire show resorted to stock removal to make his weapon when faced with a sword configuration he was not used to. Sword making is significantly more difficult than knife making. I applaud your enthusiasm, but your timeline is pretty ambitious. In addition to the perils of forging up a pattern welded blank the size you need for a sword, you need to deal with forging long tapers, accurate bevels, a fuller or two (not required, but I'm sure with your aspirations you will want them as well), grinding or draw filing the bevels and then properly heat treating without warp, corkscrew or sabering. That doesn't even include all the design work that is required to have a sword (with reasonable weight, tapers, weight distribution, pommel size, center of percussion...) instead of a sword like object as your goal. Your press will certainly help, but until you learn how to use it effectively it will just be a tool for screwing things up faster. Pressing one billet while heating the other sure is an efficient way to make pattern welded billets, but I didn't get the idea you were going into production... That being said, I don't see anything wrong with a forge interior that is 10" long by 8" diameter. As long as you are willing to "waste" a certain amount of fuel while you attack the learning curve, and put in enough burner to get it to welding heat (that you will need for pattern welded blades) you should be fine. Strongly recommend you get Jim Hirusiclas (sp?) books and study them.

Hard to tell from your photo, but is the eye a complete cylinder? If not the force of using the tool will work that wood loose in time. I would probably term this a tomahawk based on the eye shape, but that is just nit picking. The shape you have achieved it pretty good for a first effort, good job spreading the edge laterally. You probably have not done any heat treating as the girder used is most likely not high carbon steel. Edge retention will be limited due to this, though it certainly matches some of the period hawks that were used as trade items here in the states. Better tools had hardened steel pieces forge welded to the cutting edge to act as bits.

Been wondering about this also. With the numerous blades that have shown up with cracks on the show I would have expected these expert blade smiths to at least torch temper the spines. Based on the typical requirement for both chopping and slicing capacity I'd probably temper fairly aggressively. I think that is just as exciting to watch ( especially if they could capture the color change and have the expert commentators talk about why this is critical) as seeing yet another crossection reduced in the press or power hammer. It does appear like the smiths are often quenching their blades in the last 10 minutes of their allotted forging time. You would think leaving that 5-10 minutes to either torch temper or tong temper would be prudent. Of course what I would really like to see is demos of austempering, marquenching and Cryogenic hardening, along with detailed analysis and descriptions, but can see how that might not be as interesting to the general public.

Forging looks great. Hope you left enough meat in there to make it through heat treat successfully. Chef's knives on my bucket list for sure. Will look forward to seeing this one completed.

Can see why they are thrilled with this. Lovely work.

Sidewall exhaust fans, set up high in the peak of your shop, are the bomb for venting the shop. They are best for high volume of air at low static pressure (basically the opposite of what is needed for a forge blower). Get one with a back draft damper/louver if possible to keep out the cold in the winter. I now like the Greenheck SBE line (belt drive, steel prop), but there are plenty of others out there. To get the recommended 10 air changes per hour in a 10' high shop of the size you mentioned you only need 800 CFM. That is a 2' square fan with a 1/4 HP motor. I think I originally got mine from WW Graingers. Remember to have somewhere for the air to enter the shop as well...

If you ever plan on moving/lifting anything substantial, you may want to consider bulking up your framing in one section of the shop where you could hang a cheap electric or chain hoist . Sure wish I had something like that in my shop.

RR Track (2'length at least) set vertical with the "end" surfaced flat tied onto a post firmly mounted into the ground. Search this site for rail road track anvil info (best I've seen for general use is here: http://www.iforgeiron.com/topic/42290-another-rail-road-iron-anvil/ , but you can certainly get away without the extra work making a horn).

Suggest that you take a beginner class or two first to find out if you have the bug for blacksmithing, rather than build a forge. Getting some of the fundamentals down from a competent teacher is orders of magnitude better than trying to reinvent the wheel (though it does appear that you have been doing some good research online as you were aware of the depth of your fire being an important part of forge design). There are a bunch of other fine nuances for constructing a coal forge (method for introducing combustion air - including flow rate, orientation and configuration, vent stacks, clinker breakers and ash dump), but you can certainly get by on a shoestring with a blow dryer and capped steel pipe with small holes drilled in it placed in a shallow trench in the ground if need be. If it were me I would try to experience using some coal forges that have been well constructed before putting any significant effort into building one, but each to his own.