HWooldridge

Ed, I've had it happen three or four times. In one case, I forged the tenon - 1/2" square from 3/4" square and punched the hole in the upright, then fastened the two pieces. The tenon broke right at the shoulder. To myself, I whispered, "No problem, I'll just shorten it a bit", so I cleaned it up and did another - that one broke too. By this time, I was uttering epithets. They did not break early in the process but as I was finishing with "faceting" blows on the head. At the time, I theorized this may have been caused from a bit of bending to and fro but the fastened piece was well seated. What seemed to help was not localizing the heat too much on the end of the tenon. In other words, the entire end needs to be hot down into the shoulder - not yellow but at least a dull red. I think my problem was that the shank was too cold and eventually just work hardened to the point it broke off. Didn't matter that I had a radius in the root - it still was enough movement to break. Just my observations but I'll listen to other explanations...

I have had trouble with tenon joints breaking off on andirons. I observed good forging practice and left generous radii everywhere but the piece would often still break. However, it may have had something to do with my technique. I fitted the pieces, heated with a torch and hammered away. As the joint cooled, it would often stress to the point that the tenon pulled away from the parent stock (broke right at the shoulder). I now heat the whole end in the forge just to get it preheated, then use the torch to heat the tenon. The loose part is dropped over the top and the rivet head formed with the hand hammer. I find it best to use two heats so the contraction does not overstress the shoulder from trying to finish too quickly. Has anyone else had the problem? I was fastening 3/4 square to 3/4 square at a 90 degree orientation - square tenon thru a punched hole.

The only thing that burns on any solid fuel is the surface. Therefore, it makes sense that smaller sizes will yield more heat for a given volume of coal. In other words, throwing 4-5 fist sized chunks on the fire will not provide as much surface area as those same few pieces broken down to pea size. However, those large chunks will burn longer before they are consumed (same as firewood). For years, I have used coal that was about 60% fines and the rest large chunks. This worked OK but I had to make a slurry and pack the mass into the fire so it would coke. Later on, I was able to get my hands on some that was about 95% in the size of 1"-2" with the rest being fines. This made a hotter fire and was easier to see into for both welding and general forging. However, it was not from the same mine so the major difference may have come mostly from the composition and less from the size.

The answer is theoretically "infinite" below scale temps but as the other folks have stated, burning and/or scaling will influence the final result. I have tried to measure the thickness of scale with a micrometer and gotten a number around 3-5 thousandths. If a bar that is .500 in diameter is taken to scaling heat every turn in the forge and the scale is removed once, then an average of .004 x 2 (scale on both sides) would mean you could heat it 62 times before it went away. In reality, it is not linear and you can lose a great deal more because heavy scale will be thicker, forging will obviously reduce the size, high heats will generate multiple layers of scale, etc. From personal experience, I have also left pieces in a gas forge for a long time and observed much more real reduction in size from scale loss than in the math exercise above, so the reality is that one VERY long and HOT heat may be enough to ruin a piece - even below temps where it is burned. To answer your question - it's more about experience and observation. As Ed said, get it hot and move as quickly as you can while retaining the quality of the work.

A typical rectangular pot sits on the lower lips - the higher ones are used when the hearth is bricked. You can cut a hole as described, drop the pot into place, then put a layer of fireclay in place. I wrote the following for "the place across the street" a while back - there is also some other info buried within that might be useful to someone... By Hollis Wooldridge 2/11/05 Lining a Forge: I lined a Buffalo forge that has the lips an inch or so above the iron hearth and it turned out well. The process is based on something I learned years ago when I used to help my grandpa build houses. In addition to carpentry, he did some rock work and one thing we would do occasionally is reline fireplaces. On horizontal areas, he would make up a mix, apply it dry and level, then spray water on top. This would rock up in a day or so without cracking. The mix I used (based on his recipe) was 3 parts mortar, 3 parts clean sand, 1 part fireclay and 1 part dry lime. I mixed it, poured in the hearth to a depth that was flush to the top of the firepot and raked it smooth, then sprayed only enough water on it until the surface was wet. I let sit two days before making a fire and it had hardened nicely with no visible cracks anywhere. I think the minimal amount of water helps eliminate the cracking. Coal Forges: I have seen more badly constructed coal forges than good ones in my life. A lot of folks make their own (which is perfectly fine) without a basic knowledge of not only how but why it works. All solid fuels need some amount of air pressure to burn properly. You can have too much velocity with insufficient pressure or too much pressure without enough air movement. The two extremes can be illustrated by a couple of examples. A light wind blowing on a campfire will make it hotter but only the outside of the fuel pile burns because the breeze can't make it to the interior. Conversely, hooking an air compressor to a firepot will make a fire but any amount of pressure much over a few pounds will blow the fuel out of the pot. The reason why bellows and centrifugal fans work so well on a forge is that they generate the right combination of both air supply and pressure. Too big a blower (like a large, electric squirrel cage) will lead to excess fuel consumption, more clinker and an oxidizing fire. In addition, a squirrel cage can be "stalled" because they are designed to move large amounts of air - not push it thru a mass of burning fuel. Conversely, too little air will never allow the fire to reach its proper potential for heating. The proper size air inlet to the fire is also important. I'm sure a lot of folks have used grates drilled with a bunch of holes but 1-3 larger holes is better. One of the best homemade firepots I ever saw had a 1/2x3" slot cut in the bottom. The pot was entirely made from 1/2 inch steel plate and there was no clinker breaker. This arrangement made a nice hot fire with a center about the size of a grapefruit, which is about like a commercial pot. I recently exchanged notes with a professional British smith who uses a side blast. It is simply a piece of 1" heavy wall stainless tubing as a tuyere and aimed slightly downward into a molded mortar "duck's nest". The coal is piled up in the hearth and forms it's own bed in the depression. Other fire shapes can be made by employing fire bricks to redirect the blast. This simple arrangement works well and eliminates all the Rube Goldberg creations that get built in back yards. The smith said he can easily weld with this design and some of these forges have lasted over 5 years in daily use. I use a coal that generates a big clinker in a hurry but it was cheap, gets hot and cokes well so the only disadvantage is the dirt. Therefore, I have learned to build a fire and use it for half hour or so then let the clinker cool for a couple of minutes. At this point, there is enough to usually pick up in one piece while I try not to disturb the coke around the pot. I can usually clean the fire and get back to work without breaking the whole fire down. If I have one piece of advice about fire tending, it's that less is usually more. I have seen a lot of people that tear the whole fire down on every heat or spend the entire time digging up the coke ball. A fire has to form a natural bed to work properly and it takes a few minutes for this to occur. A good coal smith will replace the piece for the next heat and rake a little coke on top. As the fire burns hollow, the sides are pushed in a bit. This gentle management is done during every heat - you don't work for an hour and then tend the fire all at once.

I don't use one but the only thing that comes immediately to mind is an electric furnace - but - the electricity usually comes from fossil fuels. I know every little bit adds to the problem but I think you could shoot every blacksmith on the planet and not make a dent in global warming. Cars are the primary culprit.

Here is some 'devil' humor: A fellow died and went to the bad place so he was moping around. Satan noticed it and asked what was wrong. The guy replied, "Well, I'm kind of depressed because I'm in Hades". Satan said, "Do you like poker?" Guy replies in the affirmative, Satan says, "Well, Monday night is poker night. You can play all night long, no table limits, we give you $666,666.66 every week to spend on chips." The man cheered up a bit and the Devil continued, "Do you like to drink? Wednesday is happy night - anything goes and you get anything you want. We have 666 kinds of single malt scotch just waiting to be tried." By this time, the guy is smiling broadly. The Devil then asks, "By the way, are you gay?" The man looks puzzled and says "No" - why?" Satan says, "Hmmm, you're probably not going to like Friday night..."

Go check out the thread in Shop Hints on the same subject.

Glenn, Interesting you bring up the gas welding because it reminded me of something I do occasionally. Once in a while, I have a little production job that requires welding 1/4" square together into a cross pattern. I take the two pieces, tack with a TIG, then hold with tongs and heat lightly with an O/A torch (usually a cutting head set on neutral flame). When it's red, I flux with gas welding flux, heat to bright yellow white and smack it together with the hammer. This does not make a classic forge weld but the pieces do stick quite well and won't pull apart.

I have to confess that I have had more frustration and failure at forge welding than anything else I have attempted in blacksmithing. Some people say heat treating is hard but it's a cake walk from my perspective compared to making a good looking forge weld. Over the years, I have arrived at some things that work for me. A few mirror previous comments, while others may just be my take on it. The absence of clinker is important because it restricts air flow. I typically make a fresh fire and get all of the upsetting out of the way early - by that time, the fire is about right to weld. I bring the blast up pretty quickly at first, so I have a yellow-white fire to my eyes. When the piece(s) are red, I remove and flux. I know some people flux in the fire but that does not work for me and I use EZ Weld or any commercial equivalent - I don't like plain borax. I put the pieces back in and cover with coke to the point I can see the tips. In addition, (depending on stock size) I leave about 3-5 inches in the fire so the rest of the stock is plenty hot and doesn't suck heat from the weld area. I leave the blast pretty high until the pieces start to blend with the fire's color and then throttle way back. Depending on stock size, I let the pieces soak for some seconds with almost no blast. The fire does not cool immediately so the pieces tend to continue heating. At this point, I usually see a few small sparks coming out of the top of the fire so it's time to remove and go to hammering. The weld typically goes "spat!" and sticks. If it does, I attempt to finish the joint - if not, I let the pieces cool completely and then grind away the resulting scale to bare metal. I have rarely been able to make something stick on subsequent tries without cleaning but by not beating the H@#$ out of it, I can usually save the upset. If it sticks but gets cold, I take another welding heat and finish the joint - because I have had a couple welds break from forging at too low a temp. Another thing I began doing to make the joints look better on butt welds is to feather the scarf tip to a point - rather than a chisel edge. I used to upset and draw the tip to run straight across the stock for the full width but noticed I would often get a nick or cold shut mark, which would sometimes peel if I was twisting through the weld area. I began experimenting and eventually just starting drawing a point. For me, this does not burn as easily and also blends better to the opposite piece. Using this technique, I can sometimes finish a weld in one heat and make the weld line disappear - although it can be a benefit to let it show (that way, you can show the client that it was really forge welded). The "point scarf" also works well on faggot welds when you are making a closed loop. I sometimes do a public demo that involves welding 1/4 square in a loop and then cutting apart to make a fork. This method leaves a nice transition at the union without causing a cold shut. I do not make knives so do not pattern weld - all of my work is typically sticking bits of steel together to make ornamental stuff. I'm sure the pattern welding folks have different techniques.

I'm not dissing your idea of using railroad track but if you can get tons of mild steel, buy a square block and weld a piece of scrap spring steel the the top. As stated elsewhere, the main problem with a railroad track anvil in the lack of mass directly under the hammer's blows. It will work but not as well as a more solid design. I have also seen some good designs based on a round shaft set on end - a piece of 6" round, 24" long will weigh close to 200 lbs.

I think a big block of steel would make a better anvil but if you are stuck with RR track, then Jr's comments are spot on. However, water will do a better job quenching as the mass is too great to harden properly in oil. I have repaired and rehardened several conventional anvils and can affirm that a large amount of water in a cascading column is needed to remove the heat.

I have dirt floors but my last shop had a brick floor on sand. I was given several pallets of red bricks so I raked some sand onto the floor until it was level and then laid bricks until I ran out about halfway across the shop. At that point, I staked some timbers up against the last line and swept sand over the top of it all. It was OK to stand on but started sinking in various spots after a year so began looking a little wavy. I still think oil on dirt is good but it may have environmental issues depending on where you reside. I have several gallons of old vegetable oil that I may try on a few dusty spots - trouble is, the dogs may start trying to eat the dirt... :mrgreen:

The steel actually burns - and yes, a torch does the same thing. I am no chemist but have been told that the carbon content has a lot to do with the propensity to burn so pure iron will be harder to ignite than a piece of 1090. This theory seems to hold true because wrought iron will withstand higher temps than spring steel or other high carbon material. A plasma arc vaporizes any conductive metal and blows it away. An oxyacet torch burns steel but won't work on metals that can't ignite.

...or start with what we used to call a "grubbing hoe". Might be the same thing Thomas is referring to but the ones I've owned had an ax on one side and a mattock on the other. Seems it would be pretty easy to make an adze from one of these.

If the other side is in good shape, you may want to simply grind the chipped area into a very large smooth radius to use as a bottom fuller for heavy drawing. Welding is OK but typically a lot more work and the results are not always as predictable. Another option is just leave it alone and use the rest of the anvil. There are plenty of areas left for forging.

One of Guy Lautard's "Home Shop Machinist" books has a whole chapter on gasoline torches. How to build, what features are important, etc. Might be worth buying a second-hand copy on Amazon and reading it - lots of other good "metal stuff" in that volume...

I made a portable set-up for craft shows and demos. The forge is a 12" round Centaur pot mounted in one end of a 55 gal drum. The other end is cut open to let ashes fall on the ground. There are also two cutouts in the barrel - one for the air duct and the other to reach the clinker breaker handle. I reused the piece of sheet metal cut from the end of the drum by cutting it down the middle then mounting a piece on either side of the pot so I can pile coal up against them. They also act as a small wind break so the smoke doesn't blow willy-nilly in the breeze. People want to see coal or charcoal - they think gas is too "modern". Post vise is mounted to another 55 gal drum. I fill the drum with water so I have a slack tub plus the vise is anchored. Dump the water when finished and you are good to go. My blower is a manual type (Tiger 300) with a piece of 3" heater duct for an air pipe. It is mounted on three legs and completely portable. For a while, I used a good Champion electric blower but found I could not always find consistent electrical hookups so I switched to the hand blower. Anvil is a good quality, no-name, wrought 100 lb. It can be placed in a separate stand and locked into place. The stand has an angle iron top to fit the anvil, which is welded to a 4x4 piece of box tubing. The other end of the tubing is welded to a 55 lb plate. The stand weighs about 100 lbs so the whole thing is around 200 when assembled. The stand has a tool rack welded to it so I can drop about 10 hardy tools in place and have ready access to them. I will not work where I can't find shade so will either set up under a "pop-up" tent or a tree. It does not matter if it's bright - I just don't like direct sunlight. I ALWAYS rope off where I am working and do not make exceptions to this rule because I don't want people walking up and sticking their nose on top of the work. I once went to a demo at a living history museum where they encouraged people to crowd the smith so they could see him work. One youngster walked up and started tapping a piece of scrap on the horn while I was forging a piece and talking to the crowd. I was not rude but finished the piece and let him wander off, then I went to the truck and got a piece of rope to keep the throng back at a safe distance. Sure enough, the show coordinator came by and started complaining - I stopped him in mid-sentence and said either the rope stayed or I left...end of conversation. I precut everything I plan to demo/make and often do preliminary steps at home, then complete the final assembly in front of the crowd. I find very few people know the difference plus I don't try to hide it - I simply say that I did such and such at the home shop and explain as I go. I demo for both the general public and for blacksmiths so I tailor the demo for the audience. I put all of my tools in two or three 5 gallon plastic buckets and work from there. Don't try to take your entire home shop - plan your demo and only take what is needed. I can fit everything in my short-bed truck and also can dolly everything to the work site. I thought long and hard about having to move it all by myself and designed it with that goal in mind. It does not have to be very scientific if you plan to only do it once or twice but you really should put some thought into it if you plan to make demonstrations a regular habit.

How many of these do you make for Volvo? Is it for research purposes or in production quantities?

Leah, A rheostat reduces voltage thru some sort of resistance circuitry. A straight AC motor without brushes needs to have close to full voltage to start. In other words, a 110v AC shaded pole motor with little basic load may start down to about 75 volts or thereabouts. I'm not talking about capacitor start motors or others under load - just direct drive fans like we would use on a forge. However, they will eventually reach a stall point where they won't turn and in reality, a squirrel cage AC motor is essentially either on or off, because the little blades on the blower cage don't catch much air when spinning slowly so you are back to my earlier comments in this thread about pushing oxygen thru a mass of fuel. The advice you've heard to begin at full speed is so the fan will start, then you can turn it down to a certain degree, but the only thing you can have almost infinite control with is an AC/DC motor that has brushes. Most of the old electric blacksmith blowers are this latter type and will continue to rotate with very low voltage so there is always a breath of air going. I believe it is best to install your electric blower with an on/off switch then put your air gate before the firepot. Turn the fan on full speed and control the air by choking the path (or the inlet - either works). In this way, you get the maximum amount of pressure the fan can deliver, but the volume is controlled so the fire doesn't get out of control.

Ed brings up a couple of good points I neglected to mention. Stainless flex tubing is great but aluminum heater duct as found at Lowe's or Home Depot also works well. One downfall is that moisture which might accumulate in the bottom of any bends can combine with coal dust and eat a hole in the Al in short notice. Another problem is that this type of material is very soft and easy to poke a hole thru. Other than that, it conducts air just fine. More good advice is Ed's note on speed control. It is far better with an electric blower to regulate with a damper or air dump than to mess with the speed. I learned this lesson when I was able to acquire a factory Buffalo forge with electric blower and rheostat. This forge (which I still use daily) came from an old Air Force surplus sale and had seen little or no use. I was fortunate to be able to see how the factory put one together - all the way from the stock rests to the half-hood. It was readily apparent that even on the lowest setting, the fan would outmuscle the fire in seconds. I burned up a lot of material until it finally dawned on me to leave the fan on and just adjust the air gate. The rheostat had specific "clicks" so I believe it was the factory's intent to operate in this fashion. For my single dedicated forge, I never use anything above the lowest speed setting but it is clear the blower will run multiple forges, so I'd bet lunch that Buffalo made it so the shop foreman could turn it on in the morning and have the workers control their fires as required.

Some years ago, my youngest son wanted a Roman style short sword so I helped him make one from mild steel. It came out looking fine but bent and dinged badly when he hit anything hard - although it cut weeds and cactus until he finally got tired of it and went on to other toys...

From the standpoint of blower design, I have some real specific preferences on this subject. Moving air has both pressure and velocity (cfm). For example, an air compressor will easily build enough pressure to blow fuel out of a firepot but the amount of oxygen moving thru the fire will be neglible. Try hooking up a compressor to a firepot - even at a low regulated pressure, you'll be hard pressed to get a good fire. Squirrel cage blowers have a lot of small blades and are designed primarily to move air thru HVAC systems, so the CFM ratings are high but the static pressures are low. The reason for this is that there are few restrictions in properly made ductwork, but you do want a lot of air velocity so the hot/cold air makes it out of the vents and into the dwelling. On the other hand, a traditional mechanical blower is made in a centrifugal design, which means it has a few large paddle blades - usually six or eight. This type of blower is intended to push air with some pressure but at a lower overall CFM rating. A blacksmith's coal/coke/charcoal fire requires enough oxygen to get hot but it also needs enough pressure to push the air thru the fire. This is why a bellows or mechanical blower works better than an electric squirrel cage - the former both deliver sufficient CFM to provide plenty of oxygen and enough pressure to make it thru a mass of burning fuel. This is really noticeable when forge welding, as only a breath of air is required to reach final temperature but it has to make it all the way. The squirrel cage fan will make a nice roaring fire but you will experience more oxidation and hollow fires because there is just too much air moving thru the fire. If you try to choke the fan, the static pressure begins to diminish to a point that only the bottom of the fire gets hot. To compound the problem, this problem gets worse when a clinker or other obstruction forms. When I do demos for the public, I use a "Tiger 300", which is a good sized mechanical hand blower. I don't know the manufacturer's name but it's a Champion clone - easy to work all day long with a decent fire and minimal physical effort. IMHO, there is a reason that experienced smiths still prefer to use a great bellows or old hand blower and that is because they have no peer for the purpose of supplying air to a blacksmith's fire.

I prefer a square faced hammer with heavily radiused edges so if necessary, I can use any of the four edges to draw. Several of my hammer handles are also faceted in a octagonal cross section so I can feel the head orientation without looking. I leave a bulge on the end of the handle so it doesn't fly out of my hand and sand the handles to about 400 grit with several "whisker" sandings to get them quite smooth. I use Birchwood Casey's Tru-oil for a final finish and find it holds up quite well - much like a gun stock. I hold the handle very loosely and allow it to slide back and forth as I work. Knock on wood, I have no arm or elbow problems after 25 years of steady activity. However, the whole hammer thing is very personal and I feel a beginner should experiment until he/she finds whatever is comfortable. I started with a 2-1/2 lb head, went to a 3, then a 4 and back down to about 2-1/4 lbs now. It is better to strike the right spots with precision and at will, with a lighter hammer, than to get carried away with ego and blow out your arm because "only real blacksmiths use a 4 pounder"...

"Off-Center" tongs by Grant Sarver are some of my very favorites. Made by a 'smith for 'smiths - they are light and easily handled while retaining a lot of strength.