Ramsberg

I found a reference to the supply pressure of air to a side blast forge in Forgecraft, here is a link to the full book scanned by Google: http://books.google.com/books?id=gYJIAAAAMAAJ&printsec=frontcover&dq=forgecraft&hl=en&ei=rt2LTIKKNYOinAeW4_CSCw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCUQ6AEwAA#v=onepage&q&f=false It says that the minumim blast pressure for an 8" deep fuel bed is 3 ounces per square inch, that equals 5 1/5" of water column. It also says that two or three pounds per sq in is a bit too much, as it will oxidize the fuel. It has been a while but I recall that air passes through charcoal much easier then coal, deeper beds for heating larger stock require more air pressure to get it through then shallow beds. I have seen guys pump the top bellows full and keep on pumping to get the fire really going, never went that far myself, that must have been a pretty good pressure developed! Back to Rockstars bellows, 4' long by 2' wide with a taper, an estimate is that it would have 3 1/2 to 5 1/2 sq ft of head area, for a 5" water column of air pressure that would be 26 lbs per sq ft or 91 lbs to 143 lbs of force on the head. A thick head board with the weight near the big end giving i leverage would be very close to that. Does anyone reading this have any idea how much force they have on the top head of thier bellows and its area? Caleb Ramsby

Grant, To elaborate upon your analogy, take the head off of that engine and how much pressure is developed? Put the head back on and make a large hole in it, that will produce a little bit of pressure, the smaller the hole the greater the resistance to the air flow so the greater the pressure required to produce said flow. No hole and then the pressure developed is dependent upon the ratio of volumes and the polynomial coefficient of compression for that gas mixture in that engine. Caleb Ramsby

Grant, I believe that I wildly overestimated the amount of fuel consumed per hour. From looking at a few posts on the subject it looks more like 2 - 5 lbs of coal per hour. I must have been studying locomotives a bit too much, they can burn well over 80 lbs per hour per sq ft of grate. Otherwise I stand by what I said. The pressure that the bellows develops is dictated by the resistance to the air flow, the lesser the resistance the lesser the pressure. I don't like to be argumentative, I like to be helpful when I can be. Caleb Ramsby

Hey Tim, Exactly right! This is one reason that I prefer bellows over cenrifugal fans. With a bellows the delivered volume of air is dependent on the rate at which one pumps the bellows, with a fan the delivered volume is dependen on the area of the discharge and the difference between the head pressure created by the fan and the resistance head produced by the delivery passage, discharge coeffecient and fuel stack. I had a pile of ligh fuel "blast off" when I was using a fan. What happened was that I was experimenting with wood pellets(not the best) and when they char they just fall apart and were clogging the bottom blast forges discharge. There was virtually no air being delivered to the fire and I was cranking faster and faster, then all of a sudden the head pressure was enough to dislodge the fuel and the full blast of the air shot out, it must have shot the fuel two feet above the hearth! Scared the crap out of me! HA! After that I trusted fans less and less, bellows are much easier to control in my opinion. As an aside I had more clinker from those wood pellets then I had from good coal! Then there are the sparks that the pellet fuel produced. . . Maybe this belongs in a new thread, but I wonder what the average firing rate of most blacksmiths is. There would be the hourly rate which would be the fuel consumed per hour and the firing rate which would be the fuel consumed per hour of blasting the fire with air. It has been a while since I have had a shop set up, but I seem to remember going through roughly 20 - 40 lbs per hour, depending on the size of the work. Caleb Ramsby Caleb Ramsby

Grant, It gets a lot more complicated when the speed of sound in approached, the density of the medium also changes the speed of sound, so the more the air is compressed the higher the speed of sound is. When it exits and expands into the atmosphere a bunch of wild stuff happens. The speed of sound in the atmosphere(sea level) is roughly 1,085 fps, in theory it would require just over 9 3/4 psi to produce a flow approaching Mach 1, in reality things are a bit different. That formula is for lower velocities. A blow off tool using compressed air is well above supersonic, that is one of the reasons that it is so loud, that is also why whips crack. One psi for 236 mph doesn't sound like much, but if you put your head into an air at that speed(mine is roughly 70 sq in) if the coefficient of drag was 1 then that would be 70 lbs trying to rip my head off! The force on a 24" by 24" window pane would be 576 lbs! Caleb Ramsby

It is the volume of flow and the restriction to said flow that produces a pressure differential, either a negative pressure trying to fill a container or a positive pressure trying to empty it. I made two references to the valve and pressure, one being its restrictive nature producing a negative pressure inside the first chamber, the second being the delivery pressure of the air acting on the valve face producing a load on said valve. The area of the bellows doesn't effect the pressure per square inch, but it does effect the total weight required produce the delivery pressure through the nozzle. Lets say that you are burning 50 lbs of coal an hour with the forge and it is being fired 1/2 of the time, that would be a firing rate of 100 lbs per hour requiring at least 210 CFM of air. Delivered through a 2 sq in nozzle that would be 252 fps air velocity, the head pressure for that velocity would be 14.5" of water head, adding in the loses it would be at least 17" and closer to 20" or more. That is the pressure per square inch that would be required inside the delivery chamber of the bellows. The bottom feeding chamber would have to be a bit greater to force the air past the middle plate valve and against the pressure in the top chamber. The quantity of coal consumed in this example is rather high and the nozzle size is a bit small too. So if you were burning half of the coal in the prior example with the same nozzle area then you would require at a minimum 105 CFM of air which would give a velocity of 126 fps, which would require a head pressure of 3.63" of water, the flow loses would also be a bit less so an estimate would be around 5" - 7" of head pressure in the bellows. For the 8" by 8" valve described above that would be 11 3/5 lbs to 16 1/4 lbs on the valve to seal it. This is probably what one would normally be running at. But if you built a really deep fire to heat a really big chunk of steel the head pressure must be really great to supply enough air for the big fire. Really neat stuff, I love it! Caleb Ramsby

I have to ask. Have you ever tried the stacks without the turbines? Those are some very straight, large in diameter and tall stacks, perfect for a really good chimney effect with few losses. I am just curious to know if you ever used just the stacks without the turbines and if so how big was the difference. Thanks for indulging my inquisition. Caleb Ramsby

Here is a simple test, your new valve is 8" square so that is 64 sq in. When one is really pumping one pound per sq in of pressure developed inside the bellows isn't out of the question, so that would be 64 lbs. If you were to take place 64 lbs on top of the valve would it hold its shape and stay sealed? Wood is by far the best material to use for a valve(to me at least), it readily seals against a felt strip and even if just 3/8" thick is very stiff compared to a sheet of steel of the same weight. Ironically you may have made the valve to big. There are a few reasons that multiple valves are used, one is that they spead the flow of air across the carcas of the bellows, another is that they allow comparatively smaller valves so the valves can be smaller and lighter. For two holes to have a total of 64 sq in they would need to be roughly 5 5/8" square, for three holes 4 5/8" square. I would use the vinal as a hinge for a light plywood valve. A fun fact, for an open exit one pound of air pressure will produce a velocity of 236 mph. V = 66 * sqrt(H) H = head in inchs of water : divide by 27.6 to get lb V = feet per second : divide by 1.46 to get mph I have always liked small bags of sand or rocks as weights for the top of the bellows, that way you can hand them at hand and they won't disapear on the other side of the shop. Also they will give just the right flow for the work and fuel at hand. As a side note you shouldn't need any weight on the bottom plank of the bellows, it should drop rapidly from its own weight. What is happening is that the small inlet holes are producing a significant vacuum inside the bottom part of the bellows and this tends to give them an artificial lift, you probably noticed that when you put a bunch of weight on the bottom board the sides of the bellows sucked in really good, that is why, the vacuum. Hope that this helps some. Caleb Ramsby

I remember reading somewhere that a tuyere constructed of copper without water cooling is supposed to greatly outlast one consructed of steel or cast iron. It makes sense to me, copper has a rate of conduction around 10 times that of steel(depending on the steel) and reflects almost all of the radiant heat, where as the steel absorbs it, especially if it is oxidized. Thinking about it I believe that the heat with a copper tuyere is conducted down its length back towards the air entry, which part is cooled by the air flowing in and a natural convection from the outside air. Anyone out there ever seen a copper tuyere? Because of the cost of copper I have a feeling that they are very rare. Having said that I have only used a bottom blast forge, but have always been fond of the idea of a side blast. Has anyone ever seen a shop with both a side and bottom blast in the same shop? It would be ineresting to try them truly back to back. Caleb Ramsby

One old farmers trick was to go into the spring house and hold the wrists in the running water. I have found that to work miracles when working in hot weather! A source of cold running water is required, just hold both wrists under some running cold water every half hour or hour, just for a few minutes. I prefer drinking water that is almost warm, it absorbs more slowly and doesn't shock the system like very cold water does. I am hypoglycemic so those "sports" drink loaded with corn syrup and sugar are bad news. For recovery and preloading of salts and such at night I use 1/2 teaspoon of salt and baking soda mixed very well into a quart water, it mixes better with slightly warm water. Preloading with water the night before, as well as some of the "rehydration" drink and keeping the core temp down by cooling the wrists has kept me from ever getting heat stroke. Caleb Ramsby

Hey Bad Creek, That is a nice hook, better then my first one! No split ends for to begin with. . . Seeing as one of the most significant aspects of blacksmithing is being able to make tools, how about trying some small clay modeling tools, or a bit more complex but doable light and collapsable easel? Northern Illinois, Caleb Ramsby

Hey JimBob, That sounds like a sure fire plan! I would not suggest making it in multiple pieces like I did, it only caused problems instead of providing solutions like I had hoped it would. A piece of 3/4" or larger square stock should be plenty for your purpose. Seeing as how you already made a long steel handle for the shovel, my advice here is most likely mute. Good luck and happy roasting! Caleb Ramsby

You know I can't help but think that there is a market for massive bon fire hook/pokers. As of yet I have never seen one the size that I built the afore mentioned poker. My only real concern with it was that, well it was made for use with a very large bon fire where people are not exactly what one would call carefull or in complete control of themselves. I never heard about anything going wrong with the one that I made, but it was always a concern of mine. It being able to be quickly broken down, yet still very solid when assembled was an issue. The bolts were strong and solid enough, but caused issues with assembly and dissasembly, lot of options there I supose. Caleb Ramsby

Nice poker John, keep at it! An early semi-failure of mine was a rather massive bon fire poker/hook. At the time my buddy was throwing a lot of bon fires so I decided to make one for the purpose. It was a bit over ten feet long and I made the hook end from 1 1/2" round stock. With the hook radii around 12"(this was many years ago so the sizes are from memory). The middle section was made from two four foot sections of black pipe, with flattened ends and two holes per end per pipe. The two pipes stradled flattened sections of the hook and handle ends where I had made two holes in each. The idea was to be able to bolt it together and take it apart for ease of moving. It wouldn't fit flat in the bed of a regular truck! I had to prop it up on the gate. The hadle was also made from 1 1/2" or so round stock, with the center of it squared and given a twist(not so easy!), with the aft end tapered down so that I could hang cast iron window weights on it. Those were to counter balance the hook end. It must have weighed over 50 lbs when completely assembeled! Although with the counter weights it was balanced at the handle end, without them one had to hold it in the center, thusly negating the length advantage it had. Eventually it got lost in a field after a bon fire, it must still be out there somewhere, I can't imagine anything destroying it! This might seem really big, but for marine or stationary hand fired coal or wood boilers they would use pokers, slicers and rakes that were easily nine feet long, some even longer, around twelve feet. This was to keep the guy away from the fire and still be able to reach the end of the furnace. They usually had a rounded handle on the end and they would rest it on the bottem of the furnace door frame and slide it back and forth when in use. Those were one piece deals and must have required a helper to forge, or a support of some sort. Caleb Ramsby

Hey Frosty, That was about 8 years ago, when I had first started. Believe me I know better now! I have often wondered why it didn't shatter in my hand when I was forging the other end! Now that could have cut my wrist in the worst of ways. . . Caleb Ramsby

This may not fit the catagory exactly but when I was frist starting out I was making a floor scraper for my brother. He was removing ot that is trying to remove, some glued on tile in his basement. Well, I had a nice thin leaf spring from a car and decided to use this, in a sort of scraper shape, with an attached metal tube handle. Well, after straightening it out hot and forging the curve that I wanted into the scraper end, I took it to the vice to bend it slightly while cold, to get the exact angle I was looking for. Clamped it into the vice, hit it with my hammer, just a tap and I heard the sound of shattering glass! The piece was now in 30 pieces on the floor, very fortunatly none of it was IN me! I had made a BIG mistake and while changing ends at the forge, I had quenched one end at a yellow heat, not thinking about the spring steel and the implications. Then I had forgotten about it later on and didn't anneal that end. I must say that it was as close to an explosion of metal that I have ever had, some pieces were behing me, all around actually. It was rather interesting actually, the steel had the same fracture lines as plate glass. Caleb Ramsby

Hi Junker, Now your on the right track! It is VERY easy to get into the, "Swing a big hammer" thing, especially when one is young and first starting. It "feels" like your getting a lot more done, but in the long run you usually are not and as I pointed out before most likely causing "invisible" damage! A few more points, some that I wish I had heard and followed when I was starting out. 1: Pay attention to how long it takes you to make a series of pieces. It is very good practice to work with 1/2" square stock and make fire pokers or such with it. One way to keep an eye on your progress is to make a group of items, such as fire pokers. All in one forging session, say three pokers in a row, doing the poker ends of them all first, then the handles of them and finally the center, puting in a twist or such. Note the time when you begin and end each group section, such as the time when you start the poker ends and when you end them. Also note the number of heats it takes per operation. Write all of this down and keep a running record. This may seem like a bother, but it only takes a few seconds and can be very enlightening. This will allow you too see your progress, especially your fatigue if you are able to work a whole day at the forge. Such as, make a whole bunch of the same thing all day, in sets of three or more. Then compare how long it took you to finish your first sets and last sets. If there is a major difference between how long it takes for the first and last sets then you are probably still using a hammer that is too heavy! 2: It is very difficult to acquire an effecient and healthy swing, especially when working alone. One option is to video tape yourself hammering and study the body motion before, during and after a swing. It should be fluid and not herky-jerky. The imagination plays a major role in all of this. Imagine that the hammer head is made of a bouncy rubber and not a hard steel. This is what it should respond like when hammering. It is simular to bouncing a basketball. One does not force down the ball with their might, they flick it down with a loose wrist. Try pushing a basketball down torwads the ground without flicking your wrist, it will still go there, but you will have a lack of control, it will not move as fast and you will very quickly get tired! Just prior to the strike you should almost let go of the hammer handle and give a quick flick of the wrist. Nothing drastic, but it's effect can be massive on the accuracy and power of the blow. Not to mention the rebound energy that is achieved from this loose grip, which tends to propell the hammer back over your head! It is also simular in a way to striking a drum. If you have ever struck one you might have noticed that there is a substantial rebound from the drum head, which would be deadened if you were to try and push the drum stick through the head! Well, I hope that this helps some and I have not been too confusing of long winded! Caleb Ramsby

Junker, A grave word of warning! When one is young, such as you are, ones muscles are VERY strong, however ones tenons are NOT and require a much more substantial period of time to develop then the muscles. Thusly even if the 8 lb or 4 lb hammer "feels" light to your muscles, it doesn't feel light to your tenons! You won't notice the damage you do to your tenons now for another 10 years or so, however tenon damage is generally not capable of being repaired. If you over do it now, at twice your age(just 32) your tenons could be damaged to the extent of an average 64 year old. I know that you were just asking about the hammer shape, but I have known fellows who used a 4 lb or more hammer when your age and then in their 30's began to experience devestating pain from torn and damages tenons. The only thing that could be done for them was to take pain pills daily. A 2 lb hammer with a proper and fast swing will move more metal per hour then a 4 lb hammer with a bad and slow swing! That 2 1/2 lb ball peen hammer is the one that you should be using. Personally I don't care for fiberglass handles and would replace it with a wooden one, but that is just me. From what you have said it sounds like you are trying to punch the iron with the hammer, this is very ineffective. Work on your swing and try to make it a snapy, very loose and smooth swing, even when working 3/4" or 1" stock I find a 2 1/2 to 3 lb hammer to be plenty heavy. When punching or drifting a heavier hammer with a shorter handle is very usefull, beyond that not so much. I did not intend to make this out to be a lesson or such, I just don't want to see a buding blacksmith cause irreversible damage to their body when a good warning could stop it from happening. Caleb Ramsby

I read somewhere, can't remember which version of the press it was in(news paper etc.), that after the banning of firearms in a general capacity in England that the rate of violent crime in concert with a robery actually increased. I tend to believe this! The bad guys could still get guns, but the black market price went up, so a lot of the "low level" crooks(see tweekers etc) had to do with what they could get. There were and I am sure still are many reports of persons holding up a store with a broken off and sharpened broom handle! Now imagine being the crook for a second, if you have a GUN pointing at the clerk then you have a magic sort of power. That is the instant and intense fear produced by someone pointing a gun in your face with ill intent! Now imagine holding a sharpened stick to the clerk! Not too empowering to say the least. This has a sort of ripple effect, the clerk looking down at the sharpened stick thinks, "Not today buddy!", then while trying to stop the crook becomes impaled via the crooks pointy, laughable looking but still VERY deadly stick! I have been robbed at gun point, it is not exactly fun. However I never really felt threatened, not in a sense of, "He is going to kill me!". I have also had someone TRY to rod me bare handed. That was a bit more disturbing actually, seeing as his buddy was waiting a few paces off. I managed to convince him without violence not to attempt to rob me, at which point he tried to convince me to help him rob other people. Oddly I envisioned the latter experience going sour much more quickly then the former, there was a MUCH greater intensity in the latter(no gun, just fists and mabey some hidden knives) then in the gun in face incident. One thing that really disturbs me is that when a program is presented, such as gun baning, the results of that very thing in other countrys is not mentioned! It is always proposed as if it were the first such idea in history! I can not remember the exact quote, but Hitler said something to the effect that he would not have been able to propel himself into power, while spouting his manifesto left and right, had the people not been so ignorant as a whole. With all of the "information" out there now, one would be led, and generally is led to believe that the general population has a vast knowledge of all political going ons. I have not found this to be the case and personally know that I don't pay nearly enough attention to which new laws are being placed into effect without proper notification of the public or voting of the public for that matter. They installed "public security observation" cameras in near Chicago for the lessening of police presence and to "fight" the crime. What actually occured after their installment was that the crime rate increased in all of the locations that they were placed! I don't know if this is a physcological response of doing what is expected of you. That is, they place cameras in front of your apartment complex "expecting" you to commit a crime. Well, if that is what they expect of the public what do you think you will get!? It might also be from their generally firing police officers to compensate for the pricing of the camera work and observation of said cameras. Then they installed the cameras here in Rockford and the same thing happened. The crime went UP in the places where they put them. Caleb Ramsby

Leland, Thanks for the reply. It sounds like a two-fer, that is it would keep the handle treated and keep the head from loosening! Great stuff. Caleb Rasmby

Hey Leland, Thank you for sharing! I had read that very article a few years back and have always wondered how well it really worked. Well, now I know! Did you use a wedge of any sort in the head, or just the oil pocket? Caleb Ramsby

Now thats a great picture! I wonder what is with the wrap on the kids hand, second from the right, on his holding hand. Steam heat, I really like the giant sky light! Odd, where are all of the racks and racks of tools? Not to mention all of the projects, look to be shoved in the back right, by the stairs. Those lights are very fascinating! Can anyone place them? They apear to be sparky lights, but have a gas light housing above them, curious. Caleb Ramsby Caleb Ramsby

Say, don't know if this is a good or bad idea, but you seem to be able to split well, that re-entry handle looks great, what about starting with a bit larger stock, split a long section at the handle end, then rounding it with a drift etc. Then, heating it up real nice and placing a cold ball bearing in it? I forsee an enormous amount of issues with getting this to work right, but it would be rather unique to say the least. Caleb Ramsby

When in high school and experimenting with weight lifting I came up with a three point saftey system. That is: 1: The bones act as ancors and the frame to suport the body. The bones are the most important and grow the slowest in response to enviroment(activity). 2: The tendons act as a suspension and conection between the bones and muscle. The tendon grows the second slowest and is almost impossible to fully repair(becuase of constant tension/stress) after an injury. 3: The muscles provide the motive force and regenerate the most rapidly. This provides a VERY dangerous scenario. If one does a LOT of heavy lifting, especially in absence of warming up, cooling off and stretching, the muscles will grow very rapidly and the tendons and bones(connective points between bones and tendons) will not be capable of keeping up. This is what causes a rupture of the connective tissue(or at least one factor) between the muscle and bone. The safest thing to de when working the same muscle group in the same motion is to STOP and stretch slowly and carefully when one loses strength and control in those muscle groups. Especially the minor muscle groups! Every blacksmith should spend at least 20 minutes before and after forging sessions stretching and warming up, slow stretchs NOT jerky ones, they generally cause more damage then they are worth. If you have been in the military please attempt to forget that training systems and stretching systems that you were taught, these are often very bad(although not always), I know too many guys who had their back ruined(as young men) by the bad stretching and excercising systems they were taught there. Especially the standard sit up, just about the worst thing you can do for your back. Frosty hit it on the head with having smooth and flowing motions! That is critical. One of the biggest dangers that blacksmiths face is starting out too heavy or working through fatigue and a loss of control! Especailly when young, the damage incured to the tendons is often ireversible and does not show it self until 10 to 15 years later. So, if your arm becomes fatigued and you begin to loose control, STOP, stretch, rest, let it recover, drink plenty of fluids, then when full strength is back, start again, preferably with a lighter hammer. When I first got into blacksmithing I had 16" arms and could easily swing a 10 lb sledge with one hand, BUT I started with a 2 lb hammer and stayed at that weight for a long time, eventually going to a 3 lb hammer. I knew that although my arm and back muscles were capable of swinging that 10 lb hammer for a long time, my TENDONS were NOT!!! capable of sustaining that stress for an extended period of time! Caleb Ramsby

On my second forge I used 1/8" steel for the firepot, it was used and left outside all year round(rained and snowed on etc.) for two years and lasted that time. I doubt that many will agree with me, but it doesn't really matter all that much how long the firepot lasts, or how deep or shallow it is. Once you have made one, I believe that you will discover just how easy it is, you can also chisel out the hole, I used hole about 2 1/2" square, which was the bottem of the upside down pyramid type firepot, then a square thick wall tube for air delivery welded on, with 1/4" round stock welded together as a grate, it worked OK. You can make the firepot shallower with clay or deeper with bricks stacked up around it, or a sheet metal wall etc. Thicker is however almost always better for a firepot, the 1/8" would glow bright red to shallow yellow in heavy use, but I made it from scrap laying around and it only took about 2 hours or so to build. Your 1/4" should last a few years at least, you'll be ok, when it does burn out(if it ever does) you will have so much more experience that it won't seem like a big deal at all to make another one, this time with the knowledge of what you liked of disliked about the size and configuration that you used. Caleb Ramsby