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I Forge Iron


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Everything posted by Buzzkill

  1. I've been on lifting restrictions due to surgery recovery the last couple months, so I decided to rebuild my forge and I worked on a new NARB design as well. The last NARB I made used a portion of an IFB with lots of 1/8" holes drilled in it. It worked well for a while, but lately I was having to turn the pressure up significantly to keep it from burning back into the plenum. I dislike casting burners, so I'm always trying to think of designs that will function well and allow me to replace the burner head without casting a new one. Here's what I came up with (with some consultation with Frosty in PMs): I used a piece of fiber board rated for 2600 degrees F for an "insert" into a cast refractory "box" that is cast directly onto a steel plenum made from folding sheet metal (around 1/16" thick) into a box with an open end. The refractory box has a lip about 1/8" placed so that the fiber board insert rests on it and is flush with the edge of the refractory box on the flame side. I didn't start taking pictures until after I had already cast the refractory box onto the plenum and tested a fiber board insert or two. I'll share what pictures I have though. This pic shows the burner after testing and another insert sitting on the burner face for reference. That one had 75 "nozzlettes" with inner diameter of 2 mm. It wasn't enough throughput, so I moved to bigger holes. I ended up using stainless steel sleeves in the holes in hopes that this will prevent/reduce degradation of the fiber board in use. I had wanted to try this before with cast burner heads, but was concerned that the difference in thermal expansion would cause problems. Fiber board has enough "give" to it that this should not be a problem. The sleeves I used have this description "T316 Stainless Steel Protective Protector Sleeves for 1/8" 5/32" 3/16" Deck Cable Railing Kit." Here's what an insert looks like from the plenum side after all the sleeves have been installed and cemented in place: This gives me 44 holes on slightly larger than 2" x 6" fiber board insert. The ID of these sleeves is 13/64", and the length of them is such that they don't quite reach the opposite side of the fiber board I used on the flame side - which is what I wanted. The fiber board was listed as .8 inches thick btw. The next pic shows the burner after cementing the fiber board in place, test firing, and then coating the flame face with a kiln wash that is supposed to be good up to 3000 degrees F. Here's a pic of the cement I used to keep the sleeves in place and to glue the fiber board to the cast refractory box. It's only rated for 2000 degrees F, so I don't know how it will hold up long term. The next pic shows the burner functioning with no visible pressure showing on the gauge, so less than 1 psi. This is what it looks like from the outside of the forge. I tried a number of different combinations of 1/2" and 3/4" T burner modifications. In the end I believe my best results were with a standard 3/4" T burner setup using a .030 mig tip that was trimmed back a little over halfway compared to the opening when viewing from the side. That took me from cold forge to "forging orange" in about 10 minutes. It took me a total of 20 to 25 minutes to reach what I'll call "butter stick yellow" heat where I'm comfortable forge welding high carbon steel. After running at forge welding heat for 20 minutes or so I turned it back down to less than 1 psi without it burning back into the plenum. There are some issues though. First off, I can't keep it lit outside the forge even with very low pressure. It blows the flames off the burner face. Inside the forge it stays lit, but there is some flame lift away from the burner face until the forge gets hot. If I did my calculations right this burner has about 80% of the throughput capacity of a 19 crayon hole burner. However, with the shorter nozzlettes and the different material the friction is certainly different. I'm not educated/smart enough to try to figure out a direct comparison between the two. Secondly, in my forge at least, this design suffered from what I'll call "harmonic howling." This is a sound similar to, but more intense than, blowing across the top of an empty glass bottle. It is affected by a combination of back pressure and temperature - and maybe other things as well. Once it starts it can be stopped by covering the air intakes to reduce the flow or by turning the regulator down. Over time as the forge heats up greater pressure can be used without the phenomenon occurring, but it really can be annoying when it's happening. I did a little online research and found that model steam engine propane burners sometimes have the same issue, for whatever that's worth. I've only had this in use for a handful of hours, so I have no clue as to the longevity. My goal was to create something that functions well and that I could quickly refurbish without having to do more casting. Hopefully when/if it fails I can just remove the old fiber board insert, cement in another one and get back to business. However, it won't surprise me too much if my cast refractory box fails before or when the fiber board does. I used sifted Kastolite 30 for the box because that's what I had on hand, but I believe there are better options out there. I didn't need to make the steel portion of the plenum quite so long. That could have been about 1.5 inches shorter, and I don't think it would have negatively affected anything. Since the plenum is so large I get a pretty good pop when I shut the gas off and the FAM inside the plenum ignites. I still need to get the forge interior coated with Plistex, but it is functional as it is and so far the burner seems to be performing in line with my expectations.
  2. I know there is a pic in the instructions that shows this, but I'm not sure it's recommended. My experience with T burners is anything that impedes or changes the direction of the fuel air mixture flow before it enters the forge tends to negatively affect the burner performance.
  3. I have used a single port T burner in a forge and then used the same T burner attached to a ribbon burner in the same forge afterwards. Of course I had to cut a hole in the forge to accommodate the ribbon burner, so that resulted in a change to the forge interior (and the ribbon burner was top-mounted while the single port was side-mounted), but otherwise it's apples to apples. I didn't take temperatures, use a stopwatch, or weigh propane tanks. What I can tell you is that I could achieve the same heat (by my eye) using lower pressure in the same T burner set up when using the ribbon burner. That is an indication of requiring less fuel to accomplish the same thing - i.e. greater efficiency. I'm not out to prove or disprove anything to anyone. I'm sharing my personal experience/observations. For me the ribbon burner overall wins hands down. The factors for me are 1) it's MUCH quieter than a single port burner, 2) it provides a MUCH more even heat distribution within the forge, and 3) It appears to require slightly less fuel than the same single port burner in the same forge. Someone may want to take the time and trouble to collect and compile all the necessary data to prove things in a quantifiable way. I'd rather spend my time heating and beating on steel.
  4. Personally I'd just do stock removal with that size stock. You just don't have enough excess thickness to move the metal around much and you will lose some material due to scale and grinding out errant hammer marks. I like at least 1/4" thick stock to start with. Others may have their own preferences. Looks like TP already beat me to it.
  5. This is an oversimplification, but think of the difference of a single water hose with a specified amount of pressure shooting into a mostly enclosed area. Now think of the same supply hose having the stream divided into smaller streams shooting into the same mostly enclosed space. Which one do you think will result in more water staying in the space for more time? We're not talking about a difference of twice as long or anything like that. Just slightly longer. It is more complicated than that in reality. Typically the total area of all the individual holes (or nozzlettes as we sometimes call them) in a ribbon burner is greater than the area of the mixing tube that feeds it. There is friction between the fuel air mixture and the walls of whatever it passes through. The surface area causing friction in a ribbon burner is not inconsequential. The result is that complete combustion can occur in a shorter distance and with slower flames in a ribbon burner compared to a single port burner. My personal observation is that a ribbon burner is slightly more efficient and definitely provides more even heating within a forge compared to a single port burner. Another major issue for me is that ribbon burners tend to be significantly quieter than single port burners. Even if there was not any gain in efficiency, that factor alone would be enough for me.
  6. I also built a tire hammer without any plans, so specific questions about that design I can't help with. However, for the anvil I acquired quite a bit of 3/4" thick by 6 inch wide steel. I'm only part way through the anvil creation, but when done I'll have 8 pieces with full perimeter welds to give me a 6x6" anvil 30 inches tall. I was fortunate enough to obtain this steel for a little over scrap price from an acquaintance who does a lot of junking and knows to look for certain things for me. I would not have wanted to purchase the steel new right now.
  7. You'll need to do some type of annealing to soften up the O1 core. I suggest heating it up until it's barely glowing but still magnetic and then letting it cool slowly. This is sometimes referred to as a "sub-critical annealing" process. It won't be as machinable as the annealing process on an O1 spec sheet would provide, but it should allow you to do your file work and/or drilling. As for carbon migration, you'd probably have to fold and forge weld 3 or more times before the carbon content is dispersed more or less evenly throughout the billet, but with mild steel being one of the alloys you'd probably end up with a billet unsuitable for keeping a decent edge.
  8. You can still do it in 2 sessions if you turn it one way and cover what gravity will allow then turn the other way and meet in the middle so to speak - or you can do it in 3 separate applications. Either method will work. The surface of the blanket should be quite damp, but not have standing water on it or anything. The bottom line is you don't want the blanket wicking water away from the Kastolite. The water in it is needed for it to cure properly. I mix Kastolite by eye/feel. There is a fairly narrow range of water between too dry and too wet. I usually get it a little too wet intentionally to begin with so that it mixes well and then I sprinkle on a little dry product, mix, and then add more and repeat as needed until I get the consistency I'm looking for. You don't really need the additional bubble alumina on top of the Kastolite, but it shouldn't hurt anything. It might make your heat up time slightly longer is all. If you have a properly sized, built, and tuned burner for the forge it should be a nice change for you. If nothing else you should have a little more space to work with.
  9. Sure, it's always a risk with multiple layers. Keeping the core centered in the billet can be a challenge and takes some practice. Also, if you grind your bevels rather than forging them you are even more likely to remove a lot of the outer layers. In general it's easier to get good forge welds on small surface areas and then draw out the billet rather than trying to forge weld a billet close to your final dimensions. I prefer billets to start out around 1.5 inches wide and 4 inches long personally. The size of the finished product, or the number of layers desired in pattern welded billets, determines how thick it needs to be at the start. Are you doing this technique just for practice, or are you trying for a soft outer shell for toughness purposes?
  10. I'm not sure what the "official" recommendation is, but here's what I do: I set the shell so that I can cover the largest area possible without moving it. Then I apply that largest section in one session. Kastolite starts "firming up" as it sets fairly rapidly. You need to be comfortable that the first part you cast won't fall off when you rearrange the shell for the next section. That can be even less than an hour sometimes. Remember to wet (butter) the rigidized blanket before applying the Kastolite layer. You don't necessarily need to turn it completely upside down. You may be able to turn it halfway one direction, then halfway the other direction so you can apply to the blank spots without gravity pulling the previous section straight down. I usually wait a couple hours or resume the next day. I don't know with absolute certainty, but my impression is that subsequent applications of Kastolite will bond better to previous applications if they are still damp, but solid. As others have mentioned elsewhere, I find I get the best results by "patting" Kastolite with a trowel, putty knife, or even rubber gloved hand. That tends to pack it into place better and pushes the rough edges down past the surface. I do not recommend firing until all the Kastolite has been applied.
  11. You can always double up the high carbon steel in the middle. It's another forge weld seam and another potential failure point, but when properly forge welded, two pieces of the same alloy become one solid piece of that alloy.
  12. There is no one size fits all answer here. The short version is you really want complete combustion to occur before the flames reach the work piece. However, the number and diameter of holes in the burner face will have a big impact on the distance required for complete combustion, as will the pressure of the fuel and air mixture in the burner. Four to six inches should be more than sufficient for most ribbon burners, but yours could be different.
  13. This is probably an over-simplification, but Kastolite has 2 schedules for all practical purposes. The first is the curing stage. This has nothing to do with drying per se. In fact it's best done in high humidity, but will happen faster with the temperatures you listed. However, most of the time if you apply heat you're also reducing the moisture in the area heated, which will make Kastolite weaker. After the curing stage is complete (at least 24 hours, but up to a week) then you can start stage 2. That's when you drive off the excess moisture slowly. You don't want any remaining water to flash to steam, which could cause mini-explosions in the material. Then it's just continuing to raise the heat and duration of heats until you get to operating temperatures. According to the spec sheet for the material it's somewhat weaker in the mid range of its operating temperature than it is after being fired at high heat for a while. Satanite is different. It is a clay based material that does indeed dry out rather than "cure" or "set." That one you paint on in thin layers, dry, repeat until you get the thickness you want.
  14. A couple things: First off O1 can air harden in thin cross sections. I've had this happen a few times. It becomes quite evident when you attempt to drill holes for scale pins and the drill bits just scream at you. Secondly, the rate of thermal expansion/shrinkage for O1 and mild steel are not the same. When doing a san mai technique with mild steel on the outside, you really want that central core to be twice the thickness (or more) compared to one of the jacket layers. The mild steel can literally pull the hardenable steel apart. I've seen it a couple times where the layers welded together fine, but the hardenable steel core cracked right in the middle rather than at the weld seams. So again, the way to reduce the likelihood of that happening is using a thicker core and thinner outer layers. Hope that helps. Gouda luck!
  15. This was just for the 2 places where the half cylinder meets the flat floor. There's no shortage of space for exhaust gases to escape because of the front opening and the rear pass-through.
  16. I found the article and the comment. Here's a portion of the comment: "I can add a little to the Richtig story. As a young boy for a number of years during world war two he was in need of aluminum to make his knives. My dad had quite a few pistons from doing overhaul jobs on cars and tractors and when my Red Ryder wagon got full I would take them to Frank. Many times when I took them there he was tempering blades. In the process he took them off the forge and dipped the blade in a solution in a bucket, I don’t know what the solution was or how long he kept them in it, but after they cooled he would hit the blade on an anvil with one hand and with other he would hit a tuning fork. If the tone was the same the blade went into the good blade bucket, if not it went to the forge later." And here's the article: https://clarksonhistory.wordpress.com/2013/05/06/secrets-of-the-dead-the-richtig-knife/
  17. I read an article about him a few years ago which contained less technical information, but more or less the same story. What was interesting is one of the commenters on the article claimed to have been a child in the town where and when Richtig was making his knives. According to this person one of the things Richtig did was tap each blade against something and listen to the resulting sound. If he didn't like the sound he tossed it in the scrap pile, and if he did like it he would finish the knife. Of course I have no way of knowing if any of that is true, but it is entirely possible that he did have quite inconsistent heat treating but also used sound to weed out those that would not perform well.
  18. What I did where the "dome" meets the floor on my D shaped forge is use a couple strips of fiber blanket which were sprayed with rigidizer to make a gasket of sorts. This makes removal of the top portion easy when needed but also provides a "flame tight" connection between the two slightly irregular surfaces.
  19. This is what makes it tough. The result of infection with the virus ranges from no symptoms at all to death. That's pretty much the maximum range possible. It's like viral Russian roulette. I tested positive and had relatively mild symptoms last December. Others my age in my area have perished from the virus. For me this is no different than any number of other safety related issues. Each person should assess their personal risk based on the information available and protect themselves and those around them accordingly. However, you cannot use logic to help someone out of a position they didn't use logic to get into in the first place.
  20. If you have any kind of grinder (bench, angle, belt, etc) and a reasonably steady hand I'd recommend grinding 3/4 or more of the cutting edge in and then finish with the stones. You'll wear out your arms and your stones removing that much metal that way. If you have no grinder then you may want to try some low grit sandpaper with a backing board and your jig to get the cutting edge close to where you want it to be. And BTW, I agree with your kids. Looks good.
  21. TP - Granted, but the question was really whether a single 1 inch layer of insboard would suffice.
  22. Not sure that helps with his situation. I've only used fiber board on a very limited basis. However, it did seem to me that the insulating properties are impressive. I had a piece glowing on one side with my hand comfortably on the other side from where it was glowing. That was an inch thick piece, so you are probably ok with a single 1 inch piece. If you want extra peace of mind you could add a second layer, but I doubt it's necessary.
  23. I rarely do false edges on the spine, but when I do they are less than half the length of the spine and I grind them after the bevel for the cutting edge. I have no particular reason why. It's just the way I do it and any way that safely gives you the result you want is the right way. Your bevel in the picture above looks pretty darn good to me. I like that you gave yourself a lot of options for changing the bevel angle slightly in your jig. Well done IMHO.
  24. Oh there are some definite benefits. I like it hanging on the wall rather than taking up space next to the furnace and water softener. It's also really quiet. I had my doubts about the claim of 93% efficiency, but the exhaust coming out of the system is barely warmer than ambient and exits the house via PVC pipe. I'm not sorry I did it. I just really didn't know what I was getting into as far as the extra expense and labor goes. If I was building a new house I'd probably spec it out with a tankless water heater to begin with. In the negative column it does take about 15 to 30 seconds longer for hot water to get to the top floor of the house, and of course if the power goes out there is no stored hot water unlike the tank. However, not having to be concerned with 3 people taking a shower before you using all the hot water is a definite benefit.
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