timgunn1962

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About timgunn1962

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  • Birthday 03/15/1962

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    Lancashire, England
  1. Red hot lead

    Are they painted/laquered? If they are 150 lb-class fittings, it may be a steam temperature rating: saturated steam at 366 degF will have a pressure of 150 psig.
  2. another newbie

    As I'm sure you are coming to expect by now, things are not as simple as they seemed back when you knew absolutely nothing. The blue flame outside the forge is, as you say, partially-burned fuel (more-or-less) finishing its burn as it encounter the additional Oxygen it needs. However, the "to no good purpose" is very wrong. Viewed solely from the standpoint of heat release, it does indeed serve no purpose. However, as smiths, we are not concerned solely with heat transfer. There are several other factors which we need to consider. The main one is the forge atmosphere. If the forge atmosphere is Oxidizing, the unburned Oxygen will combine with the steel and we will lose a significant amount of it to scale. We therefore want a reducing atmosphere: one in which there is a substantial concentration of Carbon Monoxide (CO). The CO "wants" to react with Oxygen to form Carbon Dioxide (CO2). It wants to do this so much that it will tend to remove the Oxygen atoms from Iron Oxide, reducing the Iron Oxide to Iron. It is generally true to say that we want to increase the level of CO in the forge to maximize the amount of steel retained. Against this, we need to achieve the forge temperature needed for the job in hand. The forge temperature depends on many things. Most of them are fixed during the design and construction of the forge and so are outside our control once we are actually using the forge. The 2 remaining factors are the flame temperature at which the gas burns and the amount of gas/air mixture being fed to the forge. The maximum flame temperature occurs near to the stoichiometric air:fuel ratio. This is the mixture at which all of the fuel gas burns with all of the Oxygen from the air, leaving no unburned fuel and no unburned Oxygen. in a (purely theoretical) perfectly insulated forge, this would give a flame temperature of around 1980 degC, 3596 degF. If we change the mixture, the flame temperature reduces. It does this either side of the stoichiometric ratio, with the flame temperature reducing as we get further from the stoichiometric ratio. We don't want to worry ourselves unduly over the temperature reduction on the "lean" side (fuel-lean: combustion with excess air) because this would give an Oxidizing atmosphere with the problems that entails and we're not going there. Instead, we want a "rich" mixture (fuel rich: combustion with excess fuel) to retain as much as possible of the workpiece. Unfortunately combustion Chemistry is quite a lot more complex than we'd like and there is not a simple point, just slightly richer than stoichiometric, at which the forge atmosphere stops attacking our steel. Instead, there is a sliding scale over which scaling becomes less pronounced AND over which the flame temperature reduces. We therefore need to find the sweet-spot where the flame temperature is high enough to get the job done, but the atmosphere is also sufficiently reducing to keep the workpiece sufficiently scale-free to get the job done. The sweet-spot can be quite wide and there are lots of other variables that will impact on this. They include the material being worked, the skill and speed of the smith, the nature of the task and many more. We also have control over the amount of gas/air mixture being burned. In Naturally-Aspirated burners, this is varied by adjusting the gas feed pressure, since the air:fuel ratio of a given burner is pretty much constant over a fairly wide range of gas pressures. We cannot get the forge temperature to exceed the theoretical flame temperature for the mixture, however much gas we put in, but at high gas flows, the forge temperature will get closer to the theoretical flame temperature than it will at low flows. If we have a Naturally-Aspirated burner with a choke, the choke provides a means of varying the air:fuel ratio on-the-fly. In most cases, choked burners are initially tuned with the choke fully open and they are treated just like unchoked N.A. burners during the tuning process. In broad terms, the gas jet is adjusted to get the richest mixture that provides a high enough temperature for the hottest task intended. The adjustment may be changing the jet diameter, changing the axial position of the jet, or a combination of the two. Once the hot setting has been established, running at lower temperature can be achieved by reducing the gas pressure. On choked burners, there is also the facility to richen the mixture by closing the choke to get a lower temperature in conjunction with a more reducing atmosphere. For many (most?) smiths, an unchoked NA burner seems to be quite sufficient. When tuned for welding temperature at high pressure, the pressure adjustment alone seems to allow forging temperatures to be achieved simply by reducing pressure. For knifemaking, the added complication of decarburization of the steel (Carbon Dioxide reacting with the Carbon from the steel at its surface to produce Carbon Monoxide) can make a choked burner sufficiently advantageous to justify the additional complexity. A very finely-adjustable choke can even allow operation with a flame temperature down in the Heat-Treating temperature range. This allows relatively long soak times and therefore allows steels like O1 and 52100 to be treated to more-or-less their full potential without an electric HT oven. Personally, I'd see what your current setup will do first. If you then find you need to go hotter, try a smaller jet. A smaller jet will get you closer to the maximum flame temperature. However, it will mean that there is less gas being burned. Whether or not it will get you a higher forge temperature will depend on whether it is the flame temperature or the heat input that is restricting your temperature at present. Looking at the amount of DB your forge has, my guess would be that the flame temperature is what is limiting the temperature, in which case a smaller jet should get things hotter. Note that some of the CO burns to CO2 in the DB, but not all of it. Adjusting the jet size/position to reduce gas consumption and CO production is certainly not a bad thing, but you cannot realistically expect to reach zero CO release and will always need to take safety precautions. Against the benefits of reducing gas consumption and CO production must be weighed the potential costs of running a less reducing forge atmosphere. This may well include increased time and materials for cleaning up more heavily-scaled work. Halving your gas costs in exchange for a doubling of clean-up costs might not be a bargain. Most apparently simple things turn out to be quite complex once you start to understand them.
  3. Forges 101

    It depends a lot on what the black coating is, and where. That may depend on where it came from. If it's just an enamel-type paint on the outside, it'll be fine. If it's an epoxy-tar internal (or internal/external) coating, and you have the means to remove it, I'd be inclined to do so. With 2 layers of 1", 8 lb/cu ft blanket inside and a homebrewed porcelain clay/Zircopax coating, I've not had a problem with leaving the original paint on compressor tanks, though the stick-on logos tend to get smelly and shrivel up. Compressor tanks are not treated inside, so I reasoned that I could just hit the outside with a flapdisk if the paint caused a problem down the line. Getting rid of an internal coating after the forge is built is a whole different ballgame.
  4. Quenching oil

    Presumably Total Acid Number? I'm not aware of it being a major consideration for quenching oils. It's something I've tended to associate with engine oils used with Sulfur- and Halogen- containing fuels.
  5. Easy Forge Burner Build

    Given that the .023" Mig tip is the smallest available, the burn does look pretty rich (reducing). What it looks like out of a forge is fairly meaningless: there are plenty of rich-running burners doing precisely what they need to do (I don't recall this being specified in the video). With the caveat that digital cameras can really mess with color, that looks like a perfectly adequate forging temperature to me. The video on the other thread looks like a good forging temperature, but probably not a good welding temperature {though I could be wrong). If the forge does what it is intended to do, no changes are needed. There is a lot of Dragons Breath in the video, so if needed there should be scope for increasing the flame temperature with more air relative to the gas. A smaller gas jet would increase air, relative to gas, but is effectively ruled out by smaller mig tips being unavailable. The burner looks very much like a Frosty Tee with some, probably unhelpful, changes. It's not clear why the changes have been made: The build seems to require all the same tools as the Frosty Tee, but with the addition of a welder. It does not seem to offer improved performance in its current form. My guess would be that the hex end cap offers some obstruction to airflow, and that the depth of the hex end cap also causes the gas jet to be further into the throat than is optimum for air induction. If the burner will not achieve the required temperature as it is, there is some scope for trimming back the mig tip to try to increase induction. If this does not get it there, it seems likely that the hex cap will need to be re-welded with a reduced insertion depth to reduce the obstruction to airflow. Between about 12.35 and 12.50, the video tells us not to use Galvanized pipe because welding it is bad for ones health. This is a couple of seconds after welding on a PTFE tape-sealed joint. Scary. I'd suggest the video poster (Ezra?) do a little research into the thermal decomposition products of PTFE and their health effects, then post an appropriate warning with the Youtube video.
  6. another newbie

    The Nalco 1144 data sheets give an SG of 1.29 and a 15 nm particle size. The concentration is higher than the commercial rigidizers that I have used, which had an SG of about 1.1, so you should have no problem diluting it with water to a similar concentration to the ones I've used. They've soaked in very well and have stiffened the blanket to the full penetration depth on drying. Full rigidizing requires heat and I've not yet felt the overpowering urge to disassemble a working forge to find out how deep the rigidizing has gone, though I'm pretty sure it won't have got hot enough to harden beyond an inch or so. Something to be aware of for those making their own rigidizer from "fumed silica" and water is that the particle size is very important for getting high-concentration suspensions. From reading as much as I can find online, about 15 nm seems to allow the highest concentration. Before I started researching it, I'd already tried Cab-O-Sil M5 fumed Silica and just could not get the SG of a clear suspension above about 1.03, even with the addition of Caustic Soda and every readily-available surfactant I could find. Mixing immediately before application to get a cloudy liquid with higher SG left most of the extra solids as a snowy surface layer that didn't help at all when it came to applying a hard-face coating on top. Multiple applications of the clear M5 suspension seemed to give similar results to a single application of the commercial stuff, but the drying time between each application was excessive. It might be ok for those in warmer, drier climes though. Here in North-West England, it's not something I'd recommend.
  7. Flash back arrestor

    Flashback arresters are usually used in Acetylene lines because Acetylene can undergo explosive decomposition in the absence of Oxygen. Propane cannot, so flashback arresters are not needed. Flame arresters (a different thing) are usually used in lines that may carry a fuel/air mixture and are intended to stop a flame travelling along the line. This is usually because there is deliberate fuel/air mixing or because there is an identified fault condition that could cause a fuel/air mixture to be present. In many cases, it is because the line may sometimes be under suction. For a Propane-fuelled Naturally-Aspirated burner, there is not usually a mechanism by which the fuel line could be filled with a fuel/air mixture, so a flame arrester is unnecessary. Some blown burner designs may have failure modes that would allow a flammable mixture to fill a line: for example, if the blower fails. It is usually much cheaper and easier to design the fault mode out than it is to fit a flame arrester. A solenoid valve in the gas line that is powered open only when the blower is running, for example.
  8. Rolling Mill Motor and gear reduction

    For speed reduction (i.e. any frequency below the rated frequency of the motor: 60 Hz or 50 Hz, depending on location), the motor gives constant torque. For increased speeds (above rated frequency), the motor runs at constant power. This means that there is no problem if the motor sizing is based on the torque requirement, but may be a problem if it is based on the power requirement. In Jspool's example, the VFD speed reduction to 22/29ths of the rated speed will maintain full Torque, but provide "only" 22/29ths of the rated power.
  9. Forge burner not burning well

    Have you tried it in a forge yet? If it is going to work in open air, then trying to tune it in open air makes perfect sense. However, if it is going to be used in a forge, tuning it in a forge is the sensible course of action. The forge massively changes the conditions at the tip. With a forge full of flame, there is flame drawn to the edge of the burner nozzle and this keeps the main flame attached. Which thread was bad and leaking in the first one? If it was leaking gas that got drawn in to the burner, the extra (leaked) gas will have changed the mixture ratio. Might this explain why things were different once you stopped the leak?
  10. Gameco (alec steel) burner

    I don't think I've denied that a photo is important or useful, particularly when trying to understand why a burner is not doing what it is intended to do. If you can show me a thread where I have done so, I'll gladly post a retraction. The point I am trying to make is that a video is basically just a large number of photos in rapid succession and that he has posted quite a lot of video showing these burners in use, achieving temperatures that pretty much any smith I know would consider adequately hot. To date, I have not seen any evidence to suggest that any conventional forge, however good, can provide a working temperature in excess of the flame temperature provided by the burner itself.* It therefore seems to me that achieving welding temperatures absolutely requires a "hot burning" burner. Yet it seems they are indeed hot-burning. It's fairly hard work going through his youtube videos, but it may prove instructive. Hint: I found that judicious use of the mute button helps, as does skipping through as much as possible of the face-to-camera stuff (old age and intolerance comes to us all). He does make the point (in a video where he builds a forge) that he had used the Gameco burners when he was in Australia and was so impressed by them that he brought them into the UK. Corinkayaker's youtube videos probably have a rather better signal-to-noise ratio when it comes to showing the capabilities of the Gameco burners, though I've not found one that shows the burner being used for welding. His "Heat Treating Blades at Home Accurately Aiming for Minimal Scale and Decarburization" video was about the only thing I could find online that demonstrated the relationship between mixture and temperature, back when I started building forges using very similar "Amal" mixers (I'd mistakenly thought all smiths would already know this stuff). The thing that really impressed me was the precision with which temperature can be controlled with a threaded choke adjuster. I'm not 100% certain, but I think the commercially-made burners with a classical Venturi (reduction, very short throat, 1-in-12 increasing taper) provide a much greater air pressure reduction at the throat than the fixed-diameter tube designs, allowing much smaller air intake areas. They certainly look different to any of the shop-built designs, all of which seem to be variations of the long-throat, fixed-diameter-tube design. * Caveat: The Sandia recuperative forges are the only forges that I am aware of that might be considered to do this. I'd not consider these "conventional" and I very much doubt that the burners used in them would be considered mediocre.
  11. Gameco (alec steel) burner

    I'm struggling to understand your point, Mikey. The guy may not be your preferred youtube viewing. He is not mine either. Being irritating is not the same as being wrong (or, as you seem to be implying, dishonest). Why would he want to back up his claims with pictures? He seems to have a reasonably successful business posting youtube videos and there is quite a lot of that video showing him working with those burners, achieving welds which most of us would be entirely happy with. On that basis, he does seem to be backing up his claims. If you are seeing burners that you consider "unlikely to be hot burning", despite the considerable evidence to the contrary, it may be time to re-evaluate what you "know" about burners.
  12. Metric T-Burner

    Many of the mini-migs take an M5-threaded tip (14K) and these are widely available. M5 is also a standard thread for pneumatic fittings. I used a 1/8" BSP to M5 hex reducing bush to fit these mig tips into Amal atmospheric injectors when I was experimenting with jet sizing a few years ago. I never came across a fitting that would make it easy to build a T-burner though. I wasn't specifically looking, but I'm pretty sure I'd have bought a handful if I'd seen anything. The MB360 MIG torches use an M8-threaded tip, available in 0.6mm (which surprised me), 0.8mm and 1.0mm There are also bigger sizes (1.2mm and 1.6mm, maybe others), but they are bigger than "we" are likely to use. There won't be enough meat in the 1/8" nipple to tap out to M8 (tapping drill size for 1/8" BSP is only 8.8mm), but you'd probably be able to find a 1/4" BSP fitting with enough wall thickness to tap M8.
  13. Vanturi burner blowing out with to much air?

    It's not really what I had in mind as a flame retention cup. I'm not entirely sure what the "flare" actually does in most of the burner designs I see out there. In the "classic" Venturi design, there is a reduction to a very short "throat", followed by a 1-in-12 tapered diffuser. As I understand it, this diffuser is intended to slow down the fluid flowing through the Venturi while the flow is still primarily laminar. In the designs where the "throat" is extended to become the full length of the burner tube, the laminar-to-turbulent transition occurs within the extended throat and there does not seem to be a mechanism by which the 1-in-12 taper can work as an effective diffuser. That is not to say that it does not provide some benefit, just that I don't understand the mechanism. When a burner discharges into a forge, the relatively fast-moving mixture causes a slight pressure reduction in the forge atmosphere immediately adjacent to the exiting mixture. This draws the surrounding atmosphere in, just like the fast-moving gas exiting the gas jet draws in air at the Venturi, albeit to a lesser extent because the mixture speed at the burner tip is much lower than the gas speed at the jet. Because the forge atmosphere is effectively all flame, this means that flame is being drawn to the emerging mixture and this stabilizes the flame on the burner nozzle. It makes a huge difference to flame stability and is why it is pretty pointless trying to tune a forge burner in open air. A flame retention cup is usually a sizeable step-change in diameter (typically to twice the diameter, 4 times the area) and, as I understand it, works rather like a miniature forge, setting up a toroidal (donut-shaped) ciculating flame on the step of the retention cup and stabilizing the flame. When a flame retention cup seems appropriate, the flame design I tend to use is more-or-less as shown in the Amal atmospheric injector leaflet. http://amalcarb.co.uk/downloadfiles/amal/amal_gas_injectors.pdf Though I don't use a burner port nozzle as shown in the Amal drawing and I tend to weld something up from whatever is to hand. For a 1/2" burner, I'll slip a 1" length of 3/4" pipe over the end and then slip a 2 1/2" length of 1" pipe over that to get a 1" id retention cup about 1 1/2" long. I've not found the dimensions to be critical, but I've always stuck to a cup of twice the burner ID. About the only time I use a retention cup in a forge is when I am aiming for very low temperatures for heat-treating (around 800 degC, 1572 degF or a little less). In this case, the flame is extremely rich and I want to give it all the help I can. For forging or welding temperatures, I don't use a cup. It's the only pic I have that shows the retention cup at all.
  14. Vanturi burner blowing out with to much air?

    I don't think there's a problem with that flame, unless you intend to use it as a torch. How does it fare in a forge? That's the only thing that matters with a forge burner. There are certainly things you can do to make a burner work "better" in open air (a flame retention cup, for example), but they tend to adversely affect performance in a forge.
  15. Jay Hayes Clamshell Kit?

    I think the correct spelling is Jay Hayes, for anyone else googling it.