timgunn1962

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About timgunn1962

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    Lancashire, England
  1. Question about lining.

    Maxwool is a Nutec trademark. Kaowool is a Morgan Thermal Ceramics trademark. Otherwise, you'd really struggle to find a difference between them. The Maxwool will be fine. Going by the Kaowool TDS, the 8 PCF is a better insulator than the 6 PCF. It certainly seems stronger/stiffer in use. For us, it is definitely worth the extra money. I've not seen a full Nutec TDS, but I'd expect the Maxwool to be the same There are 2 useful grades of Maxwool: HPS (2300 degF) and HTZ (2600 degF). The HTZ incorporates some Zirconia to achieve the higher temperature rating. If you are buying a roll and have any plans for welding in the forseeable future, the HTZ in 8 PCF is the stuff to go for. 1" thickness is probably the most useful. If you are only ever going to be shooting for forging temperatures, the HPS will be fine. It's worth noting that the rating temperature is usually based on permanent shrinkage, rather than a melting point or other catastrophic failure temperature, so the 2300 degree-rated blanked will not suddenly become a dribbly mess at 2301 degF. It will still work pretty well in a welding forge, even a hot one. I picked up a roll of the 1", 8 PCF, Nutec HTZ for cheap a few years ago and made several forges with it. None of them was perfect, but the HTZ was certainly not to blame for any of the shortcomings. I've been looking for more since my supplier closed down. As an aside, (Materials) Safety Data Sheets are not often particularly helpful when comparing products. They are usually written, by people who specialize in writing them, to provide only the legally-required safety information without giving away anything that might be commercially sensitive or useful to a competitor. Often they are all the information you have. When dealing with refractories, even the Technical Data Sheets are limited. They will not normally tell you how prone to cracking on fast heat cycling a particular IFB or castable is for example. For that sort of information there is no substitute for real-world experience. If you can get hold of one of the real technical project guys/gals at a major refractory supplier and pick their brains, you can learn a lot very quickly. They get involved in the big-ticket industrial projects and tend to be well protected from penny-ante timewasters who only want one roll of blanket every few years (i.e. me and, probably, you), so getting to speak with them is seldom easy. Otherwise you are stuck with either picking up whatever collective knowledge has been acquired on sites like this one, or doing the donkey work yourself.
  2. Gas Forge Build

    Dry it out as well as you can before applying fire. It's usually no problem firing with the burner to heat-cycle the rigidizer unless the blanket is still pretty wet. In that case, the steam produced will tend to cool and richen the flame. It can even be sufficient to extinguish the burner completely. If it happens to you, don't panic. It's often only a problem because it's the first time the burner has run, it has not been tuned and it is having to cope with abnormally steamy conditions. Get things dry by other means before making any adjustments.
  3. Reil Burner Problems!

    What pressure are you running it at? Burning back down the tube is usually an indication of insufficient flow. The mixture needs to be flowing towards the nozzle faster than the flame moves through the mixture. Normally, I'd say try turning it up. However, without the forge to stabilize the flame, the odds are high that you'll go straight from burning in the tube to flame lift-off as you turn it up. You really need it in the forge.
  4. Reil Burner Problems!

    Copesy, The little DIY minimig welders over here tend to use MB14 MIG tips with a standard M5 x 0.8mm metric coarse thread, so suitable tapping drills (4.2mm) and taps are easy to find. The tips range from 0.6mm to at least 1.0mm wire and the holes will be about 0.15mm bigger than the nominal wire diameter. I have 0.6, 0.8, 0.9 and 1.0mm tips with M5 threads. As well as being small in diameter, the M5 tips are short, so should not have too big an influence on the inlet airflow. If the standard sizes are not ideal, you can always open them out. When I have played with non-standard jet sizes, the starting point has been a MIG tip that is too small, then open it out one drill at a time with a set of 60-80 number drills and a pinvice. The MIG tips are copper and quite grabby, but spinning the pinvice by hand and only going one size at a time has been fine. Do not waste your time trying to tune your burner out of the forge unless you intend to run it out of the forge normally. The forge automatically stabilizes the flame because the forge atmosphere is effectively just a mass of flame. Faffing about with flares and flame retention cups to get a similar effect outside the forge is all well and good, but the big lump on the hot end of the burner just makes mounting the burner more awkward, and prone to burning away or melting.
  5. Forge dosent seem to be getting enough air

    There is a lot of room for improvement, as said above. However, the easiest single thing to do to improve the burners you have is probably to fit smaller gas jets. You clearly feel there is not enough air for the gas. Turning that around, there is too much gas for the air supply. Fitting a smaller jet will reduce the gas supply relative to the air supply and will increase the flame temperature. I would probably aim for a jet diameter around 80% to 85% of that which you are currently running (64% to 72% of the current area), fit the new jets, see what happens and decide where to go from there.
  6. Help! Kaowool Info

    I get the impression from the spec sheets that something quite unusual is going on with ceramic fibre blanket. For some reason, the higher-density varieties seem to have reduced thermal conductivity (i.e. they are better insulators). http://www.unifrax.eu.com/web/Audit.nsf/ByUNID/D0B83D7C069DC6DB85258220006F5398/$File/Fiberfrax Durablanket S EN.pdf This is exactly opposite to the vast majority of insulating materials. I am pretty sure that compressing the blanket will not significantly reduce its insulating ability on a per-inch-installed basis and will most probably increase it.
  7. Reil Burner Problems!

    Copesy, making forge burners can be very rewarding, but it can also be an exercise in frustration. It will not be helped at all by the fact that most of the well-documented designs are based on US pipe fittings and parts. There are some substitutions that can be made without effectively altering the design, but there's something of a Catch-22, in that you won't be able to identify which changes are significant and which are not unless you understand burners well. If you understood burners well, you would not need to build someone else's design. A 0.6mm mig tip is intended for 0.6mm diameter wire. The need for clearance to allow the wire to feed during welding means that the hole is usually about .007" bigger than the nominal wire diameter. In this case, nominal diameter is around .024" and the hole diameter will be around .031", equivalent to a number 68 drill. The biggest factor in burner performance is the Air:Fuel ratio. Using a bigger gas jet than the design calls for will (usually) cause a richer-than-optimum mixture and a reduced flame temperature. In the UK, arguably the best approach is to buy an "Amal atmospheric injector" (now made by "Burlen Fuel Systems") in the correct size for your application. For reasons I will not bore you with, the injectors jetted for Butane tend to work very well in forges: better than those jetted for Propane. Usual disclaimer: I have no affiliation with either Amal or Burlen other than as a very satisfied customer.
  8. Reil Burner Problems!

    1/ Yes. 2/ Yes, but only because you are using Butane (I assume that's 0 degC, 32 degF?) 3/ Probably: it certainly won't help. 4/ Probably: it certainly won't help. Best to wait until you have the correct reducer though. The "this" link in your post seems to return to this thread. Butane regulators are, to the best of my knowledge, 28 mbar fixed-pressure in the UK. Clip-on, rather than screw-in. You NEED a Propane cylinder with a screw-in connection (there are also clip-on cylinders like the Butane ones. Again, these use a fixed-low-pressure regulator, 37 mbar for Propane, and are no use to us) and an adjustable regulator to suit. 0-2 bar is good. 0-4 bar is overkill, but works and may be easier to find. Do not buy a 0.5-4 bar regulator: the lack of control at the bottom end makes it truly horrible to use once lit and unnecessarily exciting to light. Make sure it goes down to zero. You need to build EXACTLY to a "known good" burner design. The majority of the documented designs are for US fittings, making sourcing them in the UK a minor nightmare. ANY deviation from the documented design, however trivial, means that you have redesigned the burner and that you will need to make your new design work: not a problem if you understand burners, but the learning curve is steep and tends to be expensive in either time, money or both. The best advice I can give is to google, and buy, a Long-Venturi "Amal atmospheric injector" (usual disclaimer: I have no affiliation to them other than as a satisfied customer). The range jetted for Butane actually seems to give the best results when running on Propane in forges (without a secondary air supply).
  9. pyrometer

    When testing burners and forges in expectation of things getting properly hot, I use a type S thermocouple, as I have picked one or two up over the years when decommissioning plant. Much too fragile/expensive to install permanently (They are Platinum-based and new replacements would cost around $500 each). They have recrystallized Alumina sheaths 10mm in diameter (about 3/8") and are 500mm, 20" long. The RA sheath is usually considered good to 1600 degC, 2912 degF, but the Type S tables go up to 1768 degC, 3214 degF. For more regular use, I reach for a handheld Mineral-Insulated type K thermocouple, 24" long and 1/4" diameter below the handle. My preferred one is an Omega KHXL-14U-RSC24, which has the proprietary Super Omegaclad XL sheath, but mostly I use 310-stainless-sheathed examples because I can get them cheaply enough to accept their limited life at welding temperatures. It may be worth mentioning that the failure mode I see most with the Mineral Insulated probes in forges is failure of the metallic sheath. When it gets hot, an Oxide layer forms. When it cools, the Oxide layer detaches. It does not take many cycles for the sheath to be lost and holes to appear. Oxygen can then get in, the thermocouple wires Oxidize and the thermocouple fails. Types 304 and 316 stainless steels tend to lose the Oxide layer when cycled through about 850 degC, 1562 degF. Type 310 is a 25% Cr, 20% Ni stainless. The extra Chromium helps it to form a stronger Oxide layer and the extra Nickel brings the thermal expansion coefficient of the metal closer to that of the Oxide. As a result, type 310 tends to hang on to its Oxide layer until it is cycled through around 1100 degC, 2012 degF. The Super Omegaclad is claimed to be good to 1335 degF, 2440 degF. In my limited experience, it certainly seems to last better at high temperatures than 310SS. I find the 310 sheaths seem to last somewhere in the region of 20 cycles to error reading (over-range for the type K, so 2500 degF-plus) before failing. A good bladesmithing welding temperature seems to be around 1300 degC, 2372 degF so it should be enough for most smiths to learn to recognize the correct temperature range. For electric HT ovens, I use type N thermocouples, which are "only" good to 1300 degC, 2372 degF (vs 1372 degC, 2500 degF for the type K), but were developed to be much more stable than type K when used at temperatures above 1000 degC, 1832 degF. Again, I use super Omegaclad when budget allows, 310SS when it doesn't. I tried InfraRed pyrometers in waste-gas burners at work and cannot say I had much success with them. The readings tended to be considerably higher than the Type S thermocouple readings and I felt the thermocouple was more trustworthy.
  10. What temperature rating for ceramic blanket is needed?

    2200 degF rated is 1200 degC. I suspect that it will be the "Low Body Persistence" stuff. Most of the Refractory Ceramic Fiber blankets I have come across have ratings of either 2300 or 2600 degF, 1260 or 1427 degC. The higher-rated ones having a Zirconia content. The RCF blankets have stronger fibers and are physically stronger, as well as having the higher temperature ratings. The LBP stuff has fibers that are designed/formulated to break up more easily and to dissolve, albeit very slowly, in simulated body fluids. The idea being that they will eventually disappear from the human body, rather than remain forever. Over here in Europe, it's getting much harder to buy the Ceramic Fiber blanket, as the LBP products are assumed to be safer. I'd expect things to follow a similar path over your side of the pond. If you can find a source for the 2600-rated 8 lb blanket, and are comfortable using it, it might be a good idea to stock up on it now, while you still can. As far as I can tell, the main reason for the lower rating of the LBP product is shrinkage. It doesn't simply melt at one degree above the rated temperature and fail dramatically. As the temperature goes up, the shrinkage increases. Many industrial applications use "modules": blocks made from concertina-folded blanket with refractory metal supports that are attached to an outer casing when lining a furnace. Typically, the modules are around 12" square and between 4" and 10" thick. When they shrink, a gap opens up between the modules. The greater the shrinkage, the deeper the (V-shaped) gap gets. Where there is a gap, there is less insulation between the process and the casing. Eventually, there will not be enough insulation for the task. The modules can be slightly compressed on installation, which helps a bit, but does not eliminate the problem. I "think" the temperature that gives 4% shrinkage is used as the rating temperature for some LBP modules, though I don't know if this is an industry standard. For forges, we tend to use wrapped blanket and we tend to coat the hot face with a castable refractory layer. This would seem to largely eliminate the shrinkage failure mode. As far as I can tell, the LBP stuff should probably work fine in most forges. The biggest difficulty we tend to face is that everybody tends to do their own thing and the only way we get to find out what others have done is through personal contact or forums like this one. Very few of us work scientifically (change only one thing, make observations, then change one more thing, make more observations, and so on). Very few, if any, of us have equipment to allow us to take objective measurements at each stage. I'm not sure about Sodium Silicate as a rigidizer. I have used it pretty successfully on some forges and I've had failures on others. It certainly works as a rigidizer on my Heat-Treat forges but these are only intended to run to maybe 1000 degC, 1832 degF. The melting point of Sodium Silicate is given as 1088 degC, 1990 degF. I have had forges with largely Sodium Silicate-rigidized blanket running at welding temperatures >1300 degC, 2372 degF. These were treated by soaking the blanket with a thin suspension of Zirconium Silicate and Porcelain clay in a solution of Sodium Silicate in water. A further forge using the same ingredients but at higher concentrations seemed to result in the coating cracking up and moving on the blanket underneath. I have a feeling the higher concentration of Sodium Silicate solution was largely to blame, coupled with the thicker clay/Zircopax layer shrinking more on drying. However, the forge temperature was taken higher as well and there are too many variables to make an accurate diagnosis. For a forging forge, I'd be happy with Kast-O-Lite over Sodium Silicate rigidized blanket. I would not let the Sodium Silicate solution density exceed 1100 grams/liter, which was what I used on the "good" forges. Make sure things are allowed to dry fully before firing. For a welding forge, I'd spend the money on a commercial rigidizer, 2600 degF RCF blanket and Kast-O-Lite 30. Another variable is the burner. I use burners based on a commercial gas mixer ("Amal atmospheric injector"). This has a very finely-adjustable choke and allows the mixture and flame temperature to be easily adjusted. My forges therefore tend to have more even temperature distribution than most forges built using burners with no choke adjustment. If you have a small, screaming-hot, hotspot in your forge, that's where you are most likely to run into problems with the refractory materials.
  11. Forges 101

    Has anyone reported any success with the Zircopax/VeeGum as an applied lining yet? If so, I think I've missed it. I do seem to recall someone (Maarten?) having some success with stand-alone tiles and thin surface coatings. I got the impression that they knew their way around ceramics a bit and had knowledge that those of us with no ceramics experience would need to acquire, probably the hard way. Making stand-alone sections would seem to eliminate many of the shrinkage issues that occur when different materials are used together. Shrinkage rates with the clay/Zircopax mixtures I've tried have been pretty severe. Once they get to about 1/8"/3mm thickness over rigidized kaowool, the shrinkage means they crack up quite badly on firing. Drying times are also tediously long. I've been using porcelain clay and Zircopax, not Veegum/Zircopax, so YMMV. The porcelain clay is primarily Kaolin/Alumina with added plasticisers, some of which are likely to be Bentonites. Bentonites really do not like letting go of water. I'm not saying it won't work. There may well be further mileage in the Zircopax/Veegum as a liner, if you are of an experimental persuasion. Unless there's a "this is how I did it and it worked really well for me" somewhere that you can follow, it WILL be experimental. If your main objective is to get on with forging stuff, a digression into forge development may not be for you. A thin (brushable) Zircopax/Veegum mix should be fine as a surface coating. I've had no problem with thin coatings of the Zircopax/China clay. I really don't see the shrinkage of Zircopax/Veegum being compatible with the huge cast block that is a ribbon burner though. Far better to use a commercial castable refractory formulated by experts to give minimal/zero shrinkage on (water-) setting and minimal thermal expansion (as this, coupled with temperature gradient, is primarily what causes cracking). Setting time for the castable will be hours and drying time will likely be realistic in many climates (cast it one weekend and run it the next). In cooler/wetter climates, it may need moving indoors to dry once the block is set and the messy bit is over.
  12. how to wire up a boiler blower?

    OK. Knowing you are in the UK makes things relatively easy. No transformer needed. Brown Live, Blue Neutral, Green/Yellow Protective Earth. You can wire with a normal 13A plug and pretty much any mains-rated 3-core cable (0.75 to 1.5 square millimetre will be fine). You'll probably need to buy some receptacles (aka female spade connectors) to fit on the spade connections on the motor. Buy from somewhere that sells electrical stuff, rather than automotive bits. There are 4.8 mm and 6.4mm spade widths. Those look like 6.4mm/1/4". They are by far the most common size so if there's not an option, it's pretty safe to assume they'll be the right ones. The red-insulated ones fit wires up to 1.5mm sq and will be the ones you want. Use a purpose-designed crimping tool, the cheap ones are fine for occasional use. I'd fit a 3A fuse in the plug, as the fan is only rated 82W, so should only pull about a third of an Amp. Only run it from an RCD-protected socket. If you are in a property with old wiring that does not include RCD protection, Screwfix and Toolstation sell 13A RCD plugs and lots of places sell RCD adaptors. Use one; there's a decent chance it'll save a life, probably yours. It's a shaded-pole motor and they tend to run hot. You'll probably need to sort out the broken fan on the motor shaft if you are intending to run it for very long. I don't know what was on the front of the casing originally, but it's a pretty safe bet the inlet was a lot smaller than the big hole that's there now. You'll likely need to close it down to a smaller entry with a cover plate. The outer edge of the impeller is visible and it'll leak out lots of air as it is now.
  13. 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.
  14. 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.
  15. 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.