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About timgunn1962

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  • Birthday 03/15/1962

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    Lancashire, England
  1. It looks like a burner design I've seen somewhere before. Did you follow a set of "known good" instructions? If so, did you use the same size jet as in the instructions? Photos in daylight are about the least helpful at showing what is going on in terms of combustion because they don't show the Dragon's Breath. Is there a lot of it? What color is it? The most usual problem beginners make with NA burners, in my (admittedly somewhat limited) experience, is using too big a gas jet. This results in an excessively fuel-rich mixture and a lot of, usually yellowish, Dragons Breath. If it's an easy thing to do, going down a size on the gas jet has a very good chance of improving matters. If you can get a wide-angle photo across the mouth of the forge at night, it'll usually give the guys who know about such things the best chance of diagnosing the problem.
  2. Too much gas, not enough air. Try a .023" MIG tip and see if it gets hot enough to do what you need it to do.
  3. There's certainly a neat broaching oil that works pretty well and it doesn't take a lot of it to work well on the standard oiling system. I'd always assumed it wasn't a soluble oil, though that could just be because I've always used it neat. Having worked under the steel erectors on various sites, there's certainly not enough oil around to give an advanced warning of that hot razor-edged top-hat slug before it hits you. In most cases, I'd have thought judiciously-located blue roll and duct tape could minimize the risk of contaminating anything nearby. There's a solid paste that works well. The Hougen/Rotabroach version is called Slick-Stik. I've not tried that one but have had good results with "Exact" cutting paste, which I'm pretty sure came from Screwfix though they are not listing it now. It's still available through Amazon. It also works well as a general drilling and tapping paste IME, so is probably very similar to the stuff you already have. I've used tallow-based cutting compounds for drilling, tapping, etc in the past and found them pretty good. I've used straight tallow for thread cutting on pipe and conduit with handheld diestocks, but have never tried it for drilling as far as I can recall. Unless there's a vegan involved, straight tallow might be worth a try if the blue roll and duct tape aren't viable and you feel a lubricant is needed.
  4. There are some major deviations from what I would regard as normal practice when it comes to home-made forge burners. The inlet pipe Mikey mentions is unhelpful. I think the designs that use something similar tend to do so primarily as a means to clamp the gas tube in place. Yours appears to have the gas pipe located in the reduced section where it cannot be clamped by that inlet pipe and where it offers the greatest possible restriction to airflow without actually providing any of the Venturi effect the majority of NA burner designs strive for. You also seem to be running without a regulator, which strikes me as extremely unwise. I get the strong impression you do not understand the basic principles and that your lack of understanding goes way beyond anything that could realistically be dealt with in a forum post. For many people, the required understanding comes through observing what happens when things are changed during operation. To reach this stage, it is helpful to have something that is reasonably functional as a starting point. I would strongly advise that you find a design that is proven to work in your application and build (and operate) a burner EXACTLY to that design.
  5. The issue sounds like your Air:Fuel ratio. Your "not enough air" sounds like it's the most likely thing, though much more information is needed for a proper diagnosis. Photos would certainly help, including pics of the burner and a wide shot of the forge in operation. Ideally, there will be a wide shot in the dark across the mouth of the forge to show the Dragons Breath clearly. Bear in mind that "not enough air" is pretty much the same as "too much gas". Depending on your burner design, a smaller gas jet might be a quick and easy fix. When it comes to gas jetting, many people seem to assume that more must be better. In reality, it's a little more complicated than that.
  6. Can you get smaller gas jets for the forge? You mention that you get "tremendous dragons breath" above 12 PSI. This suggests that your Air:Fuel ratio is too fuel-rich. A Neutral flame gives the hottest flame temperature and a very rich flame is quite a bit cooler. Since there does not seem to be any way to adjust the air intake and they seem to be Naturally-Aspirated burners, using a smaller gas jet should lean off the mixture and raise the flame temperature. Although the flame will be hotter, there will be less of it at any given gas pressure due to the smaller gas jet, so the forge may not get any hotter overall. However, if you then increase the gas pressure, you should be able to get the gas flow back up to where it was with the bigger jet and see higher forge temperatures. I'd initially try for a 10% reduction in jet diameter and see how it goes. Going too small will give an Oxidizing forge atmosphere and you'll just produce a mass of scale. You still want some DB, which is a good indicator of a reducing forge atmosphere, Just not too much. With a gas jet 90% of the diameter, you'd have 81% of the area and would need one and a half times the gas pressure to get the same flow as before: (100%/81%)squared = 1.524. I don't imagine you'll have a gauge that'll read to that degree of precision, so 1.5 is good enough.
  7. Run on variable speed, fans follow the "fan laws", perhaps unsurprisingly. On a fixed system (one where there is no adjustable throttling): Flow varies with the speed. Pressure varies with the square of the speed. Power absorbed varies with the cube of the speed. It may also be worth mentioning that flow through a fixed jet varies as the square root of the pressure difference across it, at least for the sort of pressures we tend to get involved with. It stops being true when the speed through the jet reaches the local speed of sound (choked flow), which usually happens somewhere in the region of 30 PSI for Propane. I've seen posts in the past where the poster seems to have assumed that halving the pressure halves the flow. This tends not to be the case in reality.
  8. The first thing to understand about fans is that you will very rarely get the information you want about them unless you are paying top dollar. It's the curve you want to be looking at. The CFM value quoted is almost always the flow at Zero pressure differential. Where quoted, the static pressure is the pressure against a closed discharge (zero flow). You need to know what happens between these 2 points. I think I'd be looking at radial blowers, rather than axial fans, since they generally have higher static pressures and lower headline flowrates. http://media.digikey.com/pdf/Data Sheets/Sunon PDFs/Maglev Catalog.pdf seems to have some actual curves. Axial fans are near the front and the radial blowers are near the back. I have no idea what the prices are like.
  9. On the face of it, the Voltage *should* make no difference. However, when the current available is limited, which it normally is by the circuit rating, the maximum power available on the lower Voltage is reduced. This makes the time for the oven to reach temperature longer and results in more power being used over the cycle. The difference in power cost-per-blade between 110V and 220V is usually pretty small in the real world: unless you fit a power meter to measure it specifically, you are unlikely to notice it. The difference does get larger when higher temperatures are involved. If you are looking to HT some of the Stainless Steels that need temperatures well over 2000 degF, then 220V is most likely the way to go. If you are going to be working mostly with Carbon steels at around 1500 degF, it's much less of an issue. It really boils down to how big and how hot you need to go (big and/or hot calls for 220V), and what power supply you have available. I have a 3 kW, 230V, homebuilt HT oven with a chamber 7" wide, 6" high and 28" long. At the hour mark on full power, it reaches 2041 degF. Once it reaches the temperature setpoint, it cycles power on and off to maintain the set temperature. At Carbon steel temperatures, the "on" part of the cycle is between 20% and 30%. It is considerably more for Stainless temperatures. If we assume that a Heat-Treat cycle takes full power (3 kW) for an hour to reach temperature, half power for an hour to hold temperature and then switches off, that's 4.5 kWhr per HT cycle. If we then throw in an arbitrary 25 cents/kWhr to get a ballpark cost, that's $1.13 per HT cycle. My oven is big and, even though it's on 230V, probably represents a worst case scenario. I don't know what you pay for power: you'll need to check your bill for the price per kWhr, but I'd expect it to be lower. For most makers, the energy cost for HT is likely to be insignificant compared to the cost of grinding belts.
  10. The last commercial colloidal silica rigidizer I used had a density of about 1100 grams/litre. I've not yet tried making my own with fumed silica but I took the density measurement with a view to doing so.
  11. By my reckoning, that's around 2700 cu.in. To be honest, it's so far out the normal range for homebuilt blacksmithing forges that many of the normal rules of thumb won't apply, if only because the surface area: volume ratio will be significantly different. It may be a 2:1 linear scaleup of a "normal" forge, which would give 4 times the area and 8 times the volume. On the other thread (Firebrick Forge Questions), you say "it works great", so it seems fair to assume that whatever you have, it does what you need it to do. For most "normal" applications though, the general consensus would be that three half-inch burners will probably not suffice. As you are apparently in an industrial environment, there may be lots of things you've not told us (high-pressure-air-fed burners, for example) that move the goalposts. Some pictures would be helpful.
  12. To be fair to the guys who have viewed the thread, for most, there's probably not really much information that can usefully be imparted given the contents of the Original Post. You are describing a build that is some way from any of the "usual" designs and you are using a proprietary burner (or two) in it. There are a lot of unspecified variables in there and it's a pretty safe bet that nobody else on here has direct experience of a setup similar to yours. There is perhaps some very general information that could be given, but that's already on the forum and you have presumably either read it and chosen to ignore it or not read it. In either event, adding to the amount of information you are going to ignore is not a particularly constructive use of anyone's time. Being as how I'm a sad, lonely old git with a lousy cold that's keeping me out of the workshop, I've actually got nothing better to do and may as well give it a go. However, it's probably going to mostly be a cranky RTFM. The exact type of brick makes a huge difference. Some are very prone to breaking up with temperature cycling, others less so. If you have one that is prone to cracking up, the thinner bricks will see steeper temperature gradients and this is likely to exacerbate the problem. Whether or not the furnace cement will help much is quite likely to depend on the type of bricks. The Original Post included links to specifications for 2 very different materials, each with what appear to be pretty good descriptions of their intended applications. The details for the castable cement seem to refer to "large voids or cracks" and mention a slab 1 1/4" thick. This would seem to suggest that it is not intended as a thin paint-on coating. It may work really well, but most folk probably use something developed for the purpose. As far as I can tell, the Atlas 30k burners are designed to run the Atlas forge, which seems to have a 2.5" diameter, 11" long chamber. I make that about 54 cu.in. You are looking to run a forge with nearly 5 times that volume on one, or maybe 2, of these burners. There is an oft-quoted rule-of-thumb that welding temperature needs 450 Btu/hr per cubic inch of chamber. For your 263 cu in chamber, that would suggest 118k Btu/hr is needed; about 4 of the 30K burners? Though I'm not personally convinced by the 450 BTU/cu.in figure, it may well be pretty close for general blacksmithing. There are a number of variables to consider, not least the material to be welded. For bladesmithing, I've built forges that easily achieve welding temperature at something under 300 BTU/cu.in. For bladesmithing though, with around 0.8-1% Carbon steel, the temperature needed is likely to be significantly lower than for mild/wrought and the workpiece access opening for bladesmithing can be smaller than for scrollwork or similar. You've said you won't be welding, so the lower temperature will reduce the BTU requirement considerably. I think my inclination, in your position, would be to try to keep the internal dimensions of the firebrick structure pretty close to the Zoellerforge dimensions and maybe try to back up the bricks with additional loose insulation if possible: something cheap and readily available like Perlite or Vermiculite. I'd certainly give it a try without any cement first, since it keeps it easy to modify if you just have the bricks. Once you've got it working to some degree, you'll have a better feel for what needs to be done to make it work better/well enough. Pictures will help a lot, as Glenn says. Don't forget the wide shot(s). All too often there's a tight shot of a forge chamber that's not performing as it should with nothing to show how the burners are set up.
  13. The OP goes on to point out that he's a newbie, but the thread title is "My first Heat Treat Forge Build". This suggests to me that the intended purpose of the forge might be Heat-Treating blades, rather than forging to shape. Outdoor Gater, is this the case, or have I misunderstood? In my limited experience, HT has a very different set of requirements to forging, let alone welding, and a HT forge is likely to look very different to a more conventional forge.
  14. If you are primarily looking to Heat-Treat tool steel, many of the "normal" difficulties might just go away. The difficult thing tends to be getting a combination of flux-resistance, resistance to physical damage and adequate insulation at the high temperatures needed for welding (2300 degF plus). Often, a composite structure is used to provide the overall combination of properties needed: a kiln-shelf floor, resistant to flux and physical damage, over Kaowool blanket for insulation, for example. Your temperatures are likely to be much lower (Austenitizing temperature is around 1500 degF for most Carbon steels) and flux will likely not be involved. If you are not going to be heaving big, heavy lumps of hot stuff into and out of the forge every minute or two, there is likely to be less need for resistance to physical damage. Plistix over rigidized blanket may well be perfectly adequate for your application. I have actually used unrigidized, uncoated Kaowool in forges without any major issues. The health hazard is not to be ignored, but trying to be realistic I use a forge relatively infrequently and the measures I take to avoid the risk of inhaling Carbon Monoxide also contribute towards reducing the risk of inhaling ceramic fibres. As potential risks to my future health go, Ceramic Fibre seems to be a very long way down the list. To be honest, the biggest difficulty I think you'll face is getting the temperature low enough and even enough with a chokeless burner. You have said you'll be using tool steel, but that covers a range of alloys. Many of them need to be held at Austenitizing temperature for several minutes and this is usually the difficult bit.
  15. "Zircon" usually refers to Zirconium Silicate, rather than Zirconium Oxide.