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About timgunn1962

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  • Birthday 03/15/1962

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    Lancashire, England
  1. As others have said, more information is really needed. If it is running outside a forge, it's pretty much normal behaviour for a burner. The gas/air mixture emerging from the burner causes a low-pressure zone which draws additional air towards the burner. If the flame starts to lift, there is nothing to stop it and it may continue lifting until it goes out. In a forge though, rather than drawing fresh air, the low-pressure zone draws the forge atmosphere instead. As the forge atmosphere is basically a big flame, it tends to stabilize the burn on the end of the burner. If you hold a torch to the edge of the burner when running outside a forge, it will do the same thing In a cold forge, it can also happen. It's not usually a problem in a forge built well from well-insulating materials: the forge temperature rises quickly and the forge atmosphere reaches the temperature needed to stabilize the flame, but it can be an issue when trying to dry out a lining for example. In this case, the undried lining is a big heatsink and the evaporating water will also tend to cool the forge atmosphere. The result is that the stuff being drawn toward the burner is too cold to stabilize the flame. In a hot forge, it seems quite rare to have a problem with flame stability in still conditions, though it can still happen when the wind is sufficient to blow the flame away. In my (limited) experience, breezy conditions seem to affect NA burners with less highly-engineered mixing sections more than those with textbook or near-textbook Venturis. Blown burners seem to be even less affected and may be a better choice if your forging conditions are likely to be windy. If the intention is to run a burner outside a forge, or inside a forge that needs to run at an unusually low temperature (for Heat-Treating or similar), a flame retention cup can often be used to provide a "miniature forge" in which a toroidal (donut-shaped) ring of flame is established on the "shelf" of the retention cup and this will often stabilize the flame sufficiently. I tend to do this when building forges specifically for HT, but do not find is necessary for forges intended for forging or welding.
  2. Realistically, probably not. It's a pipe-or ribbon-burner and works very well for things like heating fish kettles, barbecues, boilers etc where the hot zone being heated is not particularly hot and the tube does not get hot enough to become an ignition source. The narrow slots (or often small holes instead) are narrow enough that the flame-front is robbed of its heat as it tries to pass through the slot/hole and the flame therefore stays above the burner. Put it into a forge at HT temperature and the heat soaking into the tube is very likely to raise the temperature to the point at which the inside of the tube becomes hot enough to ignite the gas/air mixture in the tube. If Wikipedia is to be believed, the autoignition point of Propane is 455 degC, 851 degF. That is well below Austenitizing temperatures. A pipe burner might be ok for a tempering setup though. Ribbon burners as used in forges tend to use a big lump of insulating ceramic ("about" the size of a brick) with holes cast or drilled through it to stop the heat soaking back into the plenum, which is usually steel and outside the forge for cooling, to overcome this problem.
  3. If you are sizing your gas jets to get the mixture you want, either by altering the hole diameter or by altering the length of the jet, you'll need consistency. In theory, if you have a leak that is repeatable so that every time you take the jet out to modify it and put it back in, the leak remains the same, there is no problem. As soon as the leak becomes a variable that affects the mixture ratio, it will play merry games with your burner tuning. In practice, ensuring your leak is consistent would be both onerous and pointless. Sensible folk just avoid creating leaks. The tape vs goop argument will go on forever. I made the move to anaerobic sealants about 30 years ago because I found it just did what I needed it to do with no fuss and, very importantly, no leaks. Something I've not seen mentioned much is that using tape needs care and some skill. Whilst it's a long way from brain surgery and can be covered in a 10-minute show-and-do, I'm guessing most of the guys asking the tape or dope? question are doing so because they genuinely have no idea. They won't have had the 10-minutes of one-to-one instruction from someone who knows and are therefore probably best advised to use an anaerobic sealant, just because there is less chance of getting it wrong.
  4. The baffle reference was from post#2, made by John McPherson, so it doesn't seem to be a case of British and American English terms being different. It seemed like a perfectly adequate functional description of an adjustable choke so, when the discussion seemed to be going off in a different direction, it seemed reasonable to offer the accepted term (which is the same over here). It was intended to make it easier for the OP to follow John's advice: Diamondback offer chokes as an option. I tend to be quite impressed by the guys who have the brains to work out first-hand what is actually going on, and the decency to pass on that knowledge, without necessarily knowing the accepted terminology. Full marks to John. I guess I've spent far too much of my working life around the sort of lower-management pillocks who use jargon unnecessarily, solely in order to feel superior to those who don't.
  5. I am surmising that your concern is over the Superwool's ability to handle the temperature it might see at the interface with the Kast-O-Lite, given its classification temperature of "only" 1200 degC/2192 degF and continuous use temperature of 1000 degC/1832 degF? It is entirely possible to calculate the theoretical interface temperature and make the Kast-O-Lite layer thick enough to bring the interface temperature down to whatever you decide is appropriate. I did something similar a long time ago for a waste gas burner we built at work and found it a PITA, involving some pretty daunting math, a lot of iterative calculation and many, many hours reading textbooks. The main reason I'd not do it for a forge though is that it needs real numbers that few of us have: I'd be pretty surprised to find that more than 10% of smiths could tell you their forge temperature within about 20 degrees, for example. Most of us basically just copy what others have done until we build up enough experience and understanding to work out how to improve things ourselves and, if we do a good enough copying job on a good enough initial design, improvement is not always needed. The Superwool does not melt at 1201 degC, or even close to it, so exceeding the classification temperature, even by some considerable margin, is not going to leave you with a dribbly mess and no working forge. In your shoes, I'd have no qualms at all about using an inch of Kast-O-Lite 30 over rigidized Superwool. In reality, I'm inclined to suspect that the biggest issue you'll have to contend with in respect of longevity is getting the forge properly dried out before first firing. Incomplete drying causes the water trapped in the refractory to flash off to steam causing cavities which greatly weaken the structure.These cavities seem to join up with temperature cycling. "Build it Saturday, use it Sunday" seems to be a recipe for a short-lived forge. "Build it June, use it August" seems rather closer to the mark, though climate is obviously a big factor. In some locations, it may even be necessary to take steps to slow the drying (though Astoria, OR probably isn't one of them). I'd build it, use it for six months, see what needs changing and build the next one as soon as possible so it can be dried fully before needing to use it. It's worth pointing out that the single biggest non-human factor in determining how well or badly a given forge works is the burner. Be prepared to spend at least as much time researching burners as you do researching the structural parts of the forge and do not make the mistake of costing the burner separately from the forge: A burner made from pipe fittings might look like a huge saving against the cost of a commercial item. However, once you factor in things like taps and tapping drills, the construction materials for the forge, any coating used, the regulator, hose and first fill of gas, the overall percentage saving tends to look at lot less impressive. If the pipe-fittings burner will do what you need it to do, great, that's the way to go. Mention of an HT oven and the size of forge given in the OP is suggestive of bladesmithing to me and I'd expect a burner with air:fuel ratio adjustment to be advantageous in that application.
  6. "Intake baffles to tune the fuel/air mix to prevent scaling" sounds like adjustable chokes to me.
  7. It looks to me like it's 1200 degC rated. http://store.armilcfs.com/high-temperature-insulations-refractories/boards.html http://store.armilcfs.com/pdf/Ceramic_Fiber_Board.pdf There are Low-Density boards rated for both 1200 and 1400 degC. I've not seen one rated for 3000 degF (1649 degC). http://www.unifrax.eu.com/web/Audit.nsf/ByUNID/D600A55D633ECF7685258128001AEAC0/$File/Fiberfrax Duraboard 120 EN.pdf http://www.unifrax.eu.com/web/Audit.nsf/ByUNID/0BDEDE9E3537A2F285258128001B037D/$File/Fiberfrax Duraboard 140 EN.pdf
  8. When you take a look inside the burners, pay careful attention to the jet arrangement. It's worth having calipers and a thread gauge handy so you can measure the threads if the jets screw in. A set of number drills would also be useful to use as go/no-go gauges to measure the orifice size in the jets. Cheap import ones are fine and 50-80 should cover the range you are likely to want. They can be used by hand with a pin chuck to open out jets made from brass or Copper (MIG tips are copper. Most commercial gas jets are brass). Pretty much any Naturally Aspirated burner can be made to work if you are able to tune it by changing the jet size.
  9. I am in the UK so can't answer for the "standard BBQ Propane tank" question, but I strongly suspect the answer is yes. Over here, most BBQs run on fixed low pressure (35 mbar, 14" WC) regulators and the cylinder fitting for these is different to that for the high-pressure regulator needed for most gas forges. The pics are not very clear: what is the discoloration on the pipe half-way between the open end and the nearest burner? It could be that the pipe has a welded blank in there. Easy way to check is to poke something down the end and see if it stops there. If it's not blanked already, it needs to be. I'd be inclined try to arrange some sort of support for the pipe or the burner feed lines to take the strain off the spiders in the burners. If there's any movement that shifts the gas jets out of alignment with the center of the intake bells, even slightly, it will change the air:fuel ratio and make tuning trickier than it needs to be.
  10. What needs decoding? It seems pretty clear to me. It's a lightweight, insulating building block. No mention of it being a refractory, as far as I can tell. It's a (very) good insulator, but is not intended a refractory. If you want to build a house or similar structure and maintain the inside at a different temperature to the outside, it may be a good choice subject to the myriad of other variables to be considered when building a house or similar structure. It is not intended as a refractory. The thermal conductivity of many materials, particularly insulating materials, is variable with temperature. When looking at the spec sheets for refractory materials, they will usually give thermal conductivity at several different mean temperatures. The Ytong specs I can find do not give thermal conductivity at different temperatures. The material is clearly intended as a thermally efficient building material for the construction of dwellings and industrial/commercial buildings, not as a refractory. As a construction material for occupied buildings, the implied temperature range is perhaps -50 to +60 degC (ambient outdoor temperatures), roughly -60 to + 140 degF on the outside and somewhat less on the inside. Over this limited range, any change in thermal conductivity is likely to be small and quoting a single value for thermal conductivity seems valid. A example of a specification sheet for a range of Insulating Fire Bricks can be found at http://www.morganthermalceramics.com/media/4526/firebricks-structural-range-1200-1430-data-sheet-english.pdf Note that it includes data relating to the refractory properties of the products. The youtube link in post #2 took me to a forge build using Refractory Ceramic Fibre board: a "real" refractory, though the one that followed it ("gas concrete propan forge...") used Ytong. Nothing in the video suggested to me that the Ytong was likely to make a viable refractory and there does not seem to be a follow-up video showing the Ytong forge in use.
  11. I think the Forgeburners burners are probably imported Aussie Gameco/Artisan Supplies burners. It's pretty easy to find pictures of the outside of them online, but it's what is going on inside that makes the difference to performance. I'd really love to see one taken apart.
  12. As long as you are able to change the jet size to tune it, yes the burner will work or can be made to work. Most likely quite well if you tune it well. However, this is true of almost any NA burner and it does not look as if it will actually perform any better than most of the much simpler burner designs out there. The jet looks to have a step-change in section, rather than a smooth transition from large to small diameter. This suggests to me that you are not familiar with the fundamental principles that apply to NA burners. There is a very good reason to maximize the discharge coefficient of the gas jet, namely to maximize the kinetic energy of the gas. I am pretty sure the reason most of the better homebuild designs use MIG tips is because of their smooth transition into the minor diameter. The MIG tips are designed to smoothly feed wire, but the shape is coincidentally very good for feeding gas. If a smooth transition can achieve a discharge coefficient of 0.8 and a square-edge gives about 0.64, the smooth transition gives 25% higher velocity and 56% more kinetic energy. It's effectively the KE that draws in the air. Although you have included a 1:12 machined bore, it is usually the expansion section after the Venturi throat in the commercial designs. In fact, there is no Venturi throat to speak of, so there is no Venturi. Many (most?) of the homebuild burner designs dispense with a Venturi because, although it can make a significant difference to performance, it's difficult to make one without machining facilities. Your design seems to require the machining facilities but does not make use of a Venturi. It looks like a minor change would make the gas jet location axially adjustable: a no-brainer since you mention that you are unsure where it should be. Unless it's a college project or similar, it would seem much cheaper and easier just to cough up the 65-ish quid (including VAT and delivery) for a 3/4" Amal atmospheric injector. The Amal-style flame retention cup should work fine if you are intending to run the burner outside the forge. For use in a forging or welding forge, it is wholly unnecessary. It can also get expensive if the plan is to use materials for the cup that will stand up to welding temperatures. I use retention cups in dedicated HT forges which run very rich and with flame temperatures around 800 degC (1472 degF) or a little less. In forging or welding forges, I just use straight pipe and an Amal injector. The exhaust area of the forge seems very small with just the round opening(s?). I think you'd probably need the small door(s?) open to run at all. The vertical burner aimed at the centre of the forge floor seems to me to be about the worst arrangement commonly seen: prone to chimneying on shutdown and with a high probability of the flame hitting the metal before combustion is complete, Oxidizing the workpiece.
  13. As Latticino says, the PID controller is a controller. You don't specify what it is that you wish to control, so it seems likely that you are just using it as a pyrometer (temperature display)? It's not a problem to do this, but you may need to trawl through a lot of setup parameters to make it do what you want. If it is "just" a temperature readout you want, an ebay search for "DM6801A" will bring up a handheld type K pyrometer that gives very few opportunities to get things wrong and costs under ten bucks delivered (though you'll also need a 9V battery). It takes a type K input and reads temperature in either DegC or DegF (there's a button to toggle between them). If you really want a permanent thermocouple, the 8-gauge one with ceramic sheath is a pretty good option for the reasons Latticino mentions. It is worth noting that type K thermocouples are particularly prone to "drift" when used at temperatures above about 1000 degC (1832 degF) and it would be a mistake to assume that a permanently-installed Type K will remain accurate for very long at typical forging or welding forge temperatures. Things are not nearly so bad at typical Heat-Treating temperatures The SYL2342 controller has relay outputs. If you are looking to control the temperature of a forge using a HI-Lo burner arrangement, it would be a good choice. The Hi stage solenoid valve would be powered through the output relay. It will not directly trigger an SSR though. For use with an SSR, you'd want the SYL2352 instead, which has a 12VDC pulse output intended to drive an SSR. SSRs are usually used where short cycle times are required and tend to be better suited to electric heating than to gas-fired systems. If you are not controlling anything, you will not need the SSR. The learning curve for controllers tends to be steep and mistakes can get expensive. I've been lucky enough to make most of my mistakes at my employers expense. My personal preference for forges is for a long hand-held thermocouple which can be inserted while the forge is adjusted and then removed while the forge is in use. This allows the temperature to be measured at different places in the forge. Unless specifically designed to provide a very even temperature throughout, most forges have quite large temperature variations throughout the chamber. Color can be a good indicator of the even-ness, or otherwise, of chamber temperature but it's nice to be able to put numbers to it. Examples of forges designed for even heating are dedicated Heat-Treating forges and vertical welding forges intended for welding billets of pattern-welded steel. Both of these examples are fairly specific to bladesmithing, though there may be other applications I am unaware of. Given that we are in the HT sub-forum, it seems fair to assume that the OP is either intending to run a forge designed for Heat Treating or is intending to use a general-purpose forge for HT. In my experience, once the burner is adjusted there tends to be little temperature change at any given location unless a further burner adjustment is made so I usually take the thermocouple out when forging but keep it in when Heat-Treating. My preferred thermocouple is an Omega KHXL-14U-RSC-24. This is a 1/4" diameter Mineral-Insulated handheld thermocouple assembly, 24" long below the handle, with a culy cable terminating in a miniature plug which fits almost all type K pyrometers (including the DM6801A and TM902C). The junction is Ungrounded and the sheath material is Omega's proprietary "Super Omegaclad XL", rated for use to 1335 degC, 2440 degF. The upper end of the range is good for checking that forge temperatures are adequate for welding high-Carbon steels. TBH, most of the time I actually use otherwise similar thermocouple assemblies with type 310 stainless steel sheaths because I can buy these much cheaper from the supplier we use at work with no shipping costs. They don't last nearly as well at the higher temperatures though. Apart from the drift issue, the main reason I don't like permanently-installed thermocouples in forges is that they are fragile and, to give useful information, need to be positioned where the workpiece will be positioned. This makes breakage pretty much inevitable for someone of my limited skill. Omega have a lot of information on their site about temperature measurement and control and it's worth a look. A good starting point is http://www.omega.co.uk/prodinfo/thermocouples.html I used to carry a printed copy of the Labfacility Temperature Control Handbook back when the world was young. Everything you could want to know about temperature control in one slim volume. The .PDF can be found at http://www.controlsdrivesautomation.com/orgfiles/ZORGF000011/IPE/Enhanced companies/labfacility/Temperature Handbook.pdf I use the DM6801A pyrometers myself now, having previously used TM902Cs, also from ebay. The TM902C only reads in DegC so there's even less chance of operator error and I tend to think in degC so don't miss the degF reading. I was quite happy with them intil last year when I had a batch of ten of the TM902C handheld pyrometers that were fine up to 800 degC (1472 degF), but had increasing errors once above that temperature. They didn't look quite like the 30 or so "good" TM902Cs I'd had previously, but the visual difference was not enough to show in an ebay photo and I decided it was safest to use something else. I have access to a calibrator at work and always check any personal instruments with it. That's how I found the bad ones. All the earlier ("good") TM902C units were as accurate as big-name units costing much more and the half-dozen or so DM6801A units I've tested so far have been similarly accurate.
  14. I poured 1 litre of Rigidizer into a measuring jug, stuck it on the kitchen scales, noted the weight, poured out the rigidizer, weighed the measuring jug again and subtracted the weight of the jug. I like simple and low-tech, it minimizes my chances of screwing up.
  15. You'll need more speed. Much more speed. The hydraulics look to be the 10,000 PSI/ 700 Bar stuff that gets used for jacks and small workshop presses where small size, light weight and general portability are needed: occasional tool use only. You'll need a pump, cylinder, control system, tank and plumbing that will provide the force and speed required for forging and that are suitable for continuous use: the sort of stuff that runs 24/7/52 in in industry. Max pressure of this will most likely be in the 140-300 Bar range (2000-4500 PSI), so the cylinder will be much bigger than the one currently on the press. There's a world of difference between a tool that cycles to full pressure a few times a day at most and one that cycles to full pressure a few times a minute. The frame of a forge press will usually be much heavier and much more rigid. Welded joints seem to be the norm, probably because bolted joints under cyclic loading tend to start moving quite quickly. Welding brings all sorts of new and interesting variables into the design and the pragmatic approach is usually to make things as big and heavy as possible to try to compensate for the (usual) builders inability to do all the design calculations and stuff that would be done by a full industrial design team prior to going into production. You can be pretty confident that the workshop press has been designed, with stress calculations, to have the absolute minimum weight consistent with not failing in the anticipated (workshop) use. The minimum weight because steel costs money and shipping weight costs money. Not failing in use is important because killing or maiming users also costs money, lots of it. The upshot is that it's probably best to view the press as essentially unmodifiable.