timgunn1962

You should be fine on the lower voltage. The car battery should give the current needed (the rating is likely to be a bit of a lottery, but working on 3.5 HP being 2625W, 2625W/130V gives 20.2 Amps as a ballpark figure). That's a fairly high current for a charger, so the battery is probably the safest bet unless you have a charger rated for high current. Speed varies with Voltage, so will be low: about 10% of the rated speed at the 12-point-something Volts a car battery will give. Should be fine for checking tracking and alignment.

Ken, I've not tried PID control on a forge myself. To be honest, I don't think I can see enough benefit to justify the effort for anything except Heat treatment. I've seen PID control used on a Don Fogg-style 55 gallon Heat Treat forge and it was excellent. To be honest, it wasn't very much better at holding a given temperature than a manually-controlled Don Fogg-style 55 gallon HT forge though. If I was building a gas forge for myself for HT, I'd probably go with the PID-controlled Don Fogg design, simply because I am too lazy to spend the time tweaking the temperature manually and I do enough process control in my day job that the PID stuff is almost second nature. For anyone who makes a living from making and HT-ing stuff, the PID would pay for itself very quickly by eliminating the need to spend the time making manual adjustments each time. It is specifically for heat-treatment though. In your shoes, I would not add the ceramic sheath. If you do, it will slow the response of the thermocouple to temperature changes in the forge; the display will tell you the thermocouple junction temperature is more stable, but the actual workpiece temperature will almost certainly see bigger swings. Been there. Done that. If/when you try it, I'd strongly recommend using a fast-responding thermocouple and a hand-held display to check what is going on before and after you fit the sheath (I wouldn't believe someone I've never heard of telling me stuff that seems counter-intuitive on the internet either). The cycle time on your On/Off control could actually be pretty short, depending on your Hysteresis setting and the thermal mass of your forge. It's worth timing it, as whatever it turns out to be should give a "safe" cycle time for PID control ("Safe" meaning no worse than you have at present; I'd make sure I had, or could quickly get, a spare coil for the solenoid valve and maybe a complete valve).

It's probably a case of guess and check. I've built a few burners using Amal brand Gas Injectors and they recommend a flame retention cup length of twice the ID of the burner throat. For a plain 3/4" bore pipe into a 1" retention cup, the 1" cup would add 1 1/2" to the length. The Amal Gas Injector leaflet is downloadable at http://www.amalcarb.co.uk/downloads.aspx In my experience, things are pretty forgiving at the hot end as far as tolerances go. It's more the gas:air mixer end of a Naturally Aspirated burner that is worth getting a bit obsessive about, since it makes such a big difference to how well the burner works.

The thinners is probably cellulose thinners. It's basically just something to dissolve the ATF (which is effectively just an oil) and get it into the gaps by capillary action. Acetone, cellulose thinners and Methanol have all worked for me, when I've needed to soak stuff. It's only really worth faffing about with if you are going to soak though, or you have thinners, etc, and ATF hanging around anyway. Usually I use "PlusGas" if it's a case of needing to spray something on. I'm sure there are other proprietary products that are better (Kroil is supposed to be), but PlusGas is the best I can usually get hold of in the UK. Gentle heat and penetrating oil usually works too, just slower. I'm fairly sure "transmission fluid" will be ATF.

Assuming it's marked using the old British weight system, it should be Hundredweight, Quarter-Hundredweight, Pounds. A hundredweight (CWT) is 112 lb A Quarter Hundredweight is 28 lb A pound is 1 lb. A 110 lb anvil would be 0,3,26 A 120 lb anvil would be 1,0,8

Don't worry too much about researching the number of burners. The correct number will be one. I'm sure everyone else will greet this with derision, but you'll need to mount it in the end and have it sending the flame along the forge and straight out of the end. I built a couple that way and took them to a hammerin, two or perhaps three years ago. Quite a number of knives got forged using them over the weekend. Lots of people said they'd do it differently. To be fair, I would do it differently as well. They came about because I had some scrap stainless pipe and odd bits and pieces to practice welding on. I had been wanting to make a mini-forge of the coffee can or paintcan type so, rather than making abstract art, I welded a couple of ends on some 6" pipe. I already had a few square feet of Ceramic Fiber blanket and a couple of cheap Chinese torch sets that I felt I could probably modify to work in a forge. Basically, it was a case of making something from what I had to hand. The burners were horrible to use and I would not use them again. I got them to work, but each one had to be treated as a one-off (I'd hoped I could modify one to work, then do the same with the other one and have it work as well). I've since been playing with Venturi burners and have also used one or two blown burners. Either would work in a tube forge like yours. I'd advise building the best burner you can, as you'll outgrow the tube forge quite quickly and want to build something else. It's a lot easier and quicker to get a new one up and running if you've already got a good burner for it. The photo is while I was testing it. I had a type S thermocouple in it and I was just trying for hot at the time. It showed 1368 degC (2494 degF). For forging, it was run somewhat cooler. Downsides to the configuration are that it probably needs to be run fairly hard to minimize the temperature gradient, and that work is more awkward to handle because you cant selectively heat the bit you want to hit. It will get you started though

What are you intending to do with the PID control? If you are using it simply as a temperature readout, so that you can make manual adjustments to get the desired temperature, either burner will get the job done. If you are not using a blown burner, a battery powered hand-held readout will also work and frees you from mains power. With a blown burner, you are tied to the mains anyway. If you intend to use the controller to automatically adjust things to maintain a given temperature (the "PID control" part), the control philosophy is going to be what decides which type of burner is the most appropriate. For welding temperatures, I am pretty sure you'd be needing to use analog control and that's probably more specialized than is wise for a beginner (simpler time-proportioning on/off control can, and does, work well with a Don Fogg-type 55 gall HT forge, but I get the feeling that welding temperatures are altogether different). If you are buying, the Hybrid seems to be well thought-out and, by all accounts, works well. If you are building your own, a blown burner tends to have less exacting requirements when sourcing the parts, perhaps giving more scope for using whatever is available where you are. Blown burners also tend to be less demanding in terms of build accuracy, making them a better proposition for the less-well-equipped workshop; getting the jet perfectly centred is not necessary wth a blown burner, for example. It is fairly necessary, but not necessarily easy, with an unblown design.

It'll probably be the flame burning back down the burner tube. It happens when the speed of the flame-front through the gas mixture exceeds the speed that the gas mixture is moving in the other direction. By turning up the pressure, you have increased the mixture speed to exceed the flame speed. The gas flow through a jet varies with the square root of the pressure, so going from 3 PSI to 5 PSI will have increased both gas usage and mixture speed by around 29%. Many burners have a "flare" on the end; a tapered section in which the mixture speed reduces as the are increases. Somewhere in the taper, the flame speed will match the mixture speed and the flame will stabilize. Other burners have a flame retention cup, which works differently but still stabilizes the flame. There is a step-change in diameter, which sets up a sort of donut of turbulence. The mixture drags some of whatever atmosphere is present along with it in the middle of the donut and more of the atmosphere is drawn down the outside of the donut to fill the space left by the bit that was dragged out. As the atmosphere at the end of the burner consists of flame, the effect is to have the flame continually working as its own pilot. Some burners have neither a flare nor a retention cup, but the step-change where the burner enters the forge chamber has the same effect as a retention cup. The flame speed varies with temperature, pressure and air:fuel ratio. Once the flame-front starts to accelerate, it sets up a pressure wave which increases the flame speed, increasing the pressure and so on, until it runs out of fuel/air mixture and goes out. Then nothing happens until the unburnt mixture reaches the hot forge, where it ignites and the acceleration process starts again. Each time the flame moves down the burner tube, it heats it up a little, which has the effect of increasing the flame speed. You'll probably find that the first couple of hiccups are a few seconds apart, but that the frequency increases if you don't catch it quickly.

According to his profile, the OP is in New Zealand. The power supply system there is, as far as I know, similar to much of Europe and rather different to the USA. A single phase domestic supply is usually one phase of a 415V phase-phase 3-phase supply as the live, together with a Neutral, taken from the Star (Wye) point, at Earth (Ground) potential, giving 240V Live-Neutral. A phase converter to provide 415V 3-phase can be built, but needs a 240-415V step-up transformer as the first part. This adds expense and complexity. It can still be a viable DIY project, but is apt to become a hobby in itself, rather than something knocked together in a weekend to let you get on with your real hobby. 240V input VFDs will usually give 240V 3-phase output. There are rare examples that include a step-up stage to 400V and give their output at 400V phase-phase. They tend to be hard to find and very expensive. Most small 3-phase modern motors (up to about 3 kW) have 6 terminals in the connection box and can be wired in Star (Wye) for 380-440V, or Delta for 220-240V. Above about 4 kW, they tend to be wireable for roughly 400V in Delta and 700V in Star. This is to allow "Star-Delta" starting, which greatly reduces the current draw on initial startup when compared to Direct-On-Line (across-the-line) starting. It's something that tends to be seen on big industrial motors and doesn't seem likely to be of interest to many of us. If you are buying a 3-phase motor to use with a 230V VFD, it's worth noting that the change from 230/400V to 400/700V is not at a standard motor size; it needs checking for the specific motor. Many older motors only have three terminals in the connection box, so can only be run on the original design voltage. Reading between the lines somewhat, I get the impression the OP probably has an old 415V motor on a similarly old Power Hammer. The most practical solution seems to be the one taken: buy a single-phase motor and fit that. I was discussing VFDs with someone who knows a bit about PHs a while back. He seemed to think a VFD on certain types of PH would be useful for the gentle stuff. As I understand it, the blow energy changes with the square of the speed, so it seems like it could work very well. I don't know enough about PHs to have an opinion. The obvious way to find out would be to run a PH from a VFD. However, this is not necessarily a good idea, as most older PHs have old motors. It should be fine on a new one though. The waveform from a VFD is very hard on old motors, and the winding insulation can break down very quickly. It's not usually a problem if the motor has been rewound in the last 30-40 years, as the insulation will be whatever was in general use at the time of the rewind. Motors from about 1970 onwards don't seem to be a problem, at least in my limited experience. As for running a 3-phase MIG, it's worth checking whether it's really 3-phase, or just uses 2 phases of the 3-phase supply to give a single phase at 415V. If the latter, it would run from a step-up transformer. Alternatively, there are some pretty meaty single-phase MIG welders available. I've just got an Oxford S-MIG 410-1 at work and it seems to be a very capable machine. http://www.weldingsuppliesdirect.co.uk/welding/Oxford-S-MIG-410-1-SMIG4101.html

Just thinking out loud really; I have a feeling that the sawdust starts off by losing steam, then thermally decomposing, before the carbon that is left after the thermal decomposition actually burns away. The water loss and thermal decomposition would seem likely to provide a certain amount of early porosity, allowing Oxygen in to burn with the Carbon. Starting with straight Carbon (charcoal), which has already done the water loss and thermal decomposition thing before being incorporated into the mix, would seem to limit the sites accessible to Oxygen to those on the surface. Obviously, the surface will burn away, so the layer underneath becomes the new surface, and so on, but I'd expect it to be very much slower than starting with sawdust. In all honesty, I'd expect it to be too slow to be viable. I'd be happy to be wrong though. If you try it and it works, please let us know.

I think the correct spelling is "Fabreeka" (not wishing to sound like the pedant I probably am, I only mention it because Googling "fabrika" gave no hits on the stuff and no "did you mean...") Conveyor belting seems to work, though I don't know how it compares to the proper stuff. I've taken out machines that have been installed on the cheap using whatever rubber was available at the time; either conveyor belting or some sort of solid rubber mat. On a fair number, the rubber mat seemed to have "flowed" under pressure and was doing little or nothing of any use. The rubber and canvas conveyor belting at least tended to stay in place. I've not really encountered stall mats to know what they are like.

There are lots of different things happening in an atmospheric burner and they all affect each other. Although they are not any more efficient or any hotter when set correctly, blown burners can be easier to set up, because the gas and air feeds are independent. With your atmospheric burner (I'm being pedantic and not calling it a Venturi because not all atmospheric burners use a Venturi), the gas leaving the jet generates a low-pressure zone, into which air is drawn. The air mixes with the gas as it travels along the burner tube. The mixture really needs to be travelling along the burner tube faster than the flame-front can move through the mixture. If the flame-front is moving through the mixture faster than the mixture is moving in the opposite direction, the flame will burn back down the tube. Sometimes this will appear as stuttering and can usually be overcome by turning up the gas pressure. The gas speed out of the jet has more of an effect on the amount of air entrained than does the volume of gas. It sounds, from your description of the yellow flame, like you either have a restriction at the exit from the forge (the volume of hot gases you need to get out of the forge will be at least 5 times the volume of cold gas and air going in, simply because of thermal expansion), or you have too large a gas jet. When you had your nice blue flame out of the forge, what did it look like? I'm guessing you had a tight blue cone (the primary flame), surrounded by a bushy outer flame (the secondary flame). The primary flame is where the gas and the (primary) air, drawn in through the mixer, burn. The secondary flame is where more air mixes with the partially-burnt gases from the primary flame and finishes the burn. If you stick the burner in a forge and don't let air in between the burner and the hole it fits through, the secondary air cannot get to the partially-burnt gases from the primary flame until after they leave the forge. The burner that looked great with both primary and secondary air, now only has primary air and it ain't enough. It sounds to me like you need a smaller gas jet.

Looks a tidy haul, and at a pretty good price. Where in Blighty are you, and did you have to travel far to get them? Can't help on the maker, but I'd have thought a Hay Budden would be less likely on this side of the pond, though stranger things have happened.

I second the "keep it modular" approach. You can get a 152 x 152mm (6" x 6") chamber without cutting bricks if you just pin them together (i use 3/32"/2.4mm welding rod). You can usually make a D-bit from the rod itself that will drill the holes to stick the pins in; Just grind half the rod away at the end to give a cemicircular section for 1/2" or so; the"D" in D-bit. It works best with a starter hole, so to save damaging a twist drill by using it in the brick, I drill a hole through a piece of scrap wood, hold it against the brick and use it as the starter hole. The holes are small enough that they dont ruin the bricks once you take the pins out. For forging and HT, uncoated brick seems fine to me. I use a Venturi burner, so the flame speed may not be as high as yours. YMMV. Pee on snow might be a slight exaggeration, but you really don't want to be getting hot borax on Insulating Fire Bricks. The first, experimental, soft-brick forge I built had a 3/4" lower floor after a single days use at a hammerin, due to borax. The second one i made was very similar. I gave it a welded angle-iron frame because I needed to move it easily, so I didn't adopt the modular approach. I'll need to coat the floor if I ever weld in it. http://s667.beta.photobucket.com/user/timmgunn1962/media/Forge%20With%201inch%20Burner/DSCF0023.jpg.html?sort=3&o=12

It looks like salts number 5 in the Milspec will get the job done. I find that own-brand low sodium salt from my local supermarket does the job nicely; basically, it's half Sodium Chloride, half Potassium Chloride. I'm in the UK, so things may be different where you are. From a quick Google, it looks like Morton "Lite Salt" is pretty similar, though it does contain anti-caking agents. It might be worth checking out own-brand equivalents.

One thing to watch is that a lot of magnets stop being magnetic when they get hot, particularly the powerful modern ones. The "stick a magnet on the workpiece and quench when it drops off" approach is probably not a good one. In most cases, the magnet will stop being a magnet at a much lower temperature than the workpiece will cease to be attracted by a magnet. It's better to heat the workpiece and touch it with the magnet occasionally, letting the magnet cool in between tries.

I don't recall ever seeing a galvanized air receiver.I'm not saying it's definitely not galv., just that I think it's pretty unlikely. It's extremely unusual to see any hollow fabrication just galvanized on the outside. Usually there are holes to let the Zinc in and the air out as the fabrication fills, and the Zinc out as it is lifted from the tank. Most of the receivers I see are painted. Quite a few have a silver-grey hammer finish that could be mistaken for galv. Have a good scrape at the coating. If it chips along the edge of the scrape, it's pretty likely it's paint. Best way is to stand upwind of an off-cut and attack it with a blowtorch. Galv tends to produce a lot of white fumes. often there's a white or yellow-white residue left. Paint tends to smoke and usually there's a black residue. Even paint fumes can be be pretty nasty though.

Keith, Do you have a link to the "manual" for your controller? I've found that many of the cheap ebay controllers are effectively the same, despite appearances, presumably because they use the same processor. None of the manuals are good, but some are less poor than others. If you aren't used to PID controllers, pretty much any controller will induce migraine. Rich, I'd strongly recommend either a CN7823 or a CN7223, depending on controller size, from Omega, or one of the Solo series from AutomationDirect. I like the bigger Solo 9696VRE because the buttons are bigger and I can read it from across the shop, but the 4848VR is cheaper. AutomationDirect seem to have pretty good support too. http://www.automatio...ess_Controllers The other popular controller on your side of the pond is the Auber Instruments ramp/soak controller (I think it's the SYL-2352P). Used in a few of the HT ovens I've seen write-ups for, but not really available here so I have not used one. The Omega and Solo I've mentioned appear to be the same controller, badged differently. They will tune to and store 4 different sets of PID terms at 4 different temperatures, then automatically use the set of terms closest to the setpoint. I like this feature.

"Air dryer" is almost as broad a term as "air hammer". It can cover coalescing filters, refrigerant dryers, dessicant dryers, membrane dryers, deliquescent dryers and probably more I've not come across. Unless you have a severe climate, or an unusual usage pattern for your hammer, a good coalescing filter with an autodrain will probably get the job done. I'd recommend you fit it as close to the hammer as possible, but before the regulator. That way you get the air as cool as possible, making as much condensate as possible, before the coalescer, which will remove all the liquid water and fine mist droplets. The regulator will then reduce the pressure, which has the effect of drying the air, to your working pressure. If you use one, the lubricator goes just downstream of the regulator. Make sure the bowl on the coalescing filter has a proper float-operated autodrain, not a semi-autodrain. The semi-autodrains only drain when the pressure is released; no good if you work for any length of time. Do some reading up on the subject and talk to a few pneumatic equipment suppliers before you pull the trigger. Things can easily get unnecessarily spendy. If a coalescer will get the job done, shop around. The big-name stuff is good, but it ain't rocket science and it ain't new technology. There's some very good stuff coming from the far East at very low prices.

Cromwell in the UK sell a range of similar styled hammers that seem OK for a beginner and are reasonably priced. http://www.cromwell.co.uk/index.php?q=0&p=browse&c=031210&ss=hammer Metric weights, so the 0.8 kg is a bit under 2 lb and the 1 kg is a bit over.

I would expect 1020 to reach that hardness only in a case-hardened condition. The link does indicate that the balls are case hardened. For those unfamiliar with the process, case-hardening is a process by which additional carbon diffuses into the surface, at high temperature, from a carbon-rich packing medium. The entire article can then be quenched, but only the surface, with a high enough carbon content to form Martensite, will harden.

There are lots of different flux compositions, but I can't find anything on "zweld" online. A flux that's primarily anhydrous Borax would obviously give the advantages of anhydrous borax, so would probably be noticeably "better" to use than either the pentahydrate or the readily available decahydrate. I'd certainly expect anyone comparing it to 20-Mule Team borax (the decahydrate) to notice a difference.

You are right; Borax is just the common name for Sodium Tetraborate.

I'm no expert, but I think it might be helpful to take a step back and think about what you use flux for. As I understand it, an important property of flux is its ability to dissolve the metal oxides that would otherwise contaminate the weld, and transport them away from the weld in solution. Because the refractories used in most gas forges are made from metal oxides, any effective flux will give them a very hard time. I think (but I don't know for sure) that the biggest problem with the insulating refractories is the low density and large surface area, which combine to make them dissolve very fast. From my limited experience, both Alumina blanket and Zirconia blanket dissolve very quickly in contact with hot borax. Type 23 IFBs are slower and dense fire bricks are slower still. A hard refractory coating applied to the surface should give the advantage of slow attack, combined with good insulation. The water content of the Borax is inconsequential in terms of how it reacts with the lining, because all the water has boiled off by the time it's molten. Where the water content makes a difference is in how easy it is to keep it on the work. Borax comes as Decahydrate, Pentahydrate and Anhydrous types. Decahydrate has 10 molecules of water associated with each borax molecule, Pentahydrate has 5 and Anhydrous has none. When you apply the borax, the water boils off as the borax melts. As it boils off, the water makes the borax froth and some will inevitably fall off. Ideally, you'd use Anhydrous borax. Next best is Pentahydrate, with the frothiest being the Decahydrate. The most common is the Decahydrate (mule team, etc). This can fairly easily be cooked in a domestic oven to drive off some of the water and get it to the Pentahydrate. To really finish the job and make it anhydrous needs bringing it up to melting, letting it cool and pulverizing the glassy mass that results. The Pentahydrate is easy. Anhydrous is more hassle and not without risk.

Ribbon burners are harder to get right than their apparent simplicity would suggest (in fact this is true of pretty much any type of burner). If you are going this route, it's probably best to copy, very faithfully, a proven design. Whatever type of burner you use, for safety, always bear in mind that keeping the volume of gas/air mixture that is in the system at any time as small as possible, minimizes the energy released if/when things go wrong. Also, minimizing the distance between the start of gas/air mixing and the ignition source (forge in this case), means that there is not much of a run-up over which the flamefront can accelerate to damaging speeds/pressures. To be honest, I'd not actually spotted the 1" and 1/2" line sizes mentioned in the text of your first post (I was too busy panicking and assuming the not-to-scale .pdf was something like to-scale, for which I apologize). They are probably small enough to keep the volume down to acceptable levels. Putting separate gas jets on each burner a few inches before the forge would be a fairly simple modification to the design and would certainly make it safer.