BobL

Thanks Torin. I finally fired up the forge with the new safety features and the upgraded plumbing. The safety cut outs all work fine which I am very happy about. Previously my gas plumbing was a bit of a mess (see post #2) with some section of the plumbing as narrow as 5/16" in diam. Now I have 3/4" pipe all the way from the main line to where the gas line splits into 2 x 1/2" pipes to each of the torches. I only measured the gas consumption for the front torch and it consumes nearly the same as the two torches together did previously. I'm still working out optimum settings but it got a piece of metal up to 1200ºC using just the front torch and then my pyrometer started playing up so I couldn't measure any higher than this It must have got quite a bot hotter because the forge doorway surround started to glowed hot. I had some minor surgery a couple of weeks ago but I'm not allowed to lift anything heavier than 5 lb or engage in anything strenuous for another 3 weeks!

My safety cut off operates instantaneously on loss of mains power to the blower, by switching off a solenoid valve. It also contains an air flow/pressure sensor which kicks turns off the gas if there is any loss of air pressure. This is not as quick as when the mains power fails and takes about 3 seconds to kick in but it's better than nothing. Because I am using mains natural gas which is at a very low pressure (0.2 psi) in my area my BIG problem was finding a gas solenoid that would fully open under such a low pressure as most switches require more pressure than this to drive them fully open. When I investigated solenoid valves most would not open fully and restrict the gas flow too much plus the correct low pressure valves cost ~$150 .I was lucky to find one amongst a a pile of used valves that were being thrown away during a big clean out at work. One problem with using an air pressure based cut-off is that the air flow sensor has to be bypassed on start up so a few switches and indicator mechanisms are needed. Details of my setup are at the end of this thread '?do=embed' frameborder='0' data-embedContent>>

One of the reasons I have not done anything for a while with my forge is because I realized it badly needed some safety features. The major problem was that being a blown mains gas forge, if for whatever reason the forced air supply was to stop, the small blue blown flame would immediately turn into a very large yellow fireball. The fireball would be so big it would engulf the forge and I could not hope to get near the manual gas taps either on the forge itself or the stopcock on the wall behind the forge. Then I would have to run some 20m to the next stopcock back up near the house. The air flow could stop for any number of reasons e.g. blower failure, mains power failure or I could just put a red hot piece of metal through one of the plastic air supply hoses. After much mucking about, this is what I came up with to automatically turn off the gas on air flow failure. It all starts with the psuedo Pitot tube. One copper tube points into the air stream and the other is perpendicular to the air stream which generates a small but measurable pressure differential under air flow The pitot tube is mounted in a 3/4" T fitting so that the ends of the copper tubes are in the middle of the air stream passing through the forge torch The pitot tubes are connected to this air flow switch ($20 from fleabay) using 2 pieces of black irrigation tubing - sorry its so hard to seeing being all black The two blue taps are air pressure bypass monitors that I can attach to an air pressure meter to set the switch triggering point. The switch is adjustable from 0.1 to 10" of WC. I have set it so that when the air pressure falls below about 0.2" of WC the air flow switch opens removing power from this 24V solenoid valve. Interestingly got the solenoid valve out of a dumpster at work as they were having a major cleanup. The valve was part of a water cooling control panel for a vacuum furnace. It's indeed amazing what is thrown out. The fancy looking ex-CPU fan and heat sink have been added to cool the solenoid which gets quite hot as it really meant for use use with water which would carry the solenoid heat away. Unfortunately nothing is quite as simple as what I have described above as lighting the flame requires no forced air but some gas, so the air flow sensor needs to be temporarily bypassed while the flame is being lit. So I made up this control box (grey box in middle of photo) that has a few bells and whistles to enable a safety aware startup to take place A small switch temporarily bypasses the the airflow sensor. At the same time the bypass displays a red LED and sounds a piezo buzzer to warn the operator that the airflow switch has been bypassed. The operator can then manually open the gas line just a whisker to light the gas (this generates a yellow smokey flame about 150 mm long) The the air supply is turned on just enough to get the flame approaching a green colour. Then the gas is turned up some more, the air some more, and this is repeated until a satisfactory flame is generated. At this point the air flow is sufficient to keep the air flow switch closed so the bypass switch can be turned off. This also switches off the red LED and the buzzer, and also switches on an orange LED If the power fails at anytime during start up the solenoid will still active and turn the gas off and the orange. The control box contains the 240/24V AC transformer and the rectification circuits for the LEDs and Buzzer. I can't use the forge for blacksmithing for another 4 or so weeks due to some surgery I had a recently but I will at least fire it up tomorrow and do some testing with small flames . I also got myself a CO and mains gas sensor/alarm so that I don't gas myself in the process.

My understanding is the horse shoes will be custom made for each hoof by scanning the hoof with some sort of 3D scanner which is sent to the printer via the internet and 24 hours later the shoes are ready for use. The custom made Ti horseshoes are really just a demonstrator of the capability of the metal printing facility by horse and sport obsessed Aussies will to pay bet silly money on two flies crawling up a wall . Elsewhere in the world 3D Ti printing is being used to make custom made all sorts of useful stuff like replacement bone inserts /implants.

I agree the reporter made a bit of a mess of the story. The technical details are here http://www.csiro.au/Portals/Media/CSIRO-leads-additive-manufacturing-charge-with-new-titanium-facility.aspx

Not exactly blacksmithing but perhaps interesting nevertheless http://www.abc.net.au/news/2013-10-17/an-horse-shoe-printed-by-3d-to-improve-racing-performance/5027306

Sorry. Look at the lowered pass thru on the forge in the next (Nicks) post - you should do something like that on yours.

I have seen a curtain rod with ~120" spacing between brackets made from a thin walled steel tubing. To help counteract the sag in the middle, the rail had a decent amount of overhang past each of the brackets and the overhang was filled with lead shot. Of course to do this you need the space for the overhang.

My 18 year old nephew came over with a plough disc yesterday after noon and I helped him make this basic forge from some bits and pieces I had laying around my shop. Nephew cut, filed and drilled and I welded and turned out the air outlet recesses. I let nephew have input into the design which is why it is so high, I'm hoping he can learn from this experience After taking it home in the late afternoon he went out and bought some charcoal and after dinner fired it up and made some metal hot. The blower is one I made for my gas forge but I probably will stick with my Vacuum cleaner so nephew can use it till he finds something suitable.

If your coolant pump has had it you can always add something like this. The pump is a cheap aquarium pump inside a 6" diameter length of capped PVC. Cheap aquarium pumps use a magnetic rotor so you will need to keep the fine swarf out of the coolant tank or it will jam the rotor. I use a couple of rare earth magnets in the coolant collecting tray to trap the swarf. Occasionally some swarf will sneak past so I have to remove the pump and clean it out.

Looks great. I'm dead jealous.

About as many as there are are pieces of the real cross.

Yep - that one is on the drawing board. The problem is getting a solenoid with a long enough throw, or the other design is a spring loaded handle with a short throw solenoid to unlatch the spring loaded handle. Just trying to design something as simple as possible. I have had to stop using the forge until this control is hardwired into the pluming. If the blower stops for any reason (most likely from a mains AC power failure) the small blue (ie blown) flame instantly turns into a yellow 6+ ft diam fireball. I really should use an air flow sensor to switch the solenoid that way if either the AC power failed or the air lines came off or the blower failed it would turn the gas off. ANy good ideas would be appreciated. Thanks

Good job medicmc, I'm considering doing a similar thing with my mains gas powered forge. The big problem I have is that I need a 3/4" solenoid valve that fully opens without any gas pressure assistance since mains powered gas has so little pressure. These valves are available but they cost big bucks here in Australia and I'm trying to find a used one I can trust, or might have to make one from bits and pieces. I had an idler circuit on my previous set up, more to reduce the heat build up inside my shop when I was not working the metal than to reduce cost as the forge only costs $2.50/hour to run

All of the squirrel cage fans in that thread look like they are appropriately sized (ie smallish) to better match the needs of a forge. It's just a guess but with a 6" diameter forge air intake it sounds like sarcat2012's fan is a bit bigger that these.

If it is a largish squirrel cage fan it will be designed to operate correctly at higher ~500+ CFM flow rates but only with a very low back pressure. Forcing such a fan with a high output to run at full speed just to get the required flow through a narrow duct is severely restricting its output so that it will just end up spending most of its time running at full speed with its impeller cavitating ie stirring the same air round and round, which just heats up the air and will overheat the motor. Many squirrel cage fans do not generate the pressure required to force air through small pipes plus a forge on the end of the pipe. Many Inline duct fans also cannot generate much pressure so there is no guarantee that it will work either.

I agree with the comments by others of the dangers of using a gas forge indoors, insurance issues etc so will just comment on ventilation via a 4" duct. The most any standard low pressure fan or impeller can pull through a 4" diam duct is ~400 CFM. Higher pressure fans can force more air through a 4" duct but it will then scream like a banshee. There is also a temptation to say, eg my cellar is 20 x 20 x 9 ft = 3600 cf so ~ 400 cfm should replace the air every 9 minutes. This can only happen if the air inlets and outlets are evenly distributed on opposite walls and something called laminar air flow is achieved which required nothing blocking the airflow path across a room. In practice, with say a doorway inlet on one wall and a 4" outlet one the other a 400 cfm extraction can at best achieve one complete room air replacement every 18 minutes and most likely every 30 minutes. 6" ducting is better (limited to ~1250 cfm) provided that the driving fan also can deliver that but even that may not be sufficient. FWIW I'm using a natural gas forge inside a ~3600 cf shop and even using a 1300 cfm squirrel cage fan, after about half an hour the shop starts to get hot have have to switch on additional ventilation. I really need to get myself some CO/NG sensors to keep a track of what is going on.

Love it!

Like it's ferrous counter part the snake is a fake (rubber). Up close it's not as realistic as the OPs beauty. I first posted the picture on a an international milling forum in 2009 without saying it was a fake and got some interesting responses. Most Aussie snakes are quite poisonous but will slither a mile to avoid chainsaw noise so the first thing you do before approaching a tree/log is to run the saw for a few seconds and they will take off. The rubber snake is the landowners, he has a dog that loves chasing snakes and so they were hoping to train the dog from not doing so using a fake snake. The dog still chases snakes but nearly 5 years later it is still alive. The saw guide is a Westford. It's an Aussie equivalent of the US made Granberg Mark II Alaskan mill. Most alaskan style mills can use a ladder as a guide,

I like the snake. Here is my favorite snake photo. BTW that's me cutting up the log.

I love mountains, too bad I'm living on the flattest continent on the planet. Lots of other benefits though. :)

A Natural form can be seen in meteorites called Pallasites. Put pallasites into Google images and you will see some interesting stuff. The conditions under which this happens are "unusual" - it's though to occur at he boundary between a planet(ismal) liquid Ni-Fe and molten rocky cores.

Put "hematite" and "magnetite" into google images and you will get heaps of images. As for the bloomery do a You Tube search for "iron bloomery"

Love it - would be good to find out some of its history.

While the site has been down I had a crack at making a fullering guillotine The blades are cut out of very tough 3/8" mm thick hardwood chipper blades. I tested out how well they would withstand use by putting on all the PPE I had and then belting them edge on with a large sledge hammer. They did not chip but started to mushroom after about half a dozen blows. The body is made from a 3 x 3" x 3/16" SHS section so it is intended for smallish stuff. I have a piece of 4 x 4" x 1/4" SHS and some 1/2" chipper blades to make a bigger one if I need to. As I only have a small (112 lb) anvil, rather than a hardy hole mount I decide to go with a chunky 5/8" cross clamp so it could be mounted in the middle of the anvil. The blade can be held at any height with this spring loaded friction pin. This allows the top jaw to be held open before withdrawing the workpiece from the forge. After placing the workpiece on the bottom jaw, a sight tap of the top jaw with a hammer will drive that jaw onto the workpiece There is also an end stop available if needed. The metal pieces were cut with out an angle grinder and tidied up using a grinder and linisher. The machines used were a welder, drill press, and a lathe to make the big swivel lock. I'm quite pleased with the way it works