Buzzkill

Hard fire bricks can handle the heat, but they are not very insulating. That translates into more fuel to get the forge up to heat as well as more fuel to maintain temperature. Insulating fire bricks can handle the heat and keep more of it in your forge, but are comparatively fragile - and significantly more expensive. Also, a coating such as Plistex or Metrikote can help reflect more heat back into the forge. The bottom line is that if you are happy with your results and don't feel that the extra fuel used is a problem then you may not need to do anything. Upgrading to insulating fire bricks will cost you more money up front, but should save you money in the long run. Likewise, the surface coatings I mentioned do cost a little bit up front, but may increase the temperature you can maintain as well as save a bit of fuel over time. I'm personally not a fan of a loose brick forge, probably because I feel I'll eventually bump into it hard enough to be a problem. Just an angle iron framework held together with some all thread rod would be enough containment.

One minor issue is that a couple of your all thread rods will be directly exposed to very high temperatures. That is going to result in the zinc being burned off the galvanized rods. It may not be enough to worry about metal fume fever, but with that configuration and materials there will be some amount of zinc oxide in the air when you bring your forge up to working heat. Other than that it looks well designed and constructed to me. Can't wait to see what you do with it.

Looks pretty good to me. Let us know how it works out for you. With that one inch burner there could be an issue getting complete combustion before the flame hits another surface, but you won't know for sure until you try it. If you find you need more height you could flip your vertical bricks around and cut new shelves a bit higher. That would make your top horizontal bricks stick up a little, but it shouldn't affect the functionality of the forge.

Yes, I believe you got what I was saying. If you choose to use your bandsaw to make the cuts, make sure it's a dull blade or one you are willing to sacrifice. A sharp blade will become dull very quickly when cutting soft fire bricks. As far as size goes, my recommendation is to build a forge as small as you reasonably can and still be able to do what you want to do. Large forges with big burners require a lot more fuel (which of course translates to cost). Generally speaking if you are working with hand hammers you won't be able to work much more than 6 inches of hot steel before it needs to go back in the forge. If you are working with high carbon steel especially then the repeated heating can have a detrimental effect. It effectively lowers the carbon content in the steel. On the other hand if you have a power hammer or you are doing long decorative twists that require long sections to be heated then a larger forge may make more sense. From personal experience and from what I've seen from most people on here, the tendency is to build a larger forge than necessary with the mindset of "better to have it and not need it" than the other way around. I had that at first too. Now I want a gas forge as small as I can get away with. The nice thing about brick pile forges is that you can rearrange the bricks to get different shapes and sizes fairly easily, so you can experiment a bit to see what works best for you.

You can still make it wider than tall fairly easily. Soft firebrick is easy to cut with a dull hacksaw blade or something similar. So, you just need to create a small shelf in your vertical bricks for the horizontal bricks to rest on. If you cut a half inch off the thickness of each of your vertical bricks on both ends to a depth equal to the thickness of the bricks then you won't have to worry about the bricks falling in and you'll only lose 1 inch off the width. By using all thread and angle iron you should be able to keep everything together nicely. Hope that made sense. If not let me know and I'll try to sketch something out for you.

It would be helpful if you included your location in your profile. Since this forum has members from all over the world, an answer that might apply in the US may not apply to someone in Belgium or South Africa. Next we need to get an idea of what you want to do. It looks like general knife making based on your post, but if there are other things we need to take into account that could affect the answers you get. Then we need to know what you are willing/able to spend. After that we need to get an idea of what resources you already have or have cheap/easy access to. If you are relatively handy with (and have) basic shop tools you can build your own grinder. If your junk resource pile has some square tubing around 1.5" to 2" and you have a working TEFC motor that's at least 1 hp you can put something together with only a little more than your own labor and a wheel set. If you have to buy new steel and a motor that will make a difference of several hundred dollars US. If you can give us a little more info we'll try to get you pointed in the right direction. If you do not want to build one yourself, and don't have the funds for a grinder that has at least a 1.5 hp motor, then I'd suggest using files and saving up for a decent grinder. You will learn a lot by hand filing and that will actually be beneficial to you when you transition to a grinder. Hand filing will also encourage you forge close to your final shape so you don't have to spend as much time with the files.

All the above is good advice/information. I'll add one more thing. If you continue to try to forge when the steel has cooled too much, it's easy to introduce cracks. The next question is, of course, what is too cool? The answer is it depends on the alloy. Generally speaking though, you want to quit hitting with blows that change the shape before it drops into the dull red range. You can still do light blows for straightening safely (usually) at that heat, but for moving metal generally you want to be in the orange range. Again, this is alloy dependent. For mystery metal you will need to do some experimentation as mentioned above.

FWIW, I don't see a justification for the response you were getting here ironjohn. You're trying something new (to you anyway). You seem to have narrowed down what you believe to be the problem area and are attempting to deal with it. From what I could see you have molten glass in your crucible, which should go a long way towards controlling the atmosphere the steel is exposed to. Dunno. I follow the wootz discussions on here whenever I see them, but have never attempted it myself. I guess I'm just saying I hope you continue with your experiments and post the results be they good or bad.

Frosty, Sorry to butt in here, but... what are you seeing that leads you to a diagnosis of a rich flame? At first glance I thought it looked pretty good. I do see multiple flame envelopes, but not the colors I'd normally associate with a rich flame. What did I miss?

As satisfying as that is to you, you have no idea how satisfying it is to us to have someone listen to the advice given and experience the success that follows. Thanks for the update.

One of the challenges starting out in any new field is learning the lingo. We have to make sure we're talking about the same things in order to troubleshoot and give advice. That's why you'll see some people seem nit-picky over terms. It can be confusing enough even when we're all on the same page, but when we're not it's darn near impossible to have a productive discussion. Obviously if the designer recommends a part change from his original plans you go with that. Likewise if he writes anything here that contradicts something I've written you should always assume he's right and I'm wrong. There could be a slight chance it goes the other way, but the smart money will bet on Mikey.

If you've gotten Mike's book you are on the right track. As said before though, do not attempt to use components other than those specified. Despite these burners being DIY, there is a fair amount of precision needed for them to function correctly. Something that is "close" may end up making the burner significantly less efficient or possibly non-functional. As for the flame burning in the flare-- they are supposed to do that. There should be no flames inside the mixing tube, but there will be at the end of the mixing tube inside the flare. The flare is a consumable item that will have to be replaced from time to time. It will become oxidized over time and deteriorate - even stainless steel.

There are several potential reasons for what you are experiencing. You'll have to do some troubleshooting to narrow down the cause. However, I'll give you the 3 most likely reasons (in my opinion) that this could be happening. 1. Too much air being drawn in compared to the fuel. It's hard to keep a really lean flame lit without it blowing off the end of the burner. 2. Axial alignment of the mig tip inside the mixing tube. If the fuel stream is not centered in the mixing tube the burner will not function correctly. 3. Debris in the jet orifice restricting the fuel flow. You did not mention where you had the choke set or if you changed it when experiencing this problem. Try choking off most of the air to see if you can get a stable flame. If you do and the flame is blue-greenish then open the choke a bit more until it turns a medium blue color. Moving to a .020 tip would only make the situation worse. If you constructed the burner correctly and you have centered the mig tip properly then the prescribed mig tip size should work. If anything you'd want to move up in mig tip diameter, but again if you made it correctly that should not be necessary. I guess I should have started with this: Hopefully you constructed the burner exactly as described by Mr. Porter in his book. Deviation in dimensions or parts almost always results in negative effects on burner performance. Mike checks in here on a regular basis, and in theory you made a burner based on his design, so he should be able to help you sort this out.

A lot of those types of bricks can withstand the heat, but they do not insulate well. That means a fair amount of wasted heat and fuel. We want the heat to go into our stock as much as possible, not the forge lining or out into open air. What you want are insulating firebricks. Look for something like Morgan K26 bricks. They are significantly more expensive and fragile than the bricks you used, but they keep the heat where we want it far better.

You're not wrong to focus on the burner, but I do have to ask for one point of clarification. It appears to me that you are using hard fireplace type bricks rather than the soft lightweight insulating fire bricks. If that is the case you will experience a significantly longer heat up time for the forge, and you'll lose a lot more heat through the bricks themselves. It sounds like your burners do need some attention, but to get a properly functioning forge all the components need to be right - or as close to right as you can get.

Are you trying to use a naturally aspirated burner or a forced air burner? Household appliances that use LP normally run on very low pressure. Naturally aspirated burners require higher pressure. A max of 12 psi would be lower than I'd like for a NA burner. Some systems also have flow limiters installed. A regulator will restrict the maximum pressure, and a flow limiter will restrict the volume of gas per minute. Some will completely shut off the gas if the flow is higher than the setting on the limiter. That's a safety feature to stop the gas in the event of a supply line break inside the house. Attempting to use too much gas too quickly can simulate a leak and trigger these. I'm not saying that's what's happening to you, but there is a possibility it could be involved. I use propane for my hot water heater and furnace. There is a regulator just outside the house, but it was there when I bought the house and I've never attempted to change the setting. In theory you should be able to use a forced air burner with low pressure as long as it allows enough volume to flow. The gas company owns my tank so I've never tinkered with the fittings, even though I've been tempted to for the same reason as you. If you own the tank AND local/state laws allow, you could potentially run another line directly from the tank to your forge. If you do, I'd suggest installing a regulator at the tank itself to limit the line pressure to something like 30 psi and then another regulator at the forge to control the burner performance.

For me the starting point is determining the intended use of the forge. Is this for general forging? Decorative twists on long stock? Knowing the intended use can help with determining whether you need to avoid hot spots or if they could be beneficial, for instance. That can affect burner placement and aim. Very generally speaking, to me that is a longer forge than I would suggest for typical use. It can be a bit tricky to get the placement and aim optimized. We want to keep as much heat in the forge for as long as we reasonably can, so from that point of view it's best to not have the burners so close to the ends that a lot of the heat escapes before we use it. On the other hand if you want even heat throughout the forge you have to install them close enough to the ends to avoid significant lower temps at the openings. To make things even more complicated, especially for naturally aspirated single port burners, the flames from one burner can interfere with the performance of another burner. Naturally, this tends to happen the closer the burners are to each other. On top of all that, no two DIY forges are exactly the same. The final shape of the forge chamber affects flame swirl and how exhaust gases escape the forge. Once again, that can have some impact on how well your burners function and where they should be aimed for best performance. All of that to say this: If you are set on building a forge that size using 3 burners, then the general guidelines for spacing you show above are a good starting point. However, it would be best to build it so you have some flexibility with where the burners are aimed at the very least. If you are using naturally aspirated burners, the more burners you install the more chance there is for them to interfere with each other's performance - either on the intake side or the flame side. If you are using forced air this is much less of an issue. I'm a big fan of the naturally aspirated ribbon burners (NARBs), so if I were doing this project I'd probably use 2 of them evenly spaced between the center and the ends of the forge, and I'd probably mount them on the side of the forge near the top so that the flames would swirl around to the floor. My preferences may not be what's best for you though.

Yes, you can try again. If it's not hardenable steel it won't make much difference. If it does have enough carbon to harden then you may want to try progressively faster quench methods. However, if it requires something like a brine quench or superquench to harden, then it really isn't good stock for a knife. Without knowing what quench mediums you have access to it's hard for me to suggest a sequence. You want to make sure the portion you are quenching is above critical at the time of quenching, and if possible you want the same temperature on every quench. If it were me I'd try a heated oil quench first. If that portion did not appear to harden I might raise the steel temperature a little bit and try again. If it still didn't harden I'd go to water. If it doesn't harden at that point you can disregard their claim that it is high carbon steel and not waste your time making a blade from the rasp. If it hardens in water but not in heated oil I'd be thinking it is probably a medium carbon steel at best - and still not a great choice for a blade. If you are familiar with spark testing you can probably get some idea of the carbon content that way as well.

I'm not sure how much benefit there will be to that set up, but it looks functional. I believe Frosty has mentioned in other threads that in a gas forge we are heating the interior surface which then radiates the heat back into the forge to heat up the stock. Generally speaking you don't really want the flames to impinge on the stock directly. If you go through with a full scale build let us know how it turns out. Every once in a while someone's new idea changes the game.

A galvanized trash can should be ok. The only real danger posed by galvanized containers would be if you happened to somehow get the zinc hot enough to oxidize. Then you could end up with fumes it would be best not to breathe. If you are wanting to go the extra step with safety, you should create what is essentially a container within a container, both with their own lids. When we quench, sometimes the rapidly expanding oil will end up splashing outside the quench container. Hot oil is fairly flammable, so you can imagine what happens if oil is on fire and running away from your quench tank. However, if your quench tank is inside a larger container with a lid then you can just put the lid on to snuff the flames and everything is contained safely. Having it outside limits the likelihood of catching something else on fire of course, but even leaves or other flammable debris can be an issue. As far as heating the oil goes, the answer is "it depends." Some quenching oils do not require warming. If you are using something like peanut oil or canola oil then you will probably want to warm those up before quenching. Somewhere around 120 to 130 F is usually suitable for those types of oils. What you are trying to accomplish is a low enough viscosity for the quenchant to remain in contact with the hot steel as much as possible during the quench. You'll get the best results from doing exactly the same thing every time once you dial in what works for you with a given alloy, but generally speaking you can warm the oil by dunking a hot piece of metal in it and stirring. You don't need some fancy and expensive device - especially not for simple alloys when you are beginning.

I haven't weighed it, but I estimate the tup weight around 35 lbs. The hammer sits on a standard garage floor. The detached garage was already built when I bought the property so I don't actually know the concrete thickness, but I'd guess it's roughly 4 inches thick. My hammer is mobile and I can move it out of the way when not in use. The base plate is 4" thick and 20" by 24", so the base weighs around 500 lbs by itself. The anvil is another 250-300 lbs. That probably helps a bit with the stability, but I did install outrigger supports to limit the swaying and walking that happen at certain RPM.

Thanks for posting that. I have one of those machines and have had difficulty getting long square cuts at times. Of course you can get a blade sharper on one side than the other or the guide bearings out of adjustment, but it's good to know there may be another relatively easy thing to correct.

I concur with this. I glued 2 inches of plywood under the base of my hammer. I believe it does relieve some of the impact stress on the concrete below, but there doesn't seem to be an appreciable amount of noise dampening.

How long are you willing to wait for it to dry, and/or how do you intend to aid the drying process? If you are willing to wait months or years, then you can seal the cut ends with wax or something similar and just leave it inside somewhere relatively dry. If you don't seal the ends it's more likely to dry faster at the ends and start to split the wood as it dries. Knife scales are rarely thicker than 3/8" each and are normally under 6" long, so usually you can salvage scales from a piece of wood 6" or so in diameter even if has begun to split on the ends. I've never used any "assisted drying" techniques, so I'll leave that to someone else with experience in that area. One other note: the first set of scales I made was from a walnut tree in my back yard. I selected a piece with no knots, twists or any other "blemishes" and it was decidedly..... boring. I would recommend trying to find a piece of wood with some "character" to make the handle interesting, but to each his own. I have no experience with crabapple for this application, but it seems to me that it's hard to find a piece of that wood without some character to it.

Not sure this would work for you, but I used the top part of RR track for my dies. Of course it's a bit of work to cut the webbing, but for me it was a suitable option. Looks like you're going with bigger dies than I used though.