Buzzkill

If I understood correctly, a key factor is the alloy having a unique composition that indicates it could have only originated in one place. All 2square is requesting is a plausible (even if unlikely) set of circumstances in Belgrade in 1944 in which the gold was contaminated by other alloying elements in such a way that there can be no doubt as to its origin later in the story. To me, the brass/bronze foundry scenario posed by George seems the most plausible way to achieve the desired result here.

Ultimately the purpose of quenching is to remove heat from the steel at a rate suitable for that steel. Depending on the alloy, that could be anything from air cooled to brine. The method of cooling is not as important as cooling at the correct rate for the alloy. The reason I bring this up is that no quench medium is "best" in all cases. The guys at Knife Steel Nerds are very knowledgeable, but keep in mind they are attempting to squeeze the absolute best performance out of any alloy they test. No, canola oil is not the best quench medium. However, that oil, peanut oil, mineral oil, automatic transmission fluid, etc. may be suitable for your needs if a more suitable quenchant is either not available to you or cost prohibitive. This is where you may have to get creative. If you have an alloy you will be working with repeatedly then you can make nearly identical test coupons to quench in different mediums and test to see if they provide the results you are looking for. This can be a bit tedious, but if you are methodical and take good notes you can figure out what works the best for you overall in your situation. Of course it gets a bit more involved when you take into account both the quenchant and the tempering temperature. Although I don't recommend it based on information I learned after starting, I have quenched in used motor oil. I've also used automatic transmission fluid. For alloys needing a medium speed quench those can work out well, but probably not quite as well as a formulation specifically designed as a medium speed quench oil. Don't let the drive for perfection keep you from doing something that is still quite good.

There was a bit of a learning curve to the whole thing, and it was further from "square and flat" than I thought. I had to adjust the depth at least 3 times on each side. The bit wasn't touching in some places, but was removing around 1/16" (guesstimated) in other spots. I should have said the bit was 1/4" wide and each pass was about 1/2 of the bit width, so double the passes where there was material to remove. Like I said, I can't really recommend it, but I know I can make it work when I need to.

It was a slow process. It took a while to get the block leveled satisfactorily and then install and level the rails. Of course I had to build the sled for the router too. Working a surface more than 5 inches square a quarter inch at a time is a little tedious as well. Still, it's far better than I could have eyeballed, and I'm comfortable it's good enough for dies on the top and welding to steel plate on the bottom. The bleeding was minor. I got a couple steel splinters, but that seems almost inevitable for that kind of work. The blood could be measured in droplets, so I'll consider it a win as well.

Nope. I was just gathering information at that stage. Ultimately I went with the router/carbide bit plan. I can't say I recommend it, but it did work - although I did pretty much destroy the carbide bit by the time I got the second surface finished. Now it's on to designing, fabricating, and installing the die holder for the anvil.

I have not found a reliable "rule of thumb" for the ratio of the area of mixing tube to the combined area of the nozzlettes. My conclusion is that there are too many variables to come up with a reliable guesstimate for a starting point. The diameter and length of the the individual holes will definitely play a part, as will the material of the burner and the relative smoothness of the the interior of the holes. I have not found a better way than Frosty's approach. Use a block of wood if you can and start with more holes than you think you need. Block off holes until you stop getting burn back into the plenum at low to moderate pressure. Make another block with that number of holes of the same diameter and test again. If that one comes back with little to no flame lift off the face and no burn back into the plenum you should be set for casting. That's for a naturally aspirated burner. If you are running forced air there is more flexibility to err on the side of too few holes without seriously negatively affecting the performance of the burner. Having too many holes will limit your turn down range in both cases. However, holes can be plugged easier than adding new ones.

Been there, done that. If you actually click on them you'll find that most of them take you to cup wheels designed for masonry. However, it looks like there are some called "flaring cup grinding wheels" that do indeed appear to be designed for metals. Rather pricey though. I'm still wondering if the cup wheels designed for masonry are effective if used on steel. I've used masonry cut off wheels on steel before and they don't work as well as those designed for steel, but they suffice in a pinch.

The only cup wheels I found seem to be for masonry type of work. Are those suitable for steel or is there another type of cup wheel that I overlooked?

anvil, George, and everyone else I appreciate you voicing your opinions and concerns - that's exactly what I asked for. If I use the router it will not be free-hand. I will build a frame and sled mechanism from square tubing and/or angle iron to keep it square to the sides and limit motion in all directions except traversing the face of the block in a straight line. If I use this method I will also use a rheostat controller to decrease the spindle speed. I think overall it would be faster/more efficient to use a grinder and square to get close then draw file. I don't need precision measured in ten thousandths of an inch. However, I see this as an opportunity to try something that may have applications for other projects in the future.

Well, the nice thing about this for me is I have the router already (found it last night). I bought it cheap with other tools at an auction, and I haven't needed it for anything else in the past couple years. So, if the plan doesn't work or I destroy the router I'm really not out more than the carbide bits. If that happens I can still go to plan B or C which involves some combination of angle grinders, files, levels, and squares. I'll try to remember to report back here how it goes, but I probably won't get a chance to do anything more before the weekend - and even then it's a maybe thing.

My tempering oven isn't pretty, but I took the guts out of an old toaster oven and I also use a PID controller. The only reason I took it apart is the interior dimensions were too small for some of my larger blades. However, since I know I'll never have the oven over 600 degrees F, I chose to use rockwool insulation that is rated for up to 1200 F, and it's sandwiched between two layers of sheet metal. Originally I thought I'd use the heat treat oven I built a few years ago to attain quench temperatures and then temper afterwards, but it takes quite a few hours to cool back down to tempering temperatures after being up around 1500 F. I can't run them both on the same circuit at the same time without tripping a breaker though.

I'm leaning towards the router idea if I can find the router. I think I bought one at an auction a few years ago. It's doubtful that I could "gently" lower this block straight up and down on anything at this point. I know I can't do it myself - even if I lift with the legs.

Just don't tell my boss. I'd hate to have to fire myself.

Agreed. I'm just trying to figure out if it actually is reckless. Generally speaking, if the blanket is contained between 2 metal sheets and not directly exposed to the working area would you consider that appropriately sealed off? I would cautiously answer that it is. I'm not trying to pick a fight with anyone or even really pick a side. I do think we should err on the side of caution, but I also think we should be realistic or at least avoid being alarmist if it is not truly appropriate.

Thanks for the suggestions so far guys. The tinkerer in me wants to build a sled system for a power tool, but the practical side of me is arguing that it's only 2 ends about 5.5" square. I probably won't get a chance to get back to it before the weekend anyway, but it gives me something to think about in the meantime.

I think I picked up a router somewhere along the line, but I'm sure I don't have any carbide bits. That still may be the best bet. Surprisingly, or maybe not, I was noodling with an idea to build a frame to hold the angle grinder at a consistent depth. Sounds like roughly the same idea, but using a router instead. I'm assuming I set up the sled by using a level/square combination to make sure the router rides on rails that are as perfectly perpendicular to the sides as possible. I'm thinking an angle iron framework with some adjustment screws in the corners. Is there a better way to accomplish that?

.Darn it, Frosty! You can't do this to me at work. I gotta fake being sick when I sniffle while reading that stuff.

I'm in the process of rebuilding my tire power hammer. I acquired several pieces of 3/4" thick steel, which I have fastened together using full perimeter welds. I now have a more or less solid chunk of steel to use for my anvil that is 5.5" x 5.25" x 29.5". I need to clean up the ends that will be the mating surfaces for welding to the steel plate on the bottom and support bottom dies at the top. I'm looking for suggestions to help me get flat surfaces on the ends that are square to the sides. I do not have any milling equipment or anything else that can handle a nearly 250 pound chunk of steel. Left to my own devices I'd probably end up using a 4.5" angle grinder, a carpenter's square, and copious amounts of verbal "encouragement" to get the result I'm looking for. Any and all viable suggestions are welcome.

Hmm. A heat treating oven would not be reaching very high temperatures for kaowool. If the blanket is not exposed it would be far different than direct flame impingement in a gas forge. If I understood correctly, he took the cover off, wrapped the inner compartment with wool (on 3 sides) then reinstalled the outer cover. To err on the side of safety we would certainly recommend a rigidizer/sealant, but this seems like a low risk situation to me. There would be more potential for airborne fibers during the installation than during use it would seem. Still, better safe than sorry.

Looks like West System has a slow hardener (206) to go with their resin (105). They also have an extra slow hardener (209).

Jono, it certainly can get messy. You must have planned properly before starting. That makes a huge difference. It's easy to go into panic mode once you've mixed the fiberglass resin if you don't have everything set up to quickly add all the layers. To me it looks like you nailed it. What I like most about micarta is the fact that it is so durable. It doesn't care about water. It can withstand heat higher than you can hold in your hand. Yet, it's relatively easy to shape and sand.

Thanks PB. I checked out a couple of those vids. Good stuff, and the induction machines are getting down into affordable territory now. I may have to rob my firearm fund and get me one.

Are you forge welding using induction? This is something that interests me a lot if it's possible.

High carbon billets weld well with my NARB powered forge. As Frosty indicated, prep is key. Every mating surface has a fresh shiny grind, and the layers have uniform dimensions. I don't use flux - just a dip in oil before heating. I haven't tried to forge weld low carbon or irregularly shaped stock, but I'm pretty sure I could do it - especially if I used flux.

Way too much. By my calculations you'd need 4 of them for the size of forge you have planned. What you have described is a gas guzzling monster of a forge. Unless you are planning to do production work where several people will need to be heating things in the forge simultaneously or you have a very specific need for a forge chamber that large you should seriously consider a forge with a smaller chamber. Just because you have something you think would make a good outer shell does not mean you have to use it - or all of it anyway. Everyone has their own preference depending on what they do, but for reference's sake my current forge chamber is about 23cm wide, 10 cm high at the apex (it's roughly half a cylinder), and around 20 cm long. That's about one fifth the volume of the forge chamber you're planning to build, and your plan is about 3 times the volume that Simian is using 2 burners on. It's hard to have too much insulation from a functional point of view. However, there is cost associated with it. The conventional wisdom is that 2 layers of 1 inch thick each is the point at which we get the most benefit for our money. If you're just trying to decrease the internal volume of the forge chamber, you can add extra layers or possibly even use rockwool insulation for the outer layers and save the ceramic blanket for the inner 2 inches. You can also consider using something else for your outer shell. It doesn't need to be particularly robust. The main functions are to keep the ceramic blanket contained, and to keep it from being damaged. I've used sheet metal thin enough to be flexible for the outer shell on a couple forges and that's worked fine. You can build brackets from angle iron or other stock to support your burners/mixing tubes. I agree with Simian. For a gas forge it's better to build the smallest forge chamber that will still allow you to do what you want to do. That will save you money on the initial construction, but will save you a LOT of money in fuel in the long run.