Andrew Golabek

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Everything posted by Andrew Golabek

  1. It is definitely not because of the incorrect forging temperatures, but rather the high alloy content
  2. I’m going to either remelt this one and add some mild steel as the carbon content seems too high (it starts to crumble quite easily) or just start from other materials, as the hardness at temp is very high. Other options are; make some new tongs and be very patient forging it out ( I don’t have a press/power hammer) i was attempting to hot cut it in half, and a corner just came off.
  3. When I start forging it into a billet should I forge it making the top and bottom the ends of the billet, or should I forge it from the sides? I was thinking from the sides since it has one side which is not very smooth due to a piece of trapped charcoal and if one way is preferable, why?
  4. I spark tested it today, and polished up the bottom face to check if there is any visible porosity. Unfortunately my camera didn’t focus well during the spark test, but I’ll describe it; The sparks were dark red, and very short without any visible branching. I compared it to o1, and mild steel which both sparked xxxxxxx a lot more. Then compared to a high speed steel drill bit, which had quite similar sparks however the crucible steel had slightly shorter ones, and less. current thoughts are; due to the saw blades and drill bits used to make the steel, and the other scrap metal/forge scale, it has a relatively high tungsten and molybdenum content, and a medium carbon content. Perhaps the carbon content is slightly low but I’m not sure since it was mostly high carbon steel as input and it was melted under reducing conditions the whole time with a thick layer of charcoal covering, and glass.
  5. Today I was successful at melting down some old bandsaw blades, and drill bits along with some old pieces from knife testing, in my propane furnace! Got a small lump of steel, have yet to check it in anyway for carbon, but this is the first step! Any suggestions on how to proceed? Keep in mind I do not have a forging press or power hammer.
  6. I didn’t use a degasser, I followed some of the recommendations in the ASTM copper alloys handbook for casting bronze alloys with tin. Some of the most important things I make sure of -the sand must have the proper moisture content, just enough to lend the mold strength, but not enough to cause water and subsequent hydrogen and oxygen porosity -I use ground charcoal for deoxygenation, you can’t add too much. -better results may be obtained if it is the second time melting a piece of freshly alloyed metal (the first time from many small pieces seems to have more porosity) not sure if this is 100% true, but it might be. -cast quite hot, I think around 1100c, when you touch the surface of the bronze it should be shiny and very liquid not viscous and not with an oxide layer. This is very key to casting thin items. -I’ve also tried degassing with a green stick of pine. Not sure how this works but the handbook mentions it and it seems to work. -sprue and gate must be properly formed, follow the guidelines in the handbook, later I can update the exact measurements of mine. Here’s a picture of one mold half. 75 grit silica with 10% bentonite looking to get some 125-150 grit to add in as well for next casting
  7. My latest knife has 13% tin, and 0.1% I think of zirconium added. The zirconium is a grain refiner for this type of copper alloy, and also increases hardness. my casting process has also improved quite a bit, there is zero visible porosity on the last knife.
  8. That last nozzle reminds me of one used for flame emission spectroscopy
  9. I think you are underestimating the material, it is hard enough that it won’t roll that far back unless it was exceedingly thin
  10. I took a few passes along the blade, the total width of the hardened area is approx 5mm I think, past that point I don’t think there is much benefit as the hardness of the cutting edge is what makes the largest performance improvement
  11. Yeah, i measured the density of the bronze as I cast it, to help me get an idea of the amount to melt for the casting, it was approx 8.7g/cm3 which is quite higher than steel between 7.7-8g/cm cubed. Testing recently revealed I didn't harden the edges sufficiently as it rolled in one spot, so I made a better jig for hammering them, and now it is much better. I'll attach a picture once I take some
  12. So far, my foundry has survived in nearly the same shape as it was when i started aside from some discolouration due to some silly experiments. I've successfully cast about 10 items so far ranging from 1lb to 4lb melts of classic bronze. The highest verified temperature I've achieved was approx 1400c during some experiments with ceramic it survived perfectly intact, which isn't a large surprise given the max temp rating of 3200f. Now onto its downfalls. There is a lot of larger grit in this refractory, no doubt giving extra strength, but mixing, and casting it without too much water by hand can be difficult. I couldn't find instructions for it online in regards to curing or water content, so just went with what seemed appropriate, as you add water to it, at a certain point it will become much easier to mix, and if there is any vibration it will act liquid. I think that is the ideal amount. Any higher, and from what I was told by the foundry supply is that it may not come out as strong. It sets like cement in approx 24 hours. The surface finish can vary depending on how well it was done from glassy smooth to very gritty with air bubbles on the surface. Firing it can be done relatively quickly once it has been dried with a low flame.
  13. It seems that lead was deliberately added in the past to help the castings flow better into narrow sections. tin had to be mined separately and it was alloyed to make the classic bronze
  14. Search up Neil Burridge, I believe he does the closest work to ancient methods, for European bronze replicas. Swords are cast, cleaned up, annealed, edges are cold forged, and the spine is hardened by hammering, and some bending. One problem with many of the ancient bronze alloys is the lead that was commonly added makes it hot-short.
  15. We have some proper cameras and equipment at home, these pictures were simply casual ones.
  16. Not home right now but I did take a picture with a less distracting background before; when I get home I’ll take some proper pictures.
  17. Nearly done, only final polish for the handle and oiling is left. brought it to the forest to test chop some bushes and stuff, works pretty well, I’m going to make a video in a little while showing what it can do. -the weight is 1.23kg or 2.71 lbs -the point of balance is 5.25 inches from the guard now or 13.3cm. -maximum width of the blade is 43mm.
  18. The blade has been final work hardened, ground, and polished. The handle has been rough shaped, almost ready for final shaping and sanding, then oiling
  19. Done most of the grinding, putting the handle on now, also work hardened the edges and annealed it prior to work hardening
  20. It looks to me like the burner is running way too rich, (even outside the forge) and the mounting tube is too long, preventing adequate airflow to the burner, increasing the problem when mounted in the forge Also be sure to rigidize the ceramic blanket if not done already
  21. I suppose for this casting it served as double duty, as both sprue and gate at the end of it i don’t have any methods currently to turn it into other parts so it will probably just be used in the next melt
  22. Did some grinding today; break down of the casting -sprue weighed 523g -tip thing I made weighed 36g -sword weighed approx 1250g once cleaned off as of this picture it weighs 1151g (2.53lbs) balance point is about 5.75 inches forward of the guard going to lighten it up at the front some more, handle is planned to be made of bubinga wood
  23. It will be work hardened, and I’m still not sure if it will be annealed or not before, it is quite stiff already, and some pieces I cast beforehand were slightly brittle, although perhaps brittle is an exaggeration as they were beat on with a sledgehammer haha the bronze knives I’ve made so far we’re cast, and then the edges were work hardened, no annealing was done at all.
  24. The mold is made from greensand, in an oak flask I made, with the particle board faces so the sand doesn’t crack outwards. Greensand mix was 75grit silica, 10% western bentonite, I’m guessing it was about 70-80lbs to fill the flask!! The foundry is propane fired, I used a graphite crucible, and the only flux was charcoal, both powdered and in chunk form (charcoal was made in the foundry prior in a heavily reducing atmosphere) i used a wooden pattern that I ground out on a bench belt grinder. this is my sixth bronze blade, although it’s about 4 times larger than anything I’ve cast before haha, I’m planning on grinding it smooth, and then annealing the spine with the propane torch (undecided whether or not to anneal yet), and then I have a little jig I use to harden the edges whether or not it will kill remains to be seen haha, definitely planning on testing it once it’s done, perhaps a chicken is on the order