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Jeff Amundson

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Jeff Amundson last won the day on August 23 2023

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  1. Trying a new supply of wrought iron. It's the most steel-like WI I have seen. It came from a chain with links made of 3/4" rod. I had to etch it to confirm it was WI. I couldn't get it to split in the first tests. These are steeled with 1075.
  2. Thanks for the compliments. What might appear to be skill or talent might be better described as persistence.
  3. I've been playing with bronze metal clay for the finger bows on scissors. I'm trying to find an easy way to shape and polish the inside of the bows. After several false starts, I finished this pair. I chose wrought iron because I couldn't resist combining 13th century blades with 20th century bows. As discussed before on this forum, most metal clay is used for jewelry, not structural pieces. I chose a version called sculptor's bronze with a shrinkage rate of 9-14%. I took several measurements before and after firing. The shrink rate wasn't consistent within the part. For example, the bows shrank more top to bottom than side to side. However, the shrink was consistent from one part to the next. The pair went into the oven nearly identical, and they came out that way. Metal clay is water soluble, so joining two pieces together was a bit like welding with water. I chamfered the ends of two pieces of clay like I would with a metal weld. I then thinned the clay so I could drip it into the joint with a toothpick. For the subsequent passes I would make the clay a little thicker each time. Because of the shaping and sanding I did in the greenware state, after firing I was able to polish the inner surfaces of the bows with rubber polishing bobs. That's enough success to motivate me to try again.
  4. Yes, congratulations. I'm glad you're thinking about doing it again. The advice I have is to taper the back end of the 1075. This shows the taper I grind in both width and thickness. This is 1075 welded to 1018. Without the taper, the 1075 acts like a shear and cuts into the softer 1018. After I set the weld, blending in the tapered end is my first priority. It can take multiple heats because it cools so quickly.
  5. I've discovered that many left-handers struggle to use left-hand scissors. They have learned how to twist their left hand to use right-hand scissors. When presented with left scissors, they hand it back to me saying it won't cut. It's happened to me multiple times. I have to show them the correct way. And manufacturers are making left-handled scissors that put left-hand bows on right-hand scissors.
  6. More than once I have given left-handed scissors to left-handed people who hand them back saying they don't work. Many left-handed people are conditioned to contorting their hands to make right-handed scissors work. To accommodate that population, manufacturers are making left-handled scissors, which have plastic handles fit for the left hand mounted on right-handed blades.
  7. Welcome to the world of scissors, AlexDB. As you discovered, the internet isn't very helpful, so I'm happy that we'll make the internet a little smarter with this thread. I read somewhere, probably something Grace wrote, that "we're not making blades, we're making springs". Obviously that refers to the flex required to keep the two edges in contact, but it also suggests hardness isn't maximized. I think Grace aims for hardness in the mid-50s. I think you should choose an alloy that you can successfully heat treat to medium hardness. Your second question is more complicated. I don't like to use the word 'tension' to describe the force the blades put on each other. The ghosts of the engineers I've worked with won't let me, so instead I'll talk about the force required to open and close the scissors. An engineer who helped design plastic finger bows for Fiskars told me that our hands are much weaker opening than closing. Ever since then I try to adjust my scissors so they open as easily as possible. If you open most scissors so the blades are at 90* to each other, you'll find the pivot screws are not holding the blades tight to each other and the blades can wobble a little. When you start to close the scissors, the anatomy of your hand forces the two blades together. Your thumb pushes away and your fingers pull in, which is just what the scissors need to force the blades together. That only works for the first inch or two of blade, so the blades are bent to keep some force on the blades all the way to the tip. When I assemble a pair, the blades are flat on the inside, no bend. I adjust the pivot screw to what feels right, then Iock it by peening the threaded end. I only need the threads to make fine adjustments. After that it becomes a rivet. I put a decorative head on my homemade screws so people aren't tempted to adjust them. Once the pivot screw is set, I start making test cuts using the thin plastic produce bags from the grocery store. I bend the blades only as much as needed to make full clean cuts in the bags with little effort. Sometimes that process leaves a pair that seems too loose, but it passes my test just fine. They get handed back to me frequently by people who say they're "too loose" without even trying them. They cut just fine. I think another factor at play is sharpness. Dull blades require more force to keep material from passing between the blades. It seems reasonable to think sharp blades require less force. I can understand why the mild steel didn't work for your tests. It probably bends too easily. Here are a couple other factors to consider. Tin snips are about as long as your blades, but they have no bend in them. They're flat on the inside. Is it just their stiffness that makes that work? The blades in this post are not bent. They are angled relative to each other, so the tips cross, but the blades themselves are flat on the inside. This doesn't work in a pivoted scissors, because it would be too tight, bent in a straight line from pivot to tip.
  8. Yes, you missed it. I start with 1018, then I weld 1075 to it. On the inside, it's flat first, then a hollow is ground, leaving only a tiny bit of flat left at the cutting edge. These are all about 7 1/2" overall, 3 1/4" - 3 1/2" cutting edge. Thanks, Dick. There are little blobs of clay propping up some of the blades to eliminate the glare.
  9. Thanks @Charles dP. Both the smith and the bonsai specialist have aged from these earlier videos. https://www.youtube.com/watch?v=6CdmgXUa6d8 https://www.youtube.com/watch?v=TD2XGwmRJi8 I do most of my bending hot. Bending cold can lead to smoother curves, but good technique is required for both. He might be doing it cold because he doesn't want to heat up the handles he just filed smooth.
  10. This is a few years old (before scissors). The cherry wood is nicely aged. The knives are 1084. I wanted a small twist, so it's only 270 degrees. That means the blade and handle were forged flat in the same plane. The blade and handle are rectangular in cross-section. The transition from blade to handle is square, which is where the twist is. The handles have a nice flex. The rack has 1/8" thick magnets that hold the knives in place. I drilled holes through 1/8" thick aircraft plywood to hold the magnets. Then I covered one side with cherry veneer. A bonus - the magnets also hold everything on the side of the refrigerator.
  11. Thank you very much for all the compliments. Yes, they cut. I'm a toolmaker. My previous post explains how I test them. https://www.bladesmithsforum.com/index.php?/topic/42842-forging-scissors-photos-of-my-current-process/ Thanks for asking. This seems to be the mystique of scissors making. In my learning, I looked at the shearing action of many tools, including tin snips and foot operated shears. It's helpful if the shearing blades are sharp, but it's critical that nothing passes between them. For scissors, human anatomy forces the two blades together naturally. As your hand closes, the fingers pull and the thumb pushes. This is only effective for the first couple inches as a scissors closes, so a slight curvature (yaw, as opposed to pitch or roll) in the blades is necessary to maintain that force all the way to the tip of the blades.
  12. I went into production mode with these two designs. The process and tooling are the same for both, so I was able to focus on process refinements. I processed them in batches of 2, meaning 4 blades welded and forged, ready for heat treat before I'd start another batch. By having blades at various stages, the bottlenecks show up fast. It turns out the hot work is about 25% of the total time to make a pair.
  13. This scissors is rust blued wrought iron, sitting on the bar it came from. I probably etched it in ferric before bluing. The parts get boiled to blacken the rust, so I don't know if it qualifies as cold bluing.
  14. Thanks again, Alan. I wasn't trying to discount this work with that comment as much as anticipate better things to come.
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