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Brian Dougherty

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Everything posted by Brian Dougherty

  1. Stress concentrations are a very real engineering concern, but as you say, it is nearly impossible to make a perfectly sharp inside corner. For knifemakers, the question becomes, "How much of a radius is necessary for a knife to do its job?" I'm a sparkey so I didn't take that many mechanical engineering classes, and the last one I had was darn near 30 years ago. Take the following with a truck-load of salt. The stress concentration factor is a function of the geometry of the joint. The fillet required on a large notch needs to have a larger radius than on a small no
  2. Looking good. If you are really feeling guilty, and need someone to send it to, I'll volunteer
  3. Looking good Rob. Amazingly straight to my eyes! As I visualize (fantasize?) the quench operation on long blades, one thing that seems like it will be difficult is the transition from horizontal to vertical without letting the balde bend under its own weight. I assume you grabbed the tang with some tongs and supported the middle with a stick somehow? How did it go?
  4. Thanks Jerrod. I've come back and read through this a few times with some time in between to digest. I've been tempering 1075 folder springs at 550F. I haven't seen any break (yet) and am now wondering if it is just luck, or if it is because the 1075 I have is clean enough to not fall into the "one step temper embrittlement" trap. The max S is 0.05% and max P is 0.04%, but as you say, the mill probably tries to run below that. What do you think?
  5. Looking good! Thanks for sharing the learning process on the engraving with us.
  6. You're getting all kinds of mileage out of those 20mm shell casings. They certainly bring a neat material and talking point into the knife. The leather decoration is great. I've never thought about going at it with a wood burning iron. I'm assuming the leather was completely dry when you did? In the pics it looks like it might still be damp, but I wouldn't think that would work out well.
  7. Should be a pretty easy "Drop in" replacement for an appropriate PID controller.
  8. My approach is similar. I get things set to where the spring is nearly flush in all 3 positions with a few thou (~0.1mm) extra to allow me to grind everything perfectly flush once the center pin hole is in position. Then I clamp the spring to one liner in position with the blade open. Next I pull the blade off, and measure from the belly edge of the liner to the spring so I can calculate what my new target for this dimension is once I put in the pre-load. Then I slide the tip of the spring towards the belly about 30 thou (~0.75mm) and reclamp it. Once I check that the dimension
  9. One of the tricks is getting the spring flush with the scales in all 3 positions. (Open,Closed, and Half-locked if you do that) I start by fitting the open position so that the others leave the spring a bit proud, and then file/grind away carefully on the tang to tweak the other positions.
  10. cut it up into elbow patches for all your tweed sport coats
  11. Nice. I've used my lathe for a lot of strange things, but never to power a transfer pump I'll have to remember that one...
  12. Hopefully I didn't steer you the wrong way on the temperature Gerhard. Here is a pic that shows one of my springs. You can see how much it is relieved (thinned down) in the area where it flexes. I can say with absolute certainty that if I try to close one without that relief, it will snap the spring. (Yes, I had to learn that lesson twice)
  13. I should look at my notes when I can get back to them to make sure, but I believe I have been tempering the 1075 springs at 550F. (Roughly 290C)
  14. The people around me know that I don't take myself very seriously, and that I'll do just about anything to make others smile. My organization shuts down for the year this afternoon, and I thought this might give our employees a chuckle. (My raging Yoda Christmas sweater and Santa hat today are also having that effect) I tend to unplug every year for a couple of weeks about this time. Before I go dark I wanted to wish a Merry Christmas to those of you who celebrate it, and wish warmth, happiness, and success in your endeavors to those of you who don't. See y'all in
  15. I tend to solder first then put the pins in at a much later point in the assembly process. Sometimes I'll use 316 stainless pins to keep the holes aligned while soldering because you can push them out easily afterwards. (Unless you really try to get the solder to stick to the stainless) Other times I'll solder on blocky bolster preforms, adn just drill through them and the tang as one piece. (This is inevitably the times when I find that the tang has hardened partially and I fight getting the holes through cleanly) Other times. I'll use hidden pins that don't come all the way t
  16. Yeah, it wouldn't work if I drew 3 circles and a straight line
  17. I don't think you will have any difficulties there! Your handles are always very striking. I can see the rune work you often have along the edge of the handle filled with gold on this one
  18. That is the same thermocouple I use in my forge. I don't have it connected to a PID controller, just a thermometer. I only use it when I am judging the temperature of the forge and/or the part for welding. They don't last forever, especially at welding temps. I only stick it in through the forge door when I want to know the temp so that it doesn't die prematurely. The polarity of the wires matters when you terminate the wires in the plug. If you don't get a reading at first, you may need to switch the connections. The thermocouple wire colors are standardized (most
  19. I haven't done the math recently, but if memory serves me right, 2 burners will be more than enough for that size cavity. I think you can save your 3rd one for for something else.
  20. Ahh, that is a cool idea. Now I don't feel silly at all
  21. Wow, nice piece. The gladius form has never really caught my attention until I saw your two posts. Something like this may need to go on my "To do" list.
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