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timgunn

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timgunn last won the day on August 29 2020

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About timgunn

  • Birthday 03/15/1962

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    Lancashire, UK
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    Tools, science, food, wine. Making things that "just work".

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  1. A heat-treat kiln will usually do a better job of firing ceramics than a pottery kiln will do of Heat-Treating blades. The size thing is fairly obvious, but there are fairly fundamental differences between the tasks. For ceramics, the aim is to do heat-work: there is quite a large permissible band around the nominal temperature over which the temperature can fluctuate and, as long as the average temperature is held for the correct time, everything is fine. For Heat-Treating blades, we are much more concerned with precise temperatures and our acceptable band is much narrower. Typicall
  2. Not wishing to be that guy, but... Are you likely to be able to get a straight, burr-free cut with whatever you can put together? I'd hate to see anyone spend the time and effort of making a guillotine, only to find that it takes as long with the grinder to deburr as it does to cut the pieces with a slitting disk in the first place, and you then have to stack twisted pieces instead of flat ones. A 14" Carbide-toothed chop-saw would be my choice, but I am somewhat biased because I already have one. It's noisy, throws nasty sharp chips and is nobody's idea of a fun way t
  3. I use the Amal injectors. There is nothing better that I've found, and I've been looking pretty hard for many years. Availability has been rather intermittent for a while now. When available, shipping to the US should be no problem, since Burlen, who took over the Amal IP, primarily supply carburettors and parts for old British cars and ship all over the world. It is worth noting that the Amal injectors use 55-degree BSP threads based on the Whitworth threadform, rather than the 60-degree NP threads used in North America: not a big problem, but something to be aware of.
  4. I think I'd file down the key to fit the slot depth, rather than file down the slot to fit the key depth. The key will come out and allow you to do the filing in a vice (vise) where it's easy. I've done enough filing to know I'm not good at it. Using a safe-edged file to increase the slot width should keep you from chewing up the bottom of the slot by running the safe-edge on it. If you need to deepen the slot, the safe-edge moves out of the equation and your opportunities for lousing things up increase considerably because you are working in 3 dimensions instead of 2: think flying
  5. A file will do it. As said, you will want a hand file (less than about 4mm thick) with a safe edge and you'll need to work on both sides evenly to keep things aligned. Are there any grub screws in the pulley? If so, they'll make things a bit less critical in terms of slot accuracy. The bore provides the 90-degree alignment to the shaft, the key/keyway provides the driving force and the grub screw(s) prevent axial movement. In essence, the likelihood is that you'll end up with a slot with convex sides (unless you are good enough with a file that you'd have just done it a
  6. I promise that it's a single piece ball valve, aka one-piece ball valve. I have no idea whether the ones in the video are any good, but the video seems to show the difference between the different numbers of pieces. I think a 1000 PSI rating is pretty standard in stainless and the bodies usually seem to be cast. In Carbon steel, they are usually machined from Hex bar stock IME and may have higher pressure ratings. They are almost never automated and any slop is usually between the handle and the spindle, though I only have experience of manual valves t
  7. The industrial controllers generally allow the operator to adjust the setpoint in "vanilla" PID control (no ramp/soak), but anything beyond that often requires a God-level passcode that allows access to absolutely everything. I have had a knifemaker, with an oven I'd built, call me because he'd hit a wrong button whilst working through a menu and changed the thermocouple type from N to R or S. He was smart enough to recognize that he was getting temperatures in the tempering range when set for the Austenitizing range and called me. I'd made a similar mistake in the past, so quickl
  8. I don't know how familiar you are with PID temperature control generally. I set up PID controllers in my day job: I'm certainly no expert, but I'm not completely clueless. There were a couple of things I didn't fully understand about the process when I built my first HT oven. With the benefit of hindsight, I would have appreciated being told. Pottery kilns tend to provide "Heat-Work" and the important parameter is the average temperature maintained over several hours. The workpieces usually have considerable thermal mass which helps damp out temperature fluctuations.
  9. Hate to be that pedant, but it makes a difference when searching for info on something you are not already familiar with. It's "Curie point."
  10. Just a thought: what shape were the links? Some WI chain has an oval link in WI, with a crossbar bit in the middle that makes the oval into a pair of back-to-back "D"s. The crossbar is intended to take a compressive load and stop the link stretching to a longer oval under tension. The crossbar can be a completely different material because it only needs to resist compressive loading and sees no tension. I think the crossbars were probably Cast Iron in many cases. I know it's pretty unlikely, but if you've got a links like that and are trying to treat both materials the
  11. I'd strongly suggest reading John Nicholson's thread on the jizzer in the stickys. It's simple and it works. I have built a few forges, including some intended specifically for HT, mainly because actually making knives seems like bloody hard work and forges for other folk to use are well within my comfort zone. It does mean that I probably spend more time on the forge than a typical smith would Bottom entry works very well full-size (55-gallon drum), but I found that top-entry, bottom exhaust worked best for me, with a chamber about 8" diameter and 18" long. To be hones
  12. I think it's (probably) a one-piece ball valve and I'm guessing at 1" for the 1/2" bore. These are always reduced-bore valves (AFAIK). It's worth doing a quick web search for the differences between 1,2 &3-piece valves so you've got an idea of what you are looking at. One-piece are pretty similar to 2-piece except that the bit that screws in and holds the seat in, has the same (parallel) pipe thread as the nominal size of the valve. I'd probably have a look for another one-piece that looks similar enough that you can pilfer the moving parts and transfer them into the body you
  13. Sorry: fat-fingered. Please let us know what controller you use and how well it works for you? I for one would appreciate some insight into the alternatives to a VFD-and3-phase-motor approach.
  14. I'm not sure what the speed:torque characteristic curve of a shaded-pole motor looks like. I have only ever encountered shaded-pole motors in fixed-speed or variable-speed-fan applications and assumed they had a variable-torque characteristic that made them suitable for use with variable-speed fans, but probably not with constant-torque applications. I could, of course, be completely wrong. If yours does have a variable-torque characteristic, it is unlikely to work well at reduced speed on a grinder.
  15. I know it's probably not necessary, but I'll say it anyway: dry it out properly before you fire it up. Depending on the "refractory paste" you have used, this can take from "a bit longer than you'd expect" to near-geological time. The worst stuff I used was a readily-available "refractory cement", which I assume was actually clay-based. After a couple of days I thought it was dry enough, but it wasn't. On first firing, the surface dried out pretty much instantly, the moisture behind it flashed to steam and lifted the surface as bubbles. These broke and flakes fell off, then the pro
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