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Dan Hertzson

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  1. I'm definitely in for a hatchet/hand axe, though not a great fan of integrals. I've never done a double bit one. Might try a small Nessimuk.
  2. Also note that in the sushi knife class I took the instructor "precurved" the concave side of the blade mechanically before grinding. In that case we were using single side laminated steel (HC on the concave cutting side and mild on the beveled side). He did the curving cold, after forging and annealing, using large radius clapper dies and a big, slow power hammer. When I tried to emulate this at home I used a swage block and large radius top fuller to achieve a similar effect. Not sure if this is a good idea for non-laminated steel, and the blanks are certainly prone to warping in final heat treat (and expected to do same apparently - I think Murray Carter discusses addressing this in his book). I think you can make a simple one yourself, that isn't water cooled. I suspect that a mister system would work to keep the belt cool enough, or possibly in combination with a graphite pad behind the belt as well to reduce friction.
  3. I used a 12" wheel, but my blade wasn't nearly that wide. You might want to look at water cooled large radius plattens.
  4. You still planning on casting stainless steel, but want to do it on a budget? I strongly recommend that you get some direct, in person, training with someone who casts steel or cast iron on a regular basis. Barring that I would recommend you start with a much lower temperature casting material like pewter or aluminum before you attempt any steel or bronze. What exactly is it you want to make out of stainless steel? Perhaps there is an easier, or at least safer, method to achieve your goal.
  5. Well you can buy a manual reset valve configured to be initially manually opened then default to the closed position on loss of power. This may be an expensive option. Or you can go old school and wire it up with a relay and pushbutton switch. Been a while since I did one of those, so I'd have to recreate my wiring diagram, but it is pretty straightforward logic if I recall correctly. You use a NC valve that when energized opens. Then in addition to the on/off control system switch and fuse (you are going to include those right?), you include a momentary push-button switch that energizes both the relay and and a holding contact. The NC valve is also powered through one of the relay's NO contacts so that when the power is on it both holds the relay closed and the valve open, but when the power fails, or at startup, you need to manually push the button. See the attached image for details (sorry for the image size, new computer at work and don't have image processing software).
  6. Typically the green NC solenoid valve is wired to require a manual reset.
  7. Some stainless steels are not particularly magnetic. I don't know about Nitro-V. However if you have too much retained austenite you may not have achieved the hardness you want from the steel. Have you seen this procedure for heat treatment: https://knifesteelnerds.com/2019/09/23/nitro-v-its-properties-and-how-to-heat-treat-it/? Do you know if David did any freezing or cryo after the quench? As far as holding the blade for grinding, there are certainly several techniques to hold a blade without use of a magnet. You can free-hand hold the blade and just grind on your platten, use a tool rest and grind either by hand or with a jig, use a push stick with and of the options (except the jig)...
  8. Yes it certainly does matter. If both devices are line voltage, 120 V, they need to be in parallel. Also the following : a diverting solenoid valve rated for propane may be expensive and hard to source. Just use another NC 2 way control valve on the high fire side of your gas train. make sure the quick connect is rated for gas service as well. Standard air quick connects won't work. not sure why you need 2 thermocouples. In any event use the thickest ones you can get and protect with wells so can be replaced as they break down. Type K are unreliable at over 2100 Deg F and type R or S are expensive. Use proper thermocouple wire.
  9. Not sure how to address this with a sideblast forge. In a typical bottom fired forge, the trick I learned is when in "idle" mode with the blower off (banked forge) to keep the ash dump open to induce a flow of air through the grating and bypass the blower. It doesn't hurt to poke a venting hole in the top of your green coal mound either. I would also make an effort to avoid banking your green coal with damp coal, or wetting it down after making a mound. I'm sure someone with more experience with side fired coal forges can be of more help. Till then I'd be careful, you can get a pretty good "pop" from a coal gas explosion and folks have lost shops for less.
  10. Hard firebrick doesn't insulate well at all, making it a challenge to get up to working temperatures and inefficient. Just because they are easily available doesn't mean it is a good choice. You should have learned that from your plaster/sand refractory adventure. The configuration of your forge should also match your burner outlet to get a good spread of heat. I recommend more research.
  11. Kind of reminds me of the old Square Wheel belt guard assembly, though that is in metal. Hot sparks will fly off your belts as you grind knives, and not all will make it to the metal capture tray below. With interior corners to collect dust and the like you may have a problem with fire from the hot sparks, so keep an eye open in use. I'm sure it is not a critical issue, just one to keep an eye on during and after you finish grinding each session. Not a dust issue as much as an overheating issue. Even TEFC motors need to be cooled and have sufficient air circulation for same. The box idea is interesting from a dust capture standpoint, but if I were building something I'd look into the new type of downblast table capture system that NESB is putting in their new shop. Personally I would only use the hose and vacuum system when using the grinder for wood or other non-metal handles. Make sure the right hand side access panel of the box is very easily removable. You will be changing belts often.
  12. If you are referring to a mild steel pipe reducer, not some esoteric foundry only piece of equipment, they are certainly not required for burner operation serving chambers like forges, foundries, glass furnaces... However, I believe that the rapid change in diameter makes a distinct transition point between the fuel air velocity in the mixing tube and the burner outlet. This makes it easier to tune the burner to operate with the flame front in the right location, particularly outside a chamber in free air. High temperature castable burner outlets have been around for a long time as well. I used them on glass furnaces back in the 80s, and I'm sure they predate that. If you really want to blow your mind look into multi outlet burners... Note, some burners require secondary air induction for proper operation as well. That gaping hole you mentioned. Might be best to get a little experience designing, building and operating burners before you try design changes. I'm all for experimentation, but it helps to start from a proven design so you know what is an improvement and what is not.
  13. Jerrod, You are the expert and I agree with everything you are saying. If you look back over Alex's posts the only info on the configuration of the items he wants to cast appears to be 1" or 2" cylinders, of an unspecified length, made with steel of different densities. I'm not sure if he realizes the relatively limited difference in densities for different common steels and he doesn't appear to have any experience casting at all. I'm not sure whether this is a real project or a hypothetical (though he does indicate a bunch of urgency to get it accomplished). I don't know if this is a high school science fair project or something for the JPL using high tech proprietary metals . I do have some serious reservations about a beginner making their first casts with molten metal over 3,000 deg. F. Without any additional information I simply don't see why he doesn't just have his cylinders machined.
  14. If it hasn't cracked or broken yet it isn't too late. As far as I know, for most steels, it is usually best to temper your blades as soon at they reach room temperature after the quench process to avoid potential cracking from the stress induced during hardening. Some folks temper in toaster ovens, though they aren't as consistent heaters as larger kitchen ovens. Still you can often get them cheap, and I've found that if you bury your blade in a tray of sand for additional thermal mass, and calibrate the oven to be sure it is working as expected, they are adequate for a snap temper at least. The controls on the newer electronic toaster ovens seem to be even better than the older dial units, but YMMV. Why not pick one up for your shop?
  15. Still very confused about your insistence on casting the steel or stainless steel for your weight project. I thought you got pretty clear direction regarding safety considerations as well as the need to post-process the steel cylinders by machining if you make these by casting. Why not just purchase the steel bar stock and machine it to size, since you will have to machine anyway to get the tolerances required? The energy costs for casting and the virtually unavoidable initial failures due to inexperience will most likely offset any savings you anticipate from using scrap material. I think you got some good advice on your other posts regarding working with an experienced caster if you won't deviate from your plan. I'm sure they can answer your questions regarding casting molds, dealing with inclusions and slag, sprue and vent design, material property changes due to melting your stock, annealing requirements ... Here is an example of what is available from only one online supplier: http://www.speedymetals.com/c-8266-category.aspx As you can see they have a number of different alloys in the rod sizes you are looking for. If I was in a rush to complete a set of weights for a project, that is the direction I would go.
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