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Dan Hertzson

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Everything posted by Dan Hertzson

  1. Very nice forging. I've not seen anyone forge in the harpoon as yet, so would love to learn those steps. What was the stock size you started with?
  2. Correct, long times at elevated temperatures will both result in grain growth (which can be reversed by proper heat treatment cycles) and decarborization (which is not reversible, but starts at the surface exposed to an oxidizing atmosphere and progresses inward with time). Actually I suppose that you can theoretically reverse decarborization by soaking the stock in a carbon rich atmosphere over a long time period at elevated temperatures, but I don't know of anyone who bothers with this.
  3. Third one works for me. Great lines. Did you forge it completely to this stage, or was there some profile grinding? In any event, that is some very clean forging.
  4. Fantastic tale and tribute. Well done. Sorry for your loss, I just had exactly the same thing happen with my father. At 90 years old and decent health, into the hospital for stomach distress, stage 4 pancreatic cancer diagnosis, gone in under 2 weeks. That was on Halloween. My father wasn't into the viking thing, but in his youth was an avid free flight model airplane competitor. Maybe I'll build one with an extra large tank and release it to fly away over the ocean.
  5. There are a couple of proprietary glass formulations that Corning is developing that are more thermally compatible with certain steels. I believe that Albert Paley has experimented with them. Still they are not anywhere near widely available, and you would have the problem of learning to manipulate molten glass (which has just as steep a learning curve as smithing) and the extremely rigorous temperature control needed to properly anneal it. Many common glasses are more compatible with copper, so if you switch to copper flowers it is more likely that you will be successful, but you would still have to learn a bunch of new skills. It is possible that using enameling techniques with glass frit would work, but I still doubt you would be able to hit the price point you appear to be going after, and I'm not sure it would be appreciably more durable than a good grade of epoxy.
  6. You do appear to need a better (more BTUH output) burner. Check out a MAP gas torch as a possible option, or if you are handy fab up a quick 1/2" Frosty TEE burner. I also recommend you use some of your previous failed experiments to make a proper insulated door and something else other than rolls of packing tape to support your forge.
  7. This is fantastic information. Please pin this topic!
  8. These all sound like exciting experiments, and I second (or third) the suggestion that billets instead of blades should be used for a middle school project. Unfortunately you will need some pretty high end test and fabrication equipment and/or safety equipment for some of the suggestions: Checking grain growth requires polishing, etching and high end microscopes, ideally with capability for photo microscopy (see Kevin Cashen: http://www.cashenblades.com/images/lab/lab.html) Etching using a variety of different acids requires a good selection of identical billet pieces to test as well as the dangerous acids in different concentrations. Ideally you should test these under a proper chemical fume hood, or at least in a room with extremely good ventilation. Please don't make the mistake I did when your age and trying to pickle a piece of jewelry I made... Maybe your science classroom has one? Also, how will you evaluate what is a "superior" etch? Will you be measuring the depth of relative etch between the steel types for each acid? What tool will you use for that (they certainly exist, but do you have access...)? Forge weld testing in the presence of more or less oxygen requires that you have the capability to reliably forge weld, a method to accurately determine the oxygen content of your forge at the point where the billet is being heated, a method to maintain the heat of the billet at a extremely stable level with forge atmospheres varying... I really like Alan's suggestion of using colored clay to mimic the results from cutting into a good pattern welded billet. You can get visually interesting results that are easy to show in a science fair using Fimo or Sculpy polymer clays, they directly mimic steel pattern welding, and can be baked in a toaster oven (for your report/presentation I suggest you pass on using the common "Damascus" tag for pattern welding. I'll leave that for an exercise for you to find out why...). However the problem is that the various outcomes are somewhat aesthetic, and may not be easily adapted to the scientific method. Perhaps you could do something on the order of "An investigation into how the number of different layers affect the pattern in Raindrop Damascus", or: "Use of 3 or more material types in Mosaic Damascus patterns", or: "Alternatives to the Ferry flip for displaying Mosaic patterns in pattern welded billets", or: " Use of Millefiori techniques to develop new Mosaic pattern welded surfaces". Of course the classic pattern welded blade science experiment would be to look into the whole etched "micro-serrations" issue and how it influences cutting capabilities verses an equivalent mono steel blade (i.e. 1084/15N20 tested against monosteel 1084). I think this has been done a number of times, but you could put your own spin on it. It does demand some fairly high precision grinding and polishing for equally sharpening multiple blades and repeatable heat treatment, not to mention a method of test cutting that follows some form of rigorous procedure, but that shouldn't be too hard to effect. Still, before I went down that rabbit hole I'd check what has already been done. Good luck. Also sorry for the long post (engineer, not scientist, as may be obvious from the post...).
  9. I've never needed a needle valve to regulate the flow in my builds. A good regulator can very precisely adjust the pressure within 1/2 psi. For a given fixed geometry gas train piping system the pressure of the gas at the source directly dictates the flowrate (unless some kind of compressor is added, reference the extended Bernoulli's equation). A good needle valve changes the piping system dynamics by adding a local restriction to the flow and allowing you to reduce the flowrate without adjusting the main system pressure at the regulator (if you initially set the regulator to run very rich at full air flowrate you can use the needle valve for more modulation, both up and down, but you need to plan that in advance). The same thing can be accomplished by adjusting the regulator, but you can also increase the flowrate using the regulator. It is my opinion that one point of control for the gas is better than two, but each to his own. A needle valve would certainly make it easier if your propane tank and regulator were located outside your shop. It will allow gas flow adjustment while viewing the results in the forge. I believe that the use of needle valves in DIY burners dates back to the time when folks on shoestring budgets did not wish to purchase quality propane regulators. Needle valves used to be cheaper and more common. The popular RISD glass furnace/ceramic kiln burners from the late 60's (I think) are a good example of this. The valves on torches are extremely useful because they are localized to where you are working, and the typical regulators are less precise. These days I use a commercial burner/mixer system for forced air/natural gas on my personal forge. It has a sophisticated zero pressure regulator which allows you to set the desired gas/air proportion (within a general range), then adjust the volume flowrate of the gas air mixture with a single control (similar to the upgraded shower controls where you set the temperature on one dial and the flowrate on another). It works very well, but I probably wouldn't use it if I hadn't gotten it for free while dumpster diving after a local university completely relocated their glass studio and threw away all the original piping. I would leave it at 1/4" and only change it if you have trouble with either mixing or controlling flowrate down to the minimum desired (watch out for preignition at low flow...)
  10. Depending on the length of tubing t may be worth upping the size of your propane supply to 1/4". You need to be prepared for friction loss at a certain point. It is kind of a mixed bag. On one side you have a restriction that could limit your overall propane (and thus heat) supply, on the other a smaller orifice at the mixing point will speed the entry of propane into the mixing tube, aiding in mixing. The compromise I've made in the past is to run a larger tube to the mixing chamber, then cap same inside the chamber with a drilled orifice. See this site for a typical example: https://www.joppaglass.com/burner/rt_alf.html . For a forge a multiport outlet isn't required (though they are nice, and a good choice for a long thin forge), and you can vary which arm of the TEE the air and gas enter on depending on your blower characteristics and fuel source pressure. I reiterate that I prefer variable pressure regulators over needle valves, but if you are set on the latter, be sure your's is rated for gas service.
  11. A recommendation for wrought iron axes: you might consider wrap and weld rather than punch and drift. That is the more common historical method of making these. Wrought has issues with splitting along the "grain" depending on how hot or careful you work, especially with the back of the eye close to the "edge" of the billet. You might want to forge weld a high carbon poll first before you try to make the split. If you do go wrap and weld, make sure you are careful with the tight bends at the back of the eye as well, very prone to cracking if you work the wrought the same as standard mild steel. Keep it very hot and it will behave nicely.
  12. I've run blown forges, glass furnaces and glory holes for many years. In all cases the blower was below the gas inlet and I've never had a problem in the blower either. The key, as others have stated is the sequence for lighting and turning off your forge. That being said there are a few other things I agree with: No small orifice is required for your burner construction. However I would substitute a proper propane regulator with gauge and a 1/4 turn gas rated ball valve for the proposed needle valve. In my experience needle valves are not reliable long term and it is nice to have a quick shut off in case of any issues (like power going off to your blower for whatever reason). That being said, a 1/8" -1/4" pipe connection to the burner mixer is a bit more common for propane. Your's looks like at least 3/8"? You need bubble tight joints on your fittings. This is easier to accomplish with the correct gas rated pipe thread compound. The allowable length of pipe between the blower and burner outlet is more a function of the blower capacity than any worries about burn-back. The only times I've seen people having trouble with preignition is when they let the mixer assembly get too hot. This is more often a problem when you are trying to run your forge at a lower temperature after it has been very hot, or light it when a chimney effect has come into play. In my experience this is less of a problem with multi-outlet burners (like your ribbon burner) That looks like a rather large forge for a first forge. What is your planned interior volume? Beware of gas hogs and try to plan for doors early...
  13. Really like this one. Were you looking at any source images when you came up with the design? Feels very authentic. Is it a "thru tang" with a rivet button? How did you achieve the patina on the blade?
  14. Those are very nice Gerhard. Starting to make me worry that my skills are not adequate for KITH submission. Did you rivet, like Lin, or forge/arc weld the loop closed?
  15. In a forced air forge you can avoid this problem by running your air source for a few minutes after you shut off the gas.
  16. No riveting on scales, right? Would a Lin Rhea style X-Rhea be acceptable? I was thinking about trying a version of one of the simpler ones...
  17. The best option for quieting down a gas forge is to use a multi-port burner outlet (popularly called a ribbon burner). While these are easier to design for forced air/gas forges they certainly can be used with naturally aspirated burners as well. Careful consideration to matching forge volume and configuration, burner size and multiport outlet are required. I believe that Dudley Giberson at Joppa Glassworks has a packaged design that is worth looking at. Note that they are still not quiet, but certainly quieter than a typical burner flare (or even worse a post mix burner system like the old Eclipse burners).
  18. Note: Cross posted with Doug. I agree completely with his comments. The other issue with the length of your forge is that, particularly as a beginner to forging, you will be heating far more of your stock than you can effectively hammer in one heating session. A long forge like that one is really only useful if you have a power hammer or press and are working architectural scale (or are using it for relatively low temperatures for heat treatment of swords (though I think a vertical heat treatment tank, ala Don Fogg, is a better choice there). The issue with heat treating too much steel for bladesmithing is more chance of decarb as well as wasted propane (not to mention a more complicated burner setup). I visited Albert Paley's studio recently, and his gas forge is no larger than the one you plan on building. IMHO an 8" forge length is pretty optimal for most bladesmithing (particularly if you have a dedicated heat treatment chamber). The real problem with gas forges is that no one design works for all smithing operations. That is where solid fuel forges shine. If you keep the current configuration I would recommend the following (all my opinion, so take or leave as you will): Replace the vinyl propane hose with hard piped copper with flare fittings or at least propane rated hose. Bubble test any joints up to the mixing tube. To run (3) 3/4" forced air/propane burners you will need a large propane source. A standard 20 gal barbeque tank will slurry up with that much draw. You will also need an adjustable propane regulator (0-30 psi minimum). Tank should be kept outside your building, if possible, with 1/4 turn shutoff valve at building entry. I recommend using a minimum 2" pipe size from the blower right up to the main mixer tube header (you can pipe your 3/4" individual burners for t-fittings off that header). This will allow you to use a blower with a reasonable airflow to static pressure ratio. Blowers of this type will be quieter and more efficient. I'm not going to do the calculations, but I expect that a blower that supplies around 160 CFM at 0.5" WG will be adequate. You will want some method of modulating the airflow from your blower. If you are scrounging, the new high efficiency furnaces often have combustion inducers with ECM motors that can be controlled with a 0-10 VDC signal. For a conventional blowers you will need a manual damper at the outlet or waste gate, to allow control of the airflow. Note that dimmer switches will not work well for the typical cheap squirrel cage blower motors and likely not on your leaf blower either for extended use. Make sure your pipe reducer/burner flares are well covered by the inner insulation layer/refractory. Otherwise they will burn up in use. It is extremely costly and difficult to coat the ceramic wool directly with ITC. At bare minimum you need to seal the surface first with a solution of fumed or colloidal silica and water. This will harden the refractory blanket and seal it. Otherwise the fibers become friable after heating and will get into the shop and eventually your lungs. Don't make my mistake and damage your lungs! Personally I like to have an inner coating of at least 1/2" thickness of castable refractory (Kastolite 30, or similar). If you ever plan on forge welding with flux, you need to think again about the floor of your forge. Hot flux will eat the blanket like water on cotton candy.
  19. The aesthetics and finish of your hammer are quite lovely. A couple of points from my experience forging and using this type of hammer: Often the hammer head, or the punched hole, are offset to keep the face at less than a true right angle to the main axis of the handle. The theory is that this helps with the primary task that this hammer type is optimized for: setting bevels. I see that you deliberately chose to go 90 degrees. What was your logic for that? The first dog's head hammer I made had a face just as flat as yours. It is now relegated to final planishing work as the flat face didn't move metal in any significant way without leaving edge divots. After you use yours some you may consider regrinding the face, if you have a similar problem. The better ones I've used have more of a dished face.
  20. IF you are making your own micarta you could use a fabric with a cross pattern already woven into it...
  21. This may be helpful for you to better understand file terminology: http://www.crescenttool.com/MagentoShare/media/documents/nicholson-guide-to-filing-2014.pdf
  22. Or just forge weld a collar around it if you are going traditional
  23. Looking great, as usual. Any trouble getting through the hardened tang to drill the pin holes and bolster holes?
  24. Did you use very high concentration of instant coffee? Clean your surfaces with a solvent (acetone or the like) before etching? Are the edge and spine corners significantly more polished than the other surfaces being etched? For what it is worth, I don't like to etch after final sharpening as I believe that if the etch is effective it must also remove something from the blade edge as well, potentially blunting it a little. I like the contrast of the polished edge with the etched surface I get from doing my final sharpening after etching, but understand that it might not be to everyone's taste.
  25. SSR are nice, I used mercury contactors for mine as I built it before SSR became more popular and cheap (and I had the contactors and PID controllers very cheap from a local liquidator). I also have gotten coils from a variety of sources: Dudley Giberson used to sell custom wound coils. (https://www.joppaglass.com/). His book is also quite good for design info. Old electric duct heaters that were removed as part of a demo operation I was involved with (nice heavy weight open coils with ceramic wiring standoffs. An old electric ceramic kiln that was being thrown out (should also have saved the bricks...)
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