timgunn1962

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About timgunn1962

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  1. Stuff happens. I think we all knew what you meant. Occasionally making a mistake is normal: it certainly doesn't mean you should stop thinking. I only pointed it out because it's the internet and someone encountering this thread at some point in the future might otherwise pursue a path of extreme frustration.
  2. If 1:12 is the "fast" limit, it seems like longer tapers would be "slower", so you'd be looking at 1:13 and onward.
  3. "Very close" is perhaps a tad optimistic. The gas flow at any given pressure varies with area, which varies as the square of the diameter (assuming the geometry of the hole entrance and exit remains the same). .0485"/.043" is 1.128 times the diameter, giving 1.272 times the area. On those numbers, the burner would run 27% richer than it would with the #57 drill. I actually get 3/64 = .046875 .046875/.043 = 1.09 times the diameter, 1.188 times the area and about 19% richer than the #57 drill.
  4. Reinventing the wheel springs to mind. That sounds a lot like an Amal injector, but without the facility to vary the mixture at will.
  5. The real answer is "whatever works best for you". There are waaay too many variables for a single answer to cover all the possible scenarios. Even the color of the DB will vary in different ways with different setups: some will tend to richen up more than others once the openings become restricted.
  6. Turning the pressure up often works.
  7. I can’t see the video. Not enough air is very similar to too much gas. Try .030” tips. And I’d get a couple of .024” tips in case you need to go leaner still.
  8. Can you fire it up in low light and see whether you have a significant amount of Dragons Breath? This will tell you whether you are running rich (fuel-rich: lots of DB) or lean (fuel-lean: little or no DB). There is a considerable amount of misinformation about burners. Many folk will tell you that you need high CFM from a forge burner because they have successfully used a burner that claims to have a capacity of 200 CFM (for example). Usually, the fans in question are rated for an open inlet and outlet and can only produce a small pressure rise when throttled. If the fan can flow 200 CFM with a fully-open 3" discharge and the discharge is reduced to 1", that's 1/3 of the diameter and 1/9 of the area. That 200 CFM fan is now closer to a 25 CFM "system". Using a vacuum cleaner, which is designed to produce a large pressure rise and to move air against the restriction imposed by the hose, you are likely to be getting a large proportion of the vacuum cleaners rated airflow to your burner. I am pretty certain this WILL be waaay too much air, but checking for DB in low-light is the best way to be sure. We usually want to run with a fuel-rich (reducing) forge atmosphere to minimize Oxidation of the workpiece. I calculated that each CFM of airflow will burn with 0.308lb/hr of Propane to produce a Stoichiometric forge atmosphere (Stoichiometric is a precise technical term which probably corresponds quite closely to "neutral" in smithing parlance). A rich mixture will require even more gas per CFM of air. Googling "shopvac specifications" gets a first hit for a spec that shows 5.1 cubic metres/minute, or 180 CFM, and 1525mm of water column, 60" WC. Peak rated power is 1400W. Even if you were only getting half of that shopvacs rated flow to your burner, you'd still need 0.308 lb/hr/CFM x 90 CFM = 27.72 lb/hr of Propane per hour. I've just used the first spec I found. Your vacuum may have a completely different spec, of course. In your position, I would fit a tee and two valves to the air line: one valve to throttle the air going to the burner and the other to regulate the amount of air being bled off from the tee. The air would come out of the vac into the tee unrestricted and both the exits from the tee would be restricted by the valves. To help understand what is going on, I would fit a U-tube manometer to the existing steel air pipe so that you can measure the pressure. Once you have things set up to your satisfaction, it is worth piping the bleed-off air to an air curtain in front of the forge to keep tongs/handles cool. It's worth keeping this in mind when you put things together.
  9. It would help to know what type of blower you have. If your blower cannot tolerate inlet throttling, there's a pretty good chance it will not tolerate discharge throttling either. If it can't take throttling and can't be speed-controlled, you might find you need a tee with one leg to the burner and the other bleeding off surplus air. If you do, then it is a really good idea to route the bleedoff to an air curtain in front of the forge, keeping your tongs/handles cool. Ball valves work and can be cheap, but have horribly non-linear characteristics and, with 90 degrees of travel, do not give fine control. Many use gate valves with some success. They are designed as shut-off valves, rather than control valves, but are reasonably good at controlling flow in this application, thanks to their fine-threaded adjustment: typically 10-20 turns from fully-open to fully-closed. Globe valves are normally the "correct" tool for the job, actually being designed to regulate flow and having similar fine-thread adjustment to the gate valves. That said, anything that works well enough to get the job done is good and the cheapest thing that gets it done well is optimum for most of us.
  10. From what I can find on t'internet, 14 nanometre seems to be about the optimum particle size for getting the concentration high. I don't know what that relates to in terms of specific area. The commercial rigidizer I've used in the past had a Specific Gravity of a little over 1.1. The best I managed to get with Cab-O-Sil M5 was about 1/7th of that concentration: an SG of around 1.015. This was multiple volumes of the Cab-O-Sil in a volume of water. It was the low achievable concentration that had me researching particle sizes and concentration online. Low concentration seems to be no real problem if you have time and good drying conditions: you just make multiple applications.
  11. That looks a lot like a Devil Forge burner in the photo. If it is one of theirs, they seem to be pretty well sorted, in my rather limited experience of them. You can make the flame hotter/ less-reducing by opening the choke and cooler/more-reducing by closing it. You can increase the amount of flame (heat input) by increasing the gas pressure and reduce the amount of flame (heat input) by reducing the gas pressure. The adjustments will be progressive, but not linear. Have a play with the adjustments in the dark and see what happens to the temperature and Dragons Breath. It shouldn't take long to get a feel for what does what.
  12. I'd roll a kaowool plug to put in the back as you suggest. That will reduce both the volume and the open area (no back port, though you can leave a gap in the middle of the plug if you need a pass-through), then I'd roll one or two layers of kaowool inside the front end to reduce the open area to little more than is needed for workpiece access. That will reduce the heat loss considerably and let you turn down the air and fuel. There will be a limit to what you can do before the mixture speed through the burner drops below the flame speed and you get the flame burning back into the burner tube, so watch for this. You also want the open area to be at least 5 times the burner area, preferably 7 times. If you just have a front opening and make it 2 1/2 times the burner ID, you'll have 6 1/4 times the area. I'd probably just use kaowool initially, use it outdoors and wear a mask, until I had some idea of whether it was giving the desired result. Then coat the kaowool and immobilize the fibres for longer-term use. I'd try very hard not to do anything irreversible unless/until it does everything it needs to do.
  13. I don’t know how easy it will be to get K26 IFBs in Belgium. The K26 seem to be made in the USA and the JM26 equivalents are made in Italy iirc. The specs don’t usually include anything on resistance to thermal cycling. I think it’s basically a case of forge builders in the USA having found that the K26 IFBs seem to hold up better than others that have been tried. I don’t know of a source of KastOLite30 in smaller-than-full-bag quantities in Europe. If you have to buy a full bag of 25kg, 55lb, I’d probably try casting a lining in the IFB Forge you already have first and keeping the rest for planB.
  14. Which gas jet are you using in the T-Rex? lots of folk seem to go for the biggest jet available, thinking more gas = hotter. It’s not quite that simple and in many cases a smaller jet will get hotter and use less gas. We tend to want to burn rich/reducing to reduce scaling in the forge, but going too rich reduces flame temperature. It might be worth investing in a set of mig tips in the next smaller sizes and giving them a try. It’s not guaranteed to improve matters, but it is cheap and the odds are pretty good: It’s certainly a lot cheaper in time and effort than building a ribbon burner and a couple of hours should tell you whether it improves things.
  15. With the caveat that I'm also not a caster, it looks to me like you want to flux liberally to prevent Oxidation and open up the choke fully. If it's a Devil Forge burner, mine seemed to be slightly rich of stoichiometric when fully open: it seemed like someone in Lithuania had put in the effort to do it right. Turn down the pressure because it'll get a lot hotter with the choke fully open. I'd try 5 PSI and adjust from there to suit your setup. If you go too low, you'll get the flame burning back up the burner tube once things warm up.