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About D.Rotblatt

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  1. Looking great! Good to see another burner with small holes and get some more data about them! If I read this right, it looks like you have 6 rows of ~22 nozzles each (about 66 holes), at about .11" each. At pressures over 10lbs it appears to be blowing off the block. For reference, I have 124 holes at 1/8", much closer together. I started with less holes, then worked up. It holds onto the block outside the forge and runs from 0 to 20+ inside with a stable flame. You may be able to double the number of holes you have. Possibly more actually as I haven't tried that, I just don't have room on mine for more holes (2.5 x 8" plenum). Also, blackburn doesn't happen at low pressures on regular burners until they heat up - after about an hour of forging, so you will have to try a long run to see how it works at low pressures (though those size holes may be too small for blowback). I've got to try that PLA burnout technique. Might be easier then lots of wax sprue in a wood block. Dan R
  2. At this point I just have to see if it is as efficient as a single burner with normal nozzle. It seems to take a bit more gas (using the same burner I used to use as an ejector) as a single nozzle burner, but it is heating up a 6-7" long area rather then a 3" spot. I'll get to it in time...doing major construction on my house right now, so I'm playing with feather Damascus right now when I have the time. Oh, and I measured the inside of the forge and it's around 190 cu inches. Still a bit of a guesstamit as the shape is somewhat irregular.
  3. As it turns out, my small 1/8" hole NA ribbon burner is now running in a forge about 4.5w x 6tall x 9" long. It's an odd shape, cross-section was a 3/5 circle with flat bottom, but I decided to shrink it to get more efficient heating from the ribbon burner and added another 1" of ceramic fiber to the sides...it's a kind of a triangular shape now with a truncated flat top where the ribbon burner is (pointing straight down). I'd guesstimate the interior at about 200 sq inches or so (I'd have to go down to the studio to measure it to be sure). I don't think I'd go smaller, but the burner is working fine, no back-burn issues and plenty of heat! Tiny flame cones, less then 3/8" long so combustion is quick. Can run the pressure down to where it doesn't pull any air, just a propane flame. Low temps are in the 1450 range. High is welding - 2300 or so, and I have welded in it. The ribbon burner on the above forge is attached by 3 bolts sticking up into 3 flanges on the plenum. I wanted a modular design too, so I did it this way so I could change the whole assembly out for a NA single or double burner or anything else (since it was an experiment, I wanted to be able do convert it back). Basically I just need to make any assembly that will fit the hole the plenum requires (2.5" x 8"). If I basically took a plenum piece, I could run a single burner into a hole on it and stuff it with ceramic fiber and swap it out for the ribbon burner. Does that make sense? may need to some pics if it doesn't. Let me know. Dan R
  4. I'll be interested to see. My comments are a hypothesis at this point, the one data point I have is that I tried to flare the nozzles a bit on a ribbon burner to get it to burn better out of the forge, and it did, but seemed to have poorer characteristics at low pressures in the forge (easier backfire)...but I didn't take down notes or anything, just casual observation. Dan R
  5. A flared nozzle slows the speed of the gas so the flame stays on or in the end of the nozzle rather then blowing off, but also this makes the flame closer to, if not inside the end of the nozzle. My thinking is that this is the opposite of what we want in a ribbon burner. The main issue in the ribbon burner is the face gets too hot and the flame can then backburn at low pressures into the plenum. We want the burner block to be cooled by the gasses flowing through the block, not heated by having a flame burn inside the block. If one was to try to experiment with a change in the nozzle shapes, I think trying the opposite of a flare, a constriction at the end of the nozzle to speed up the gas and push the flame a little away from the block. Bottom line, what is good for a single burner in open air, may not be good a ribbon burner in a forge. Dan R
  6. It's a 25 year old Reil burner with a #60 drill hole in the side of a 1/4" pipe...standard old construction. I think at lower pressures it runs ok, but now I will need to check the most efficient damper placements at different temperatures. Then I'll have to see how that relates when the same burner has a regular nozzle rather then the ribbon burner.... looking truly excellent! Glad the hot facing is working well. I'll be interested to see what the glass bubbles do. Nice idea using the bucket! Dan R
  7. The flame may be leaning down as I turn up the pressure, thus I am actually getting a more neutral flame at ~70% closed. That would make sense. With the damper closed down I'm getting 6-8" of yellowish dragons breath at 15 lbs. I seem to recall reading that the flame mixture in a RA burner changes a bit at different pressures, and the ribbon burner end may cause it to lean up more then normal. Got it. That makes sense. So in essence, the end of the burner is like the nozzle in a NA burner, pulling air in around it. Easy with a single burner, hard with any type of ribbon - slower flame, much larger hole. Especially two ribbon burners. Once more, ingenious idea (or application). I've got the idea now, I like it! Will you be using ceramic fiber inside it, or just a cast wall? I'm with your there! I remember taking an education class around '94 and learning how to research the web. All sorts of cool stuff, mostly from universities. No ads, only a few commercial sites. Then again, around that time I used to love spending the weekend at the UCLA research library tracking down primary sources for medieval metal technology in those square things some people may remember as being called "books". That'll be a lost art! Dan R
  8. In line with my earlier thought, I added an inch of ceramic fiber to my forge reducing the interior to about 4.5" wide and high. The burner is actually about an inch higher since the brackets didn't allow it to be lowered too much. Since the forge is 8" long, that gives it an internal size of around 180 square inches. Maybe smaller since the top is rounded (kind of...it's an odd shape now). Runs fine with the NA 1/8" ribbon burner, no problem with back pressure. Definitely getting hotter easier and quicker. Choke wide open. 5lbs = 1950, 10lbs = 2150, 15lbs = 2250, but didn't go up much at 20 lbs. So I closed off the top 1" of the door with some ceramic fiber and the temp jumped up to 2300. Then I played with he choke on the burner (it's a standard Reil burner going into the plenum), and closed it down about 60-70% and the temp went up to 2370. Two lessons learned: 1) a lot of heat leaves out of the top of a high door, 2) a reducing flame seems to be hotter in this forge or with this ribbon burner. Dan R
  9. Took me a few reads to get my mind around that... Lets see if i have it right. The forge looks something like that Parthenon - a 4.5" vertical cylinder, 10" ID, with a domed top. Two ribbon burners in the top with angled outlets to swirl the flame and focused on the center. Curved walls that can move/rotate under circumference of the dome. Baffles that can also move/rotate to change the size of the openings. Not a knifemakers forge, but a blacksmiths/iron artists forge. I like the concept. I've heard of forges with a wide flat top and bottom but no walls, burner in the middle to allow for heating of wide items. By containing the sides like you do, and using ribbon burners you should get really good heat. Thought: If I'm thinking of this right, why not make the walls fixed with large openings (and your moveable baffle doors) and have the the top able to rotate 90 degrees? An external metal ring around the top and above the walls would allow this and would allow you to change the orientation of the ribbon burners. That way you won't have to deal with moving walls and baffles, which, I agree, is mind boggling to figure out. And then there is the whole recuperative liner part...I'd need a diagram or pic to see what you are talking about that. Sounds interesting, does get the gears turning! Dan
  10. I'm going from stable 1450F to welding heats (Ive done a couple of welded billets 3x1.25x2" no flux), so it is very versatile with no backfiring. I don't know if it's more efficient then a regular burner, I seem to be running it at higher pressures for welding. I think because the heat is distributed over 6" rather then a 3" center, but for regular forging I keep it at the same 5-7 lbs. Like all ribbon burners, it's disadvantage is it's advantage. The heat is distributed very evenly in the forge. Sometimes I like a hot spot to work with, so a single NA burner provides that. One thing I'm thinking, is that I don't need as large an internal forge diameter with this burner (this forge is made from the smaller helium tank and has 1" of ceramic wool and IFB on bottom). The flames cones are only about 3/4" long. There seems to be no back pressure problem. I could run another 1/2-1" of ceramic fiber around the inside and I think it would make it more efficient. I make knives and swords, so don't need a wide forge generally. I think the burner, which is coming in from the top, could be moved down closer to the bottom as well. Actually, a square design might work well for this burner. Do tell! What are you thinking of (if it's not a classified secret)? Dan R
  11. Go for it! Would love to hear how your version works! Of course, you could do both....
  12. Didn’t sieve it, just a recommendation now. Vibrated the same, even though it had started to set up. Didn’t get bubbles, so it still worked. So far only made the one with small holes. But I will try to seive it on my next (I have another really old bag of mizzou). Planning to redo my forced air burner block with 1/8” holes...i think I can fit 250 holes on a 8x2” plenum in a 12” long x 6” diameter forge. Dan
  13. I had trouble getting the refractory between the rods due to the large grit in it. I used mizzou. Had to push little bits between the rods with a thin knife blade. PLA is brittle, so be careful. You may want to try to sift the dry refractory through a screen to remove larger particles. Vibrating didn’t work for me..,the grit was too big/space between rods too small and by the time I got enough refractory between the rods it was starting to set up. It was worth it though, my burner is great! I don’t think you want the rods to flair for a ribbon burner. I was thinking of doing the opposite to push the flame away from the block and keep it cooler, but it doesn’t ever backburn, so not necessary. Great use of 3D printing! Dan R
  14. I'm sure you've built it by now, but for others and future reference I have used the coating on 2300 ceramic blanket in a furnace. It does hold up pretty well, did many pours out of that furnace and I think it still has the same lining after years of use. Still, this is less use then a forge, as a melt takes under an hour, so 50-60 pours is only that many hours. Never-the-less, in a furnace the flame is pointed directly on the wall of the blanket and it works fine. Every few years I would add another coat or two of the zircon shell coating. Only takes 30 minutes or so, and then just fire it up. Heals the cracks from tong abuse. Dan R