Gerhard Gerber Posted May 2 Author Share Posted May 2 Again, thank you @timgunn, you only lost me in places, several more readings might solve that Quote We therefore use a big thick lump of an insulating refractory material as the working face of the burner in order to dramatically reduce the heat flow to the plenum face. Gotcha, so if I get it horribly wrong there'll a boooom to let me know Turns out I couldn't find the rectangle tubing I'd mentioned, small end is narrower than my square tubing.....which will have to do. One good thing is I've figured out a great way to connect my plumbing to the steel body of the burner. I'll be coming in from the top, so I have to figure out how&where to put the baffles to spread the mix evenly over the burner. The trip to my friend with the working forge is seeming less likely, work and my puppies are getting in the way a bit. I've got a few days off due to public holidays, so I want to start fitting the inso wool to the forge and experiment with my refractory cement, get the right mix for the burner and the inside of the forge. I'll use a local machinist to get the mig nozzle in the mix. My one remaining concern is I'll have a longer and narrower burner than most I've seen, since I've solved connecting the plumbing to the burner I was wondering if I can't split the feed and come into the burner at two points? Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted May 27 Author Share Posted May 27 Progress..... 2 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted May 29 Author Share Posted May 29 My local advisor is of the opinion that the jet needs to extend past the T-junction, and I should only have a single layer of inso wool. My original plan was to have two layers, I'm glad I have enough for three layers because I think the interior would be too big with only two. I would appreciate some opinions on both. I plan on testing the burner before resorting to having it rebuilt, but to have less layers I would need to downsize the body of the forge. At this stage my plan is to weld on the one end plate, use cardboard construction the size of the interior of the forge and chuck in refractory cement around it, standing on the back end. Link to comment Share on other sites More sharing options...
Geoff Keyes Posted May 29 Share Posted May 29 If you have access to some sort of refractory, you could build an interior shell and put the wool inside that. Or a smaller shell, that works too. Could you section the a piece out of the shell and reduce it that way, or is a new shell simpler? A burner like that is good for about 300 cui (about 5 cubic liters). You will probably need an opening at both ends, venturi burners are fussy about back pressure. Just my .02 (USD)' g "The worst day smithing is better than the best day working for someone else." I said that. If a thing is worth doing, it is worth doing badly. - - -G. K. Chesterton So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy. Grant Sarver Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted May 30 Author Share Posted May 30 I can grind out strips on the top left and bottom right corners and try to weld it back together if necessary. I have a 25L drum of refractory cement ready and waiting. Link to comment Share on other sites More sharing options...
Jerrod Miller Posted May 30 Share Posted May 30 More layers of wool won't be a problem. Technically it will insulate even more, but past 2" you start to get diminishing returns. Just need to make sure your refractory is strong enough that all the give of 3 layers doesn't cause it to crack, but that is true with thinner layers, too. 1 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 10 Author Share Posted June 10 Elephant eating practice, one birdshit-weld at a time 1 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 17 Author Share Posted June 17 Only one crayon broke & floated, counting that as a win Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 17 Author Share Posted June 17 Burner test 1 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 19 Author Share Posted June 19 I resisted the urge to open the mold yesterday, but I'm not very hopeful considering how the leftover refractory dried, very crumbly..... Its a dark grey colour, most others I've seen looks loser to white. We'll see in a few day I guess..... Link to comment Share on other sites More sharing options...
timgunn Posted June 19 Share Posted June 19 I'm guessing it's hot and dry in Windhoek? Many/most castables are hydraulic setting and need to be kept moist for a good day or two, much the same as concrete. The leftover will almost certainly have dried out much too quickly (lots of exposed surface area) and may be completely unrepresentative of the block. 1 Link to comment Share on other sites More sharing options...
Dan Hertzson Posted June 19 Share Posted June 19 The color of your castable can certainly change after firing. In my experience castable with a larger proportion of alumina does tend to be whiter after firing than some others. If you have a heat treat oven, you may want to fire your castable slowly in there. Note to keep the door cracked open a little to let off all the initial moisture that gets burned off. If you have to recast, consider relieving some of those sharp edges in the steel portion of the burner that hold the castable in place. I've had experience with the castings cracking there over time. I would be more concerned about your welded nipple connection (Make very sure you bubble test it. That is a bad place to have an air/gas leak). Also your internal baffle appears to be more of a pressure plate inducing extra mixing (which won't hurt, but isn't the original design intent as far as I can tell), than a baffle plate used to spread the air/gas flow from the mixing chamber out to the furthest outlet ports. Will be interested in seeing how things work out. Can't view the video currently. Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 20 Author Share Posted June 20 22 hours ago, timgunn said: I'm guessing it's hot and dry in Windhoek? Many/most castables are hydraulic setting and need to be kept moist for a good day or two, much the same as concrete. The leftover will almost certainly have dried out much too quickly (lots of exposed surface area) and may be completely unrepresentative of the block. Supposed to be winter, but you wouldn't say that standing in the sun.......bone bone dry. It's still in the mold, would you suggest wetting it a bit? Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 20 Author Share Posted June 20 20 hours ago, Dan Hertzson said: The color of your castable can certainly change after firing. In my experience castable with a larger proportion of alumina does tend to be whiter after firing than some others. If you have a heat treat oven, you may want to fire your castable slowly in there. Note to keep the door cracked open a little to let off all the initial moisture that gets burned off. If you have to recast, consider relieving some of those sharp edges in the steel portion of the burner that hold the castable in place. I've had experience with the castings cracking there over time. I would be more concerned about your welded nipple connection (Make very sure you bubble test it. That is a bad place to have an air/gas leak). Also your internal baffle appears to be more of a pressure plate inducing extra mixing (which won't hurt, but isn't the original design intent as far as I can tell), than a baffle plate used to spread the air/gas flow from the mixing chamber out to the furthest outlet ports. Will be interested in seeing how things work out. Can't view the video currently. If I have to recast I hopefully have different refractory to try, some leftover from my neighbour.....if there's enough. I'm worried about my welding as well, best part of a day's welding and grinding to get it that far, and last weekend after relatively successfully welding on the ends I put a few more blobs of weld anywhere that remotely seemed to need it. I wanted to test but couldn't figure out a way to seal one of the openings. There are two outlets to the sides just below the baffle, I'm hoping........ I marked the video not suitable for children......maybe? 1 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 20 Author Share Posted June 20 Looks solid and busy baking it, crayons won't let go and I don't want to force it 1 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 20 Author Share Posted June 20 I made art, and maybe a ribbon burner 2 2 Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted June 26 Author Share Posted June 26 Didn't get much done this weekend for various reasons, constructed and welded on the collar where the burner goes in the forge. Last thing yesterday afternoon I couldn't resist another test burn. It was outside in the wind but there were flames at most of the holes, big yellow flames. Played with the gas feed a bit using the regulator, but the flame dies pretty quickly, didn't think of adjusting the air supply. I'm a bit worried about the height of the burner vs the thickness of the insulation, at this stage the burner would be pretty deep in there. Have to decide if I need to shrink the housing a bit. Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted July 6 Author Share Posted July 6 First chance to have a look on the forum this week Last Saturday I chopped two corners out of the body to get it smaller, wanted to remove 10cm but fortunately decided to start with 5cm, tack and fit the inso wool to check. Managed to get those little fibers all over my arms and gut, itchy rest of the day. Used a friend's MIG welder to get it back together. Had friends over who are busy with knife projects, being late in the day we decided it was time to play with the burner. I drilled out the holes again and surprisingly there's still a lot of crayon coming out. Decided to shorten the whole system so the fan is connected directly to the valve. Ran the burner for about 20 minutes till the gas ran out. Learned in the process it favours the one side, turning down the gas supply and when it was running out only one half of the burner has flame. Market this Saturday, hopefully the afternoon I can tack on the one end and start prepping for the cast weekend after that. Has to be done in July.... Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted July 27 Author Share Posted July 27 I hope to cast the refractory in the forge this Saturday, but I have a design decision I'm struggling with. One end of the forge is welded on, I need to make a hole in that end before casting that matches the cavity I'll end up with. I've made a cardboard & masking tape miracle around which the refractory will be cast, problem is the shape. Do I make it round, or rounded top and flat bottom? At this stage the mold is rounded top with flat bottom, but easily modified. I don't know, can't make my mind up Link to comment Share on other sites More sharing options...
Charles dP Posted July 30 Share Posted July 30 FWIW, mine has a flat floor. It might interfere with the swirl a bit but I think it heats more evenly where the whole blade contacts the lining (rather than just the edges). Of course this depends on the width of the blade and radius of the forge. "The way we win matters" (Ender Wiggins) Orson Scott Card Nos qui libertate donati nescimus quid constat Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted July 30 Author Share Posted July 30 I went for round mostly because I figured it would be easier to make & match openings on the sides. I was surprised that by 5pm everything was done and ready for casting. It was a bit miserable thanks to a late winter cold snap, but decided to get done with it. Everything was going great until the first scoop of refractory went in, neighbor Mike immediately instructed my friend, beginner bladesmith and faithful assistant, also a Gerhard, to come home with him to fetch his leftover refractory.....back problems. My 25L bucket of cement minus what went into the burner with Mike's about 10Kg didn't even get us halfway. I'm a bit gutted, hopefully there's some refractory available, but I know even if I get it done it is compromised and probably won't last long, expensive learning. If I can't get refractory I plan on building a new brick forge, I have some of the proper white fire bricks and a good venturi burner. Should be able to put that together in on Saturday, then I can start making knives before 2024 arrives Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted August 28 Author Share Posted August 28 On 2/1/2023 at 8:32 AM, Gerhard Gerber said: Got my fan from the UK, we had to pay import duties so it was quite a bit more than I planned. On second thought it was the same price as a jacuzzi pump several years ago, so not bad considering inflation. Please tell me it wil do the job? Got some advice from locals to take it really slowly to allow the refractory to cure completely. Painted stand with red oxide primer and the forge with high heat spray paint and assembled the lot. Seems I'm jinxed as far as building burners and forges are concerned. Lit the gas first, opened the tap for the air feed and just got bigger flames coming out the ends of the forge. At this stage my only theory is not enough air, or too slow, few times the wind blew into the forge exactly right the burner roared properly for a second. I have a pressure gauge on the regulator now, tried every possible combo of air & gas flow, no joy. My diagnosis is the fan is just not making it, burner worked perfectly outside the forge, seems there's too much back pressure with the burner in the forge, and the doors are not even fitted. My only idea at the moment is one size smaller pipe from the fan to the burner, if that doesn't work I guess I need a bigger fan. Fan was the big thing holding me back for years, no idea if I can find something else locally, but I'm pretty sure I won't be willing to pay the price, shop blower is the next option. Any thoughts or suggestions appreciated. Link to comment Share on other sites More sharing options...
Alan Longmire Posted August 28 Share Posted August 28 2 hours ago, Gerhard Gerber said: no idea if I can find something else locally You still have IT guy connections? Call a photocopy repair place and see if you can scrounge the fan off an older photocopier. Link to comment Share on other sites More sharing options...
Matt Walker Posted August 28 Share Posted August 28 Can you get your hands on a leaf blower. It'll probably be too much but some of the pressure could be vented for an air curtain. Fabricate a butterfly valve to control what goes into the forge. https://www.amazon.com/Sun-Joe-SBJ597E-All-Purpose-Electric/dp/B01M3UK0VY/ref=sr_1_4?crid=3O13Y85XBXHE4&keywords=leaf+blower&qid=1693230640&sprefix=leaf+blowe%2Caps%2C567&sr=8-4 1 Matt Walker https://www.youtube.com/@onedamascusmaker/videos Link to comment Share on other sites More sharing options...
Gerhard Gerber Posted August 28 Author Share Posted August 28 1 hour ago, Alan Longmire said: You still have IT guy connections? Call a photocopy repair place and see if you can scrounge the fan off an older photocopier. Yes I do, but honestly I've never seen anywhere near my current fan's size in a copier. My friend is willing to buy back the fan, it's ideal for coal forges, maybe just too "slow" for this application? Link to comment Share on other sites More sharing options...
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