tardster Posted January 3, 2019 Share Posted January 3, 2019 After 3 hours of searching the forums both through google and in IFI itself I still haven't found an answer to my question so I must ask unfortunately so here goes. When installing my burner into the forge how far should it go? Should it stick all the way through the kaowool and if so how far past the kaowool should it stick or sould it be partially through the kaowool like 1.5" of the 2" ? I watched one of those alec steele videos last night where he was building a forge. While building it he only went through the roof material (which was some sort of a brick material) about 3/4's of the way through it. I don't think that would work out to well with the kaowool material but I figured I'd ask just to make sure and finally should I use a little bit of the kaowool to close up the area around between the burner and its holder? Thanks in advance Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted January 3, 2019 Share Posted January 3, 2019 It's sometimes hard to find exactly what you're after. This particular factoid has been repeated many times, but that doesn't mean it's easy to access. Anyway, you want the end of the burner tube just inside the outer shell of the forge. If we assume 2 inches of fiber blanket and about a half inch castable refractory that would mean the end of the burner would be set back from the forge chamber by roughly 2 inches. Anything that is in the forge chamber will get very hot. Thin steel that is very hot will deteriorate rather quickly. It's best to coat the fiber blanket with something to seal in the fibers too. This could be castable refractory or something like a Plistex or Matrikote coating. Depending on your burner and forge you may or may not benefit from some amount of secondary air being pulled in around the burner tube. That's something you'll have to determine when you get the burner installed in the forge and running. Regardless, you do not want unsealed ceramic fiber blanket that is exposed to forging temperatures or that can be sucked into the forge during operation, so the burner port into the forge should also have the blanket sealed off. Quote Link to comment Share on other sites More sharing options...
tardster Posted January 3, 2019 Author Share Posted January 3, 2019 Thank you buzzkill. I put the kaowool in there (its 2" thick) and cut it out to fit most of the tip and lit up the forge just to see if everything was ok, plus I'm excited lol. As you said some of my tip does stick out past the kaowool and it got red hot so now I have to make sure to get all of the tip inside the kaowool and the castable once I finish it all up. My burner has 1 of those adjustable tips so my plan is to leave it where its at and make sure nothing sticks out. I let everything cool off and took a couple pics and noticed that after I shut it down the burner tube was pretty warm to the touch but while I had it going it was cold. I don't know if that's because the lame was being pushed out the end and once it was off the heat went up the tube at least that was my theory but I'm sure I'm wrong since I've been doing this for about 3 minutes now lol. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted January 3, 2019 Share Posted January 3, 2019 It looks like you need to pull the burner back about 3 inches or so. The end should be well up inside the blanket layer. It's normal for the burner tube to get hot after shutting down if your burner is mounted vertical or nearly vertical. While in use the propane/air mixture constantly cools the burner tube as it pushes the cool fuel/air mixture through the tube. Once you shut the burner off you lose that cooling effect, and the heat inside the forge will tend to rise out of any openings. If you're worried this might damage your burner you can remove it after shutting it off or if you have a choke you can close it all the way so that the hot air has nowhere to go. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 3, 2019 Share Posted January 3, 2019 The chimney effect works for burners that are shut off. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted January 3, 2019 Share Posted January 3, 2019 Yes, but if they have a choke that is completely closed there's nowhere for the air to go, so the effect is significantly diminished. Quote Link to comment Share on other sites More sharing options...
tardster Posted January 3, 2019 Author Share Posted January 3, 2019 ok took the tip off the burner, it was 3" long so I cut half and inch off so by the time the castable is on it should be even or inset so hopefully this will take care of that issue, I hope anyway lol... The burner is 1 of the geode stainless 130000 btu burners off amazon. I tried my hand at building my own but didn't like the way it worked so I figured I'd o with this until I get comfortable enough to do one of Frosty's or Mikey's (whomevers design it is) Tburner. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted January 3, 2019 Share Posted January 3, 2019 If you can pull the burner back further it would be better. The further the end is away from the high heat the longer it will last. Keep in mind that you may have altered the performance of your burner a little bit by cutting the piece off the end. Hopefully it was just a flare on the end of the burner, but even if it was that could still have an impact on the burner performance. Is there a reason you can't pull the burner out further? Since you're still in the building stage you can always make a longer mounting tube on the forge with the set screws further back if they are hitting on the flare end of the burner. I'd much rather see you do that than make any more modifications to the burner you bought. Quote Link to comment Share on other sites More sharing options...
tardster Posted January 3, 2019 Author Share Posted January 3, 2019 Buzzkill, yes that was the flare I cut down. The flare was 3 inches long and with the castable and kaowool that only leaves me 2.5". I can cut a bigger hole in the forge to allow the flare to come through it which would allow me more distance from the castable and the tip of the flare or I could go with 1" of castable which would be easier and have the tip of the flare half an inch from the inside of the castable if that makes since. Quote Link to comment Share on other sites More sharing options...
Another FrankenBurner Posted January 4, 2019 Share Posted January 4, 2019 The hole in that shell should match the inner diameter of your burner mount. The flare and all should fit from the outside. A longer/taller burner mount would allow the flame end of the flare to be just inside the shell of the forge (almost outside the kaowool/refractory). With a longer mount, you could add a second set of mount screws which is nice as you can aim the burner to some extent. If you go through that trouble, you might take a look at forges 101 on the burner angle. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 4, 2019 Share Posted January 4, 2019 22 hours ago, Buzzkill said: Yes, but if they have a choke that is completely closed there's nowhere for the air to go, so the effect is significantly diminished. Yes, but a washer on the outside of the burner's mixing tube will complete that task. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 28, 2022 Share Posted July 28, 2022 (edited) Hi all. New to blacksmithing, made a couple of basic knives in a course, and I'm now trying my hand at forge building. The pictures are the current state (version 3). It's not progressing well. Version 1 had vertical burners with a touch of space (hairline) around them, and the burner tips were recessed about 1 inch from the hot face interior of the forge. In version 1, the burner tips got red hot faster than I could get my steel to forging temp (1600 F). Version 2 was much the same but I sealed off the hairline space around the burners with kaowool and refractory cement, and added a thermocouple. No perceptible change. Maybe bought an extra 3 minutes. Version 3 - I tilted the forge on its side and pulled the burners back pretty far, and sealed the kaowool in the burner ports. Hit 1300 F and a touch of orange started to show on the burner to the right (the black one) at the exterior shell. The other two burners (plumbing ones) were glowing at their tips inside the forge but not outside. I can touch the outside shell of the forge with bare hands in most places during operation, but close to the burners no way. I put some refractory bricks against one of the openings in Version 1 to see if it would have any effect... and it heated up much faster, but I noted the burners got orange faster too. Questions: 1 - ideas on how to fix this? Is it worth trying to fix? Cheapest "good" fix options? 2 - What is the appropriate warning sign that I need to shut it down? I assume that I likely went too far letting the orange start to show at the exterior... But how do I know? 3 - I made the openings smaller than the inside body as kind partially closed doors like a pizza oven... And I made a flat floor which is now a wall... Are these now causing me problems? Thanks x a million folks. Edited July 29, 2022 by Mod30 Resize photos Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted July 29, 2022 Share Posted July 29, 2022 On 1/3/2019 at 2:41 PM, tardster said: ok took the tip off the burner, it was 3" long so I cut half and inch off so by the time the castable is on it should be even or inset so hopefully this will take care of that issue, I hope anyway lol... Maybe. We started out suggesting that people keep their burner's flame retention nozzle 1" inside of the burner opening; in other words, keep one inch away from the flame swirling around inside the forge. Gradually that recommendation has change to placing the end of the flame retention nozzle just inside the forge shell. Why this change? Because we have been improving burner performance, and forge design, so that our forges have become way hotter. So, whether or not what you intend will work out okay will simply depend on how hot you run your forge. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 29, 2022 Share Posted July 29, 2022 Njaak: If you put your general location in the header a member living within visiting distance may be able to give you some hands on help. Are those 3/4" burners in your forge? How many cubic inch volume is it? Please do NOT list the outside dimensions I stopped doing arithmetic for folks years ago, what we need to know is the volume of the chamber in cubic inches. If those are 3/4" burners it's entirely possible you have one too many and back pressure is causing the flame to stay in the burner nozzle rather than the refractory liner. I use a thread protector" as a step "flare" on my burners. I started using them as a sacrificial nozzle to make mounting the burner easy and just tuned for my preferred flame. Later I discovered they were acting as a step flare enhancing performance. Cool. Anyway, the thread protectors turn orange hot after an hour or so and they will burn up after a few dozen sessions. They're sacrificial, they burn up so the more expensive parts don't. I sometimes dip them in a refractory slurry I made up and they last longer. The nozzle on your burner will get HOT, it has a hopefully 3,000f flame shooting out of it. There are some tricks. First barely extend the tip through the forge shell into the refractory. Secondly, make the burner port through the refractory larger than the end of the burner nozzle, if the OD of the nozzle is 1 1/2", make the port 2". Rigidize and apply your hard refractory to the inside of the burner port. If you leave bare refractory blanket you'll first be blowing vitrified refractory into your breathable atmosphere which is a B A D health hazard. Performance wise the blanket will slow the flame and trap part of it in the fibers trapping heat in contact with the nozzle. Those are general rules of thumb if you provide details I can be more specific. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 29, 2022 Share Posted July 29, 2022 (edited) Many thanks I'm in Ottawa Ontario Canada. Yes, 3/4" ID pipe as burner tubes. Two with bell reducers, One with a 1 1/8 ID tube instead of any flare. I would be very interested in thread protectors and will look into getting some. Also thought I could remove the flares entirely and instead cast them into the chamber with Satanite or something like that. Main chamber is approximately 5" ID, 13" long (1021 cubic inches). Front and back ports are approximately 3.5" ID and 3" deep (231 cubic inces between the two). Total roughly 1250 cubic inches plus a little more for the burner port holes. I was worried I had one burner too many, but went with the advice of a local guy down the road from me that does a lot of metalworking... But he's not a blacksmith. If I need to go down to 2, I'll likely just rework the entire thing. Might a ribbon burner sort out my problems? I chose propane burners because my area is windy and I only work outdoors (hence forge on a cart). Thanks again good sir! Edited July 29, 2022 by Mod30 Remove @name tag Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted July 30, 2022 Share Posted July 30, 2022 If wind proves a problem, then a ribbon burner should give you relief. Some guys use small wind screens. I think it just depends on how much wind, times how often it blows, times how irritable you get But ribbon burners all have more wind resistance than other naturally aspirated designs, because of their plenum chambers. Also, ribbon burners can be fan blown, further distancing them from the vagaries of breezes. Still, it's best to try out your forge for a while to see if the problem is easily dealt with, before rebuilding it. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 30, 2022 Share Posted July 30, 2022 Telling us where you are in a post isn't going to stick in anybody's memory once we open a different one, heck after someone else posts in this one. We aren't going to go hunting through back posts to maybe tip you about a good deal at a yard sale or invite you to a get together, etc. If you click on your name or avatar and select "edit Profile" on the upper right, put your general location in the indicated place and save. Your location will be on every one of your posts so all anybody'll need do is look at one of your posts. Make sense? How did you calculate the volume of your forge? Don't worry about exact, how long your doorways are nor the intake ports. What formula did you use? Two 1/2" burners is too much for the actual volume but it's so long and narrow that would be . . . okay. I'd recommend building another forge using one of the many proven designs discussed in Forges 101, Or perhaps a simple brick pile forge. I don't think a wind break will be enough at this point and while a ribbon is more stable in a wind it's a more technically difficult build than a basic forge. Wind breaks are ease as propping up a cookie sheet upwind of the intakes. I'm not trying to discourage you, I'll be more than happy to help but what you built so far has serious problems, please don't think I'm just picking at your build. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 30, 2022 Share Posted July 30, 2022 (edited) Hey Frosty I did that re: location. Not sure why it doesn't show... I'll put up a sketch, but I'm already disassembling it. Volume calculation is just pi*(r*r)*L. Don't and back "openings / doors" have depth to them so I included that in the total. The objective is to be able to forge pieces up to 12" long in a hot zone. The rebuild will allow up to 4" wide. I'd like to be able to do knives, drifts, axe heads, and basic tools. I'll go to the 101 page again. My build was based on one I going in instructables. I did add the constricted openings and third burner, clearly mistakes I think. Thanks again. Edited July 31, 2022 by Mod30 Remove @name tag Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 30, 2022 Share Posted July 30, 2022 It's showing now and will on all your posts past and future. Please don't use the @ tag it conflicts with the Iforge operating software and makes the moderators remove it. This is an internet forum, not a social media site it works differently. No big thing so long as you don't keep doing it, then the mods will go all moderator on you, we ALL prefer to stay under their radar. Check your math you missed the volume by a factor of 4. You can only realistically forge 4-6" at a time without reheating, any more than that heated to forging temperature suffers decarburization, scale loss and grain growth. All B A D for the steel. Stick with us, it takes a good base of knowledge and experience to sort the good from the bad on the internet, some Youtube build videos are down right dangerous. We'll be proud to help get you up and forging. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 30, 2022 Share Posted July 30, 2022 Thanks SO much Frosty. I'll put some sketches together in the coming days for a rebuild and post for critique. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 30, 2022 Share Posted July 30, 2022 I'll be around even if I don't get back the same day. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 31, 2022 Share Posted July 31, 2022 Ok, did some 101 reading and rethinking. My basic cylinder is 5" ID and 19" long. 373 cubic inches. Frosty, I'd used diameter instead of radius in my previous calculation... urgh. Hence the factor of 4 error. Most embarrassing, as some 15 years ago I earned a mechanical engineering degree (that was used for nearly 3 years, before turning my brain to other useful things). I'm flattening the bottom out a bit which will reduce the volume no more than about 1/10 to 1/8. Roughly resulting in say 340 cubic inches. My understanding is the rule of thumb is one 3/4" burner per 250-300 cubic inches. Given I doubt I'm in the highest efficiency build category, I believe 2 burners should work well. They may even be a bit much. My previous design with even less volume (door constrictions) and 3 burners was unfortunately.. really really bad. The pipe reducers on my burners appear to be the worst flares ever. I will remove them and cast my reducers into the build. The 1/12 rule suggests that for my 0.75" ID burners, the entrance diameter at the forge hot face is only marginally bigger. A 1" increase in diameter per 12" length, means that with 2" wool thickness and a 30 degree angle of incidence, I'll build my mold about 6" long with one end at 0.75" diameter and the other at 1.25" diameter and cast around it. I'm also reconsidering my use of a threaded burner support bar. I did so because I don't yet weld, but do plenty of threading. However, the extra steel adds weight and fuss. I may either pay someone to weld it up, or knuckle down, take a step back, and learn to weld. Some pics of my rough sketches and math for critique. Thanks all! Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted July 31, 2022 Share Posted July 31, 2022 34 minutes ago, Njaak said: I may either pay someone to weld it up, or knuckle down, take a step back, and learn to weld. If you keep the tolerances tight (maximum of 0.005" gaps), nothing prevents you from employing one of those burners to silver braze parts onto the forge shell. Quote Link to comment Share on other sites More sharing options...
Njaak Posted July 31, 2022 Share Posted July 31, 2022 Mikey that sounds harder than picking up a MIG welder and learning how to use it LOL Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted July 31, 2022 Share Posted July 31, 2022 The advantage of silver brazing is that, while fussy, all the work is in preparation. Unlike hard brazing (AKA braze welding,)no skill is needed to do the deed Quote Link to comment Share on other sites More sharing options...
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