harmvdw Posted June 26, 2019 Share Posted June 26, 2019 Hi everyone, I have made a forge with a nice burner, only i do not seem to get the temperature high enough to forge weld. I have two square bars of 12mm which i want to forge weld. Why?? Well the last time i welded(25 years ago) i made some fire pokers (don't know if you write it like this) and thought it would be a nice project to start with. Only the last time i welde on coal in stead of a gas forge. Here are some photo's and films The inside size of my forge is, 220mm (8,5 inch) deep 160mm (6inch) wide and 110mm (4,5 inch) high. My pressure is aroud 0,55 bar (8psi) The bricks 1 use are 30mm think and my insulation is 40 an 50mm think. Should i increase my pressure? And now i think of it maybe i should insulate the bottom, would that make a lot of difference? I someone has some hints that would be nice. I have searched the forum but there is so much information i just don't know it anymore. Kind regards Harm Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 26, 2019 Share Posted June 26, 2019 We'd need more information to make a good suggestion Harm. How much pressure you feed a burner isn't a good indicator if it's working properly, there are a number of variables that alter it better pressure. A few pictures of your forge running will help: A picture in the door while it's still cold so we can see what the flame looks like. Then a pic or two when the forge is hot and lastly a pic or two across the door so we can see what the exhaust looks like. We call it Dragon's breath. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 26, 2019 Share Posted June 26, 2019 Your photos and video show the work getting hot enough to weld. But they also show conditions that make it likely to be a struggle. Your forge design and its bricks could use more tweaking, but are not your main problem; your burner is. The burner's flame is way too soft (cold) and HEAVILY reducing. The exhaust flame (dragon's breath) is large and also blue. Much of your fuel is being vented as carbon monoxide into your shop air, instead of producing heat in your forge. I'm sorry, but you would be well advised to start over with a different burner--after finding out how to build one properly--or after buying one of the reasonably priced import burners off of eBay. Quote Link to comment Share on other sites More sharing options...
Goods Posted June 26, 2019 Share Posted June 26, 2019 Just an observation, you may want remove the brass coupler from the “T” fitting. That should help induce more air. Quote Link to comment Share on other sites More sharing options...
harmvdw Posted June 27, 2019 Author Share Posted June 27, 2019 Oke, thanks for the answers, Frosty:, i will take some pictures this weekend as you mentioned and post them. Goods: I will take out the coupler and see what happens. Mikey98118: on the picture's everything looks brighter then in real live, so this is a bit misleading. The pictures where they look bright yellow/white are in real light orange. I will also go deeper in to the burner design basics. A update will follow this weekend. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 27, 2019 Share Posted June 27, 2019 If you've already posted pictures I'll go back and take a look. No need to post them again. Tagging people's names in the response causes problems for the Forum software, you'll make the mods a LOT happier if you leave the @ out and just type our name. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
harmvdw Posted June 27, 2019 Author Share Posted June 27, 2019 That are only photo's from when it is hot. I will leave out the @ sorry Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 27, 2019 Share Posted June 27, 2019 No need to apologize there's always something to learn about using this forum, it changes often. We tell each other when we're making a mistake all the time. We're family we don't let family make mistakes without telling them. The first photo shows the burner running before the forge is hot, this is good it lets us see what the flame looks like without the details being washed out by the hot forge. The long opaque light blue flame tells me it's burning very rich, not enough air. Lose the brass fitting and anything else you have the air intake ports in the T. If it sounds like I just said the same things Mike and Goods did it's because we all see the same issues that need correction. You're right about photos making HOT things look hotter than they are. However that is plenty hot enough to weld if it's a known steel and not to odd a weld joint. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
harmvdw Posted June 27, 2019 Author Share Posted June 27, 2019 Oke, I will get the brass fitting out and try again. The steel i have lying is "normal" steel sj235. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 27, 2019 Share Posted June 27, 2019 I had to look up the steel and it's roughly equivalent to American structural steel, a bit more special than what we call mild or A36 steel. Close enough. We'll help you get your burner tuned, it just needs some adjustments. No problem. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 27, 2019 Share Posted June 27, 2019 On the other hand, once your burner is running right, you may need to add a protective coating to that brick; it looks like the kind used for fireplaces? If so, the brick isn't intended to deal with a gas flame's heat... Quote Link to comment Share on other sites More sharing options...
harmvdw Posted July 2, 2019 Author Share Posted July 2, 2019 Hi, I have edited my forge and I am almost there, it's already yellow hot. It is "smooshie" but not just sticking together yet. I have removed the brass plug and put the insulation under the forge. I have read more on the forum but i still do not understand how i can make it better, there is just to much information for me to understand. I have made pictures and movies while it was cold. The flame is looking "nice" i think a little bit rich if I am nog mistaken. I am using a 0.03 (0,8mm) mig tip. @ mikey: I know i need a protective coating, but i first want it running good before making something that is not easy to alter. I am using "pizzaoven bricks" the specs say they can take 1750 degrees Celsius, probably not meant for open flame, but i have to check that. So i someone has some more tips i would really like to hear them. Kind regards from the Netherlands Quote Link to comment Share on other sites More sharing options...
Chris C Posted July 2, 2019 Share Posted July 2, 2019 K26 or M26 soft insulating bricks with a Kast-O-Lite coating will do much to improve your forges long term capabilities, harmvdw. They withstand 2600 degrees. The Kast-O-Lite protects the bricks from the flux used to forge weld. I can't help you much beyond that because I'm still in the process of building my forge and I'm just passing on what I've been told. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 2, 2019 Share Posted July 2, 2019 If you wish to lean the flame out moving the jet back from the mixing tube will cause it to entrain more air. I can't tell if you can just loosen it and pull it back, if so mark where it is now, it's close you might want to return it to this ratio. If you can't move it back, you can trim a LITTLE off the end of the mig tip jet. By a little I mean 1-2 mm. at a time and test. You'll need a torch tip cleaner to deburr the orifice. I find a fine single cut file or fine sand paper works well to shorten mig tips. I don't tune burners like Mike but I've had good results. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted July 3, 2019 Share Posted July 3, 2019 21 hours ago, harmvdw said: I am using "pizza oven bricks" the specs say they can take 1750 degrees Celsius, probably not meant for open flame, but i have to check that. How much heat the bricks can withstand is only one aspect. Another aspect is how much heat they absorb and/or transfer. I'm sure you would expect a piece of steel that is 3 inches thick to take more time to heat up than another piece of the same steel that is only a half inch thick. The same principle applies to your forge floor and walls. A thick, dense, non-insulating material will require significantly more heat (fuel burned) and a lot more time in order to bring your forge up to temperature than a thinner layer of insulating material. It looks like you're using what we call split fire brick here, which is hard, non insulating bricks used for fireplaces or ovens and is 1/2 the thickness of a full sized brick. Those still have a lot of mass to heat up. The insulation layer around the bricks will help hold heat in your forge, but it will still require a lot of fuel and time compared to other options. In the last batch of pictures your burner is still running quite fuel rich, and rich flames tend to be cooler than neutral or lean flames. As Frosty said, you can bring in more air by trimming the mig tip back a little at a time. If it were my forge and burner I'd probably try one size smaller mig tip first to see if that produced a neutral or lean flame. If you go with a smaller mig tip and the flame is still fuel rich then the current tip may not be able to entrain enough air with your configuration. Quote Link to comment Share on other sites More sharing options...
harmvdw Posted July 3, 2019 Author Share Posted July 3, 2019 Oke, my mig tip can't be moved so i shortened it, only i shortened too much so i had to reduce the air flow to get it running constant instead of pulsating. But it was after some tweaking still not hot enough, then i ran out of "play time" i will give it another try tomorrow . The advantage of having to restrict my airflow is that I now can adjust it, see photo with the valve i attached. I have searched for smaller tips at work but the smallest is the one I have. Yes the bricks are very hard, it is almost impossible to drill through (luckily i have a waterjet at work) what is a long time to heat up? i have no idea how long it should last to heat up approximately. I have the feeling i am coming very close but still not there yet. So if i understand correct a neutral or even lean flame is hotter the a rich one, that is good to know, so i can even run it even a bit lean to get to the higher temperature. Thanks for the advice, I will post my progression tomorrow (i hope) Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted July 3, 2019 Share Posted July 3, 2019 It is common for these types of burners to blow the flame off the end when the forge is cold at moderate to high pressure. You should not try to judge the appropriate amount of air compared to fuel by how well the flame stays lit. A combination of flame color and the color of the dragon's breath at the exhaust openings will help you determine if you have a fuel rich mixture. In all of the pictures/videos I've seen of your forge the flames at the exhaust port are always completely blue. That is an indication of too much fuel (or not enough air). A fuel rich flame will stay on the end of the burner better than a neutral or lean flame. That does not make it desirable. A flare on the end of the mixing tube of the burner will help with flame retention. Otherwise you may have to stay at low propane pressure to keep the flame lit until the forge heats up. Once the interior is glowing you should not have any problems with the flame blowing off the end of the burner. What is a "long time" to heat up is somewhat subjective. Your specific burner and forge construction play major roles here. A very well constructed and insulated forge with an undersized burner will still take a while to come up to heat, whereas a poorly insulated forge with a monster burner may come up to heat significantly faster I like to be forging within 15 minutes of firing up the forge. I run a higher pressure while the forge is heating up than I do to maintain the heat once I have the temperature where I want it. If I will be forge welding it will take about another 10 minutes or so at higher pressure to get the heat I want. That's with my setup, but I can guarantee you that there are people on here who require less time for the same results and some who require more time. However, no matter what else is true, the more mass you have to bring up to temperature, the more fuel it will take to do so. In general we do not want to run lean (oxidizing) flames in our forges as that causes scale to form on the surface of the steel while it is still in the forge. It will also decrease the carbon content of the steel faster than a neutral or fuel rich burn. In addition to all that, forge welding can be more difficult due to the oxidation of the mating surfaces, although that can be counteracted with flux to a large degree. Quote Link to comment Share on other sites More sharing options...
harmvdw Posted July 9, 2019 Author Share Posted July 9, 2019 Hi all, Buzzkill: Thanks for the long answer and advice, 15 minutes is about the time my forge heats up so that's about "right". I have once again had some playtime, i have tested my forge again and have com to the conclusion my tip is still to long. After heating up the flame is still blue it is getting less blue but not yet green with all air openings open. So tomorrow i wille shorten the tip even more, so i can run a lean flame and then tune it back to optimum. Silly question, would it help to have two burners in the forge? I see it a lot on youtube and pictures but could not really find a answer if it helps to get "easier" to welding temperature. thanks so far for all the advice. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted July 9, 2019 Share Posted July 9, 2019 On the multiple burner question, the answer is "yes, no, maybe" depending on some specifics. There is more than one reason a forge can't reach or maintain welding heat. Perhaps the most important is the burner. Regardless of how well your forge is constructed and insulated, if the burner isn't tuned properly so that the flames will reach forge welding heat, then adding another identical burner will not help you get to forge welding temperature. So, the starting point is to have a burner which is capable of producing flames hot enough to forge weld. If you have a well tuned burner that can reach forge welding temperatures but you have a poorly constructed/insulated forge, or if the forge volume is too much for the burner to handle, then adding another burner will help get you there and keep you there. To save fuel you may only want to run multiple burners while bringing the forge up to temperature or forge welding, but use only one burner for general forging once the forge is hot. A general guideline is to use one 3/4 inch diameter well tuned burner per 350 cubic inches of well-insulated forge volume to reach forge welding temperatures. I estimate your forge volume at approximately 230 cubic inches, so if you are using a 3/4 inch diameter mixing tube on your burner there should be no trouble reaching welding heat once your burner is tuned properly. In fact, you may be able to get by with an even smaller burner. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.