falsevacuum Posted July 30, 2015 Share Posted July 30, 2015 Hi everyone,I've read time and time again that flue diameter should be 10"-12". However, the half hood my forge came with was a 6". I'm very new to the whole metalworking thing and I'm not sure how I'd go about making a half hood. Nor where I'd get that much continuous sheet metal within an hour's driving distance. Also, I don't have all that much free time, so as much as possible, I'd much rather spend it learning to forge than upgrading my forge.My setup is outside and not meant to be permanent, so installing a side draft or similar is not an option.Right now, I have the half hood set up with about 2' of flue, and that sucks up about 1/2 - 3/4 of the smoke depending on where I'm coking coal. I have another 10' of pipe and a tall cap (opening >6") I plan to install once I get some rebar to support it with.Will I be alright sticking with a 6" flue? Is it just not worth my time?I don't have pictures right now, but I can take and post some tomorrow evening if that would be helpful.Thanks! Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 30, 2015 Share Posted July 30, 2015 Are YOU happy with how it's working? If so it's fine. Are YOU unhappy with how it's working? If so it's terrible, change it! I don't have a hood at all on my outdoor forge and haven't for 34 years of forging; sometimes I wish I did, mostly it hasn't been a problem. Your Mileage May Differ... Quote Link to comment Share on other sites More sharing options...
falsevacuum Posted July 30, 2015 Author Share Posted July 30, 2015 (edited) Well, I'm not happy with all the smoke I'm breathing in. I'm hoping raising the flue height will improve that, but to be more clear I'm trying to ask if you all think I'll see a substantial decrease in stray smoke by raising my chimney or if 6" diameter flue simply can't capture the smoke of a coal fire. Edit: also I'm using a hand crank blower so I'm standing very close to the fire. Moreover I can't leave the smoke without stopping cranking Edited July 30, 2015 by falsevacuum Quote Link to comment Share on other sites More sharing options...
JME1149 Posted July 30, 2015 Share Posted July 30, 2015 A picture or two of your particular setup would help get more informed answers. An outdoor setup is going to be subject to wind which will alter the flow. Just getting 1/2 the smoke up and away is good. Adding another 10 feet may be enough to topple your forge. Personally, I'd try adding another 2 feet and see if it helps significantly, my guess is that what you have may be about the best you're going to get. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 30, 2015 Share Posted July 30, 2015 not knowing the details of your forge means we can only guess. How high is the flue opening off the forge? How much enclosure do you have? Etc. Quote Link to comment Share on other sites More sharing options...
Glenn Posted July 30, 2015 Share Posted July 30, 2015 (edited) With the same side draft hood, in the same location, with the same forge. 6 inch diameter stack did not have enough volume to move much smoke. 8, 10, 12 inch did much better. 14, 16, 18 did not do as well as the 10 inch.I currently use a 24 inch chimney built specifically around the forge that is in use. It works very well.You DO NOT need a hood or chimney to use a forge. A breeze or slight wind will work very well in keeping your work area free of smoke. No wind works well as the smoke goes straight up on its own.The hood should be designed to collect the smoke and the chimney should remove the smoke from the work ares. Use the materials at hand and design a system that works for you. Edited July 30, 2015 by Glenn Quote Link to comment Share on other sites More sharing options...
arkie Posted July 31, 2015 Share Posted July 31, 2015 If adding a larger or higher chimney is not practical, consider putting a fan behind you to blow the forge smoke away from you, It usually takes only a gentle breeze from it to blow most of the smoke away from you (can keep you cooler, also). The only problem with a fan behind you is that in winter, it's not very comfortable!! Quote Link to comment Share on other sites More sharing options...
matto Posted July 31, 2015 Share Posted July 31, 2015 Adding hight will help. Plus setup with the wind or a shield blocking the wind will help to Quote Link to comment Share on other sites More sharing options...
ironwolfforgeca Posted July 31, 2015 Share Posted July 31, 2015 another Idea ? depending on what you need my shop forge 3'x3' with side draft hood & 14" pipe to the outside of the shop wall & then straight up with 8" pipe with a fan in the stack---hence power draft NO smoke problem LOLPS -- also takes the extra Heat out of the working area nice & cool sort of LOL Ok so on the north coast the rest of you need to bring a jacket Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 31, 2015 Share Posted July 31, 2015 Nothing like a day long demo with you the only smith and the heat index over 110 degF to make you appreciate "Blacksmiths Air Conditioning: you step away from the forge and it's cool!" Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted July 31, 2015 Share Posted July 31, 2015 Fire management helps a lot with smoke, but 6" is small. With a real small prtable one might consider building a separate free standing stack so as not to topple the forge. Quote Link to comment Share on other sites More sharing options...
falsevacuum Posted August 1, 2015 Author Share Posted August 1, 2015 (edited) I'm liking the sound of a pipe with a fan in it. How far up should the fan be? A fan nearby would definitely be no fun in the winter! It gets chilly here. I am very worried about structural stability. No problems with the current setup but I bet too much taller and it's liable to topple. I also need to find a setup that doesnt interfere with my path to the anvil. The separate stack might be a good idea (then I can just set it down after use) Edited August 1, 2015 by falsevacuum Quote Link to comment Share on other sites More sharing options...
jeremy k Posted August 1, 2015 Share Posted August 1, 2015 Forget the fan inside the pipe idea and modify the hood with a larger (and taller) diameter pipe - 10" minimum. Quote Link to comment Share on other sites More sharing options...
falsevacuum Posted August 1, 2015 Author Share Posted August 1, 2015 Forget the fan and modify the hood with a larger (and taller) diameter pipe - 10" minimum.I covered the reasons why Im not inclined to do this in the first line of my first post. Quote Link to comment Share on other sites More sharing options...
jeremy k Posted August 1, 2015 Share Posted August 1, 2015 Then you would be better off just removing the whole hood assembly, as it is not working properly due to the size of the flue. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted August 1, 2015 Share Posted August 1, 2015 Not many fans tolerate heat and smoke. Honestly one 3' joint of 10-12" will help emencly. (Or two 6" ziped together in to one 12") but learning to keep the "grean smoke to a minimum with fire management will help a bunch. Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 1, 2015 Share Posted August 1, 2015 You can stabilize the stack by wiring or hose clamping a piece or two of rod to it. Run it from a couple C clamps on the forge pan and up the stack. Not pretty but works. And no it doesn't need to be heavy material, here I'd use some 3/4" angle iron a picked up a couple years ago and that'd be heavier than necessary.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Jawa Posted October 8, 2015 Share Posted October 8, 2015 Have you tried holding a piece of burning newspaper under the pipe it as you're getting the fire started, to help create the draft? Quote Link to comment Share on other sites More sharing options...
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