Trip Posted January 25, 2012 Share Posted January 25, 2012 I have been setting up my new shop, and I even built a new masonry forge!!!!! But with the lay out of my new shop I will have to use an over head forge hood, but since I have always used a side draft hood I have no idea on how to build one. My forge is 4'X4.5', and I plan on using a 12" pipe. So does the hood need to be the same size as the forge? How tall? How far from the top of the of the forge to the bottom of the hood? Thanks to all, Trip Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted January 25, 2012 Share Posted January 25, 2012 My first forge had an overhead hood and I did not like it...there is good reason why many folks go with side drafts. However, if you are stuck with that choice, make it the hood the size mentioned in your post (4' square) and use the 12" flue. I had a buddy in the HVAC business brake the flue from a standard 4x8 sheet of galvanized and the hood had a 12" square hole to match the flue. In addition, I hung a separate piece of sheet metal on the back side and left edge of the hood (as facing the forge) that was as wide as the hearth and almost touching the forge. This is important because the piece will heat up and cause most of the smoke to draft into the hood. If you don't have something to induce good draft, the smoke will typically waft around and fill the shop. One of the best exhaust systems I ever saw was in a shop about 30 years ago. The smith had high ceilings and a big exhaust fan in one gable near the peak. He could turn on the fan and create a vacuum in the building that would pull any ambient smoke out of sight so his forge had no hood. Quote Link to comment Share on other sites More sharing options...
FieryFurnace Posted January 25, 2012 Share Posted January 25, 2012 One of the best exhaust systems I ever saw was in a shop about 30 years ago. The smith had high ceilings and a big exhaust fan in one gable near the peak. He could turn on the fan and create a vacuum in the building that would pull any ambient smoke out of sight so his forge had no hood. Good plan! I like it! Easy to remember! Seriously, the extra two pieces on the side of the hood hanging down to the forge were a good idea. That seems like it would help alot! P.S. You have to post pics of your forge-in-progress. Forum "rules." :D Quote Link to comment Share on other sites More sharing options...
Trip Posted January 25, 2012 Author Share Posted January 25, 2012 Thanks for the info. OHHHH and about the forge in progress. That's a WHOLE nother topic for when it is FINISHED!!! LOL Quote Link to comment Share on other sites More sharing options...
SmoothBore Posted January 25, 2012 Share Posted January 25, 2012 For what it's worth ..... During the time when I worked in the Wire & Cable business, OSHA required the Company to install overhead hoods at all the Plastic Extruders, that were used to extrude the "Poly" jacket, found on most electrical cable.( The fumes from burning Poly-olefin, Poly-urethane, Poly-styrene and many other Plastic Compounds, are VERY toxic. ) In order to effectively capture the Toxic Fumes that were emitted by the molten plastic, the hoods needed to fit right down, very closely over the extruder heads.This, of course, interfered with the setup, operation and maintenance of the extruders. The solution was to make the "flue pipe" telescope vertically. This was accomplished quite simply, effectively and inexpensively, by forming a 5' long section of "stove pipe", that was slightly smaller than the standard size pipe, that was used for the rest of the 35' vertical rise flue. The undersize pipe was mounted directly to the top of the hood, ... and the hood was raised and lowered with a hand cranked "boat winch", and a simple system of cables and pulleys. These hoods were so simple and "user friendly" that we ended up building 14 of them for "in plant" use, and an equal number, for another "Sister Plant" in Indiana. I describe all of this, because a fairly low hood over your Forge, will be the most effective for removing smoke, ... but there are times when it will be in the way. And there might also be times when the ability to lower the hood all the way down onto the hearth, would be useful, as well. . Quote Link to comment Share on other sites More sharing options...
eric sprado Posted January 25, 2012 Share Posted January 25, 2012 Here is a site that discusses forge chimneys in depth: http://www.beautifuliron.com/chimneys.htm Lots of good info. Good Luck Quote Link to comment Share on other sites More sharing options...
Randy Posted January 25, 2012 Share Posted January 25, 2012 Some how I don't see this. Guess I just dislike hoods so much. Why can't you do something so you can still use the side draft? Quote Link to comment Share on other sites More sharing options...
Marksnagel Posted January 25, 2012 Share Posted January 25, 2012 I'm about to move my forge inside this weekend. Still don't know what I'm going to do for exhaust. That was a great link Eric, thanks. There is also a lot of good info right here on IFI. Can't have too much info I reckon. Quote Link to comment Share on other sites More sharing options...
Trip Posted January 25, 2012 Author Share Posted January 25, 2012 Hey y'all, thanks for the input, it has given me room for thought. The reasone I am considering an over head hood rather than a side draft is because my forge is about 6' away from the nearest wall. Also I had a Uri Hoffi style side draft in my last shop and it would smoke up the shop to kingdom come!!! I was using a 12" flue pipe too. Also I like the idea of the djustable height, but it seems like that unless you used chain and gears, the hood would stay "lop sided". Quote Link to comment Share on other sites More sharing options...
Old N Rusty Posted January 25, 2012 Share Posted January 25, 2012 I have a 12" pipe suspended directly over the firepot. 12" (adjustable height) over the forge. It is 20' long and 6' is above the roof ridge. The thing draws dust from the air even when I have no fire in the forge! there is no hood for head banging, or sides to get in the way of working all around the forge. The pipe is sch.10- 316 stainless steel and will never rust. Quote Link to comment Share on other sites More sharing options...
HWHII Posted January 25, 2012 Share Posted January 25, 2012 I have been in a shop where they cut a 55 gal. drum in half and hug it over the forge. Looked like it worked good for them Quote Link to comment Share on other sites More sharing options...
Marksnagel Posted January 25, 2012 Share Posted January 25, 2012 I have been in a shop where they cut a 55 gal. drum in half and hug it over the forge. Looked like it worked good for them Cut lengthwise (end to end) or around the middle? Quote Link to comment Share on other sites More sharing options...
HWHII Posted January 25, 2012 Share Posted January 25, 2012 Cut lengthwise (end to end) or around the middle? Around the middle. I have also seen 55 drum with a arch cut in it and used as a side draft hood on a flat table forge. Quote Link to comment Share on other sites More sharing options...
Trip Posted January 25, 2012 Author Share Posted January 25, 2012 Hey yall thanks for all the idea's. After hearing yall say "NOOOO" to an over head design, I am thinking of doing a masonry side draft. The reason behind building it out of brick is because I am building a masonry forge, here is a link so that you can see what it looks like at this time. http://s1109.photobucket.com/albums/h422/kyblacksmith/ I plan on facing it with stone or brick, and I am going to put a 1/2" thick top on it, with a hole cut out of the center for the fire pot. Quote Link to comment Share on other sites More sharing options...
Drewed Posted January 25, 2012 Share Posted January 25, 2012 Your smoke shelf looks too low and to sharply angled. If your plan is to scale. The shelf should be above the top of the opening Quote Link to comment Share on other sites More sharing options...
Trip Posted January 26, 2012 Author Share Posted January 26, 2012 Do yall know where I can find 12" stainless steel pipe? I have used galvanized pipe before,but this time I am worryed that the pip will be to close to the fire. Quote Link to comment Share on other sites More sharing options...
musk-rat Posted January 27, 2012 Share Posted January 27, 2012 I know Mcmaster has 10" but it is expensive. I have got a lot of stuff from this place when no one else locally has had it. http://www.krootcorp.com/ I think they are about 2 hours from you maybe. Quote Link to comment Share on other sites More sharing options...
humphreymachine Posted January 28, 2012 Share Posted January 28, 2012 I had a fantasy of the suspended industrial style forge hood open on all sides but like others here found that the draw was poor. After much experimentation I found that adding tin on three sides was the only way to achieve a smokeless shop. The rear shield is the only fixed piece. The front hinges upward(its upper edge is INSIDE the hood when closed) and the two pieces on the forge’s right side are held in place by the coal/coke and are easily removed for heating longer pieces of iron. While not super attractive, I now have a smokeless shop except for the few wisps which escape when first lighting. The hotter the fire the better the draw and when the work merits a hot fire the front shield can be lifted up and the side panels removed and still no smoke in he shop.The chimney pipe is ten inches in diameter and has proven capable of drawing all fumes and smoke even when the blower in running at full capacity. The hood was a recycled piece of sheet metal ducting I was luck to scrounge—though it probably would be preferable to have the hood slope uniformly up to the chimney rather than flat on top like mine. The sketch I included is an idea I had for a removable shroud to use when a small fire is all that is needed when using a forge with a telescoping hood. The shroud could be placed directly on the coal and the hood lowered down to mate with it. I haven’t tried it but it may work for small low draft fires? I have never seen a side draft hood in use but question how they can possibly work effectively when really cranking the blower to heat thick stock? Seems like the blower pressure would force smoke and fumes in directions other than sideways into the chimney? Quote Link to comment Share on other sites More sharing options...
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