Everything Mac Posted June 19, 2013 Share Posted June 19, 2013 Hi guys, I'm building a new firepot for a forge upgrade and just a quick question... My welding is pretty naff so I was wondering if I should put some on the underside of the lip going around the pot? I'm not sure if one layer will hold it once the heat is up? The pot is 10mm plate and annoyingly I managed to weld it up slightly squint. The welds aren't the best at all but seems to work ok. I also had issues with my hole saw and ended up having to drill lots of small holes to get it out. I've used what was left as an initial air inlet. It's pretty ugly and I will replace it eventually. I've enough of the plate left to use it as the table for the forge. Cheers Quote Link to comment Share on other sites More sharing options...
PaulKrzysz Posted June 19, 2013 Share Posted June 19, 2013 What are the dimensions of the pot? How thick is it? Paul Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted June 19, 2013 Author Share Posted June 19, 2013 10mm thick. 8x12" around the top, 5x6" at the bottom. With a 2" air inlet. Cheers Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 19, 2013 Share Posted June 19, 2013 There are a couple ways to reinforce the join between the fire pot and the table if you feel it's necessary. The first would've been to make the fire pot wedge just slightly before it rests on the lip. To do this now, you can weld some thin strips around the pot under the lip so it's large enough to wedge a LITTLE. You'll probably have to tap it out from below to remove it. Welding a bead inside the angle of the flange and pot will enlarge it too but I'm not fond of that kind of wedging. Then is whether what you've done is worth worrying about. Are you going to be putting something IN the pot heavy enough to break the flange welds? Seriously, it only needs to support a load of coal and your work, heavy stuff is going to be laying on the table with an end or middle in the fire so the post isn't supporting anything but the fire. Seriously, it's not like you're going to be heating a 70lb. cannon ball are you? Standing a heavy shaft on end to heat the end are you? I'm pretty sure it'll support 10+lbs so it's not worth messing with. With what I can see this is my advice to you. The rest is me being my usual windy self. <wink> For practical, take a hammer and give the flanges a couple whacks, if one fails clean the join and reweld it. When I say whacks I don't mean take a home run swing at it with a 4lb hammer, you're only trying to apply a hundred lbs. of force in a shock loading situation. This is FAR worse than will happen to it in any normal use. In the future, welding flanges like this align the steel in the join so one side protrudes about half it's thickness above the other. This will concentrate more heat in the join but the protruding bit will supply the additional filler and seeing as half the join is melting beyond normal penetration without the downside it'll make an easier to achieve solid weld. If the stock is 1/4" or above align the joins so the edges don't quite meet by half the stocks thickness, weld it there. Make these kinds of welds on the OUTSIDE of the join angle. Another method I like is to use the end of a welding rod spacer to make an open gap in the join. It makes penetration easier without having to grind a scarf but you do need to know how to keep from burning through. Practice practice, etc. Trying to fill the inside of an angle join makes it harder to get good penetration and takes practice beyond most folks home welding experience. NO, over amping the rod isn't a good technique, it may leave a pretty weld but a good weld is WAY preferable. End windy ramble and I bow humbly to the welding instructors here. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted June 19, 2013 Author Share Posted June 19, 2013 Thanks Frosty. That's not the first time you've been kind enough to take the time to write a very helpful reply for me. Kindly have an imaginary beer on me. Much appreciated Andy Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 19, 2013 Share Posted June 19, 2013 OOOH, a fulsome English ale, consider it quaffed! I enjoy passing on what I've learned, I spent a number of years learning fabrication and welding but only practiced the trade a short time. Till I discovered how quickly welders seemed to succumb to occupational hazards, mostly metal poisoning and UV burn cancers. Yeah I took my training before welding smoke was considered a hazard and the guys tigging the inside of milk trucks used to do it nude with really tiny shade 12 goggles to get a killer tan. Ah, I'm getting all windy again. Truth is I like helping folk, it makes me feel good, I often help folk load groceries lumber, whatever just to earn a smile. I learned about how good being randomly helpful makes me feel one Christmas, the story is unimportant. Anyway, I discovered making others feel good made me feel good and got me over depression better than anything else I'd ever tried. I can be manic but on the rare occasions I feel depressed I go to the mall and just do things for people and it fixes me. Sharing what I've learned is sort of a maintenance dose of nice and keeps me in a generally good mood. Funny how something that makes you feel good rapidly becomes habit forming eh? Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Farmweld Posted June 19, 2013 Share Posted June 19, 2013 I had a steel tuyere similar to what you have welded up and the worst problem I had was that whenever I had a big fire running in it it would start eating the sides of the tuyere. Mine was 10mm plate backed with sand and I managed to burn one side out after about three months of firing it up 2-3 times a week. The mild steel plate doesn't seem to have the longevity when it is in direct contact with the fire. I have another forge that has a 10mm Bisalloy plate in the bottom of it and that doesn't seem to be affected by the fire at all. Let us know how you get on with your forge after you have used it for a while. Andrew Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 20, 2013 Share Posted June 20, 2013 The fire would start eating the TUYERE? You're not talking about a side blast are you? Side blast forges tend to bur up tuyeres. A bottom blast tuyere isn't or shouldn't be near the fire and the air flowing through it should keep it cool enough to last for a long LONG time. Generations maybe. OR are you talking about large fire eating the fire pot? If it is actually eating the tuyere please describe your forge how it's built and what conditions cause it to eat the tuyere. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted June 20, 2013 Author Share Posted June 20, 2013 Hmm, I'd like to see pictures of what you mean Farmweld, if possible? This is why I decided to go for a sacrificial tuyere at this point. It just drops in, and can be taken out and replaced at will. Perhaps once the forge is properly up and running I will design and build a clinker breaker to go in there. I plan on lining at least the bottom of the firepot with a firebrick. It's like,y I will line the sides too. Cheers Quote Link to comment Share on other sites More sharing options...
John McPherson Posted June 20, 2013 Share Posted June 20, 2013 I think we may have found the problem: "10mm plate backed with sand" DO NOT insulate the sides of the firepot or air tubes below it, it needs to have enough clear space to allow radiation and air circulation to keep it from burning up. It can glow cherry red and still be just fine for decades, as long as you do not use water on it while hot. Water on hot metal has destroyed more forges than heat ever will. In heavy use it may get hot enough to scorch your legs, or char wood or paper within 24 inches, but that will not hurt the forge. Quote Link to comment Share on other sites More sharing options...
IronHide Posted June 21, 2013 Share Posted June 21, 2013 May I ask at what amperage setting you are welding and what type of rod you are using. It looks to me like you are much to cold, at the right temperature using a 7018 (CSA 4918) rod and welding in the flat position it should pretty much weld itself. If you have an amperage gauge on your machine here is a list of starting points for welding. 3/32 7018 80-110amps start around 90 1/8 7018 110-140 amps start around 125 5/32 7018 150-190 amps start around 165 I wouldn't use a rod much bigger than those, if you don't have a gauge you can set your heat by taking a piece of scrap steel, set your heat and fire in, pull a bit of an arc and let your puddle establish, slowly lower your rod point if it snuffs out you are to cold. Go up 5 amps and try again, when you can drive the rod into the puddle without it snuffing out you are at the right temp, with enough practice and a machine with an arc force setting I can drive a 1/8 7018 through a 1/4 piece of steel no problem. If you have any questions on welding or proper techniques don't be afraid to PM me, I'm new to the forum but I'm a welder by trade and can weld anything from the crack of dawn, to the crack of your butt :D Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted June 28, 2013 Author Share Posted June 28, 2013 I'm not using a rod. I'm mig welding. Amps were set quite high but not to the max. Cheers Andy Quote Link to comment Share on other sites More sharing options...
Joel OF Posted July 5, 2013 Share Posted July 5, 2013 Just a by-the-by Andy...when drilling thick steel with a hole saw, to make life easier and avoid getting the slug stuck in the saw, don't drill all the way through in one hit. Drill in about 3mm with the hole saw, then when it gets to be a bit of a pain because the "waste" (brain freeze, can't think of a better word), hasn't got anywhere to go, drill a bunch of regular holes, say 6mm, where you've just marked with the hole saw, then go back to the hole saw. That way the "waste" has got somewhere to fall through + you've already got the holes you need in the slug to pull it out if it's stuck in. The slug at the end will be round like the hole saw, but it'll have semi-circular or near circular holes at the edges where you drilled through with a regualar bit. Get it? That's just something I came across before I made my firepot, saved me a load of grief as all I had was an electric hand drill, no pillar drill. Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted July 5, 2013 Author Share Posted July 5, 2013 Cheers. I ended up doing that anyway. The hole saw I got died not even halfway through the plate. Wasn't impressed. :/ Andy Quote Link to comment Share on other sites More sharing options...
Joel OF Posted July 5, 2013 Share Posted July 5, 2013 Going by your picture of the slug with all the holes in it, that's not what I mean. I mean drilling holes where the hole saw is cutting, not inside where the saw is cutting. Unless you do that sorta thing I think hole saws can only really go down about 3mm in steel - or that's what the shops will say the spec is anyway. With regards to the welding underneath, I did with mine but I don't think it was neccessary afterall, I just did it because I'm a complete novice at welding and I just wanted to have it belt and braces. What's that saying? "If you can't do knots, do lots." Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted July 5, 2013 Author Share Posted July 5, 2013 No I understood you perfectly. I drilled numerous 4mm holes in the slot cut by the hole saw, enough to cut the hole out as the hole saw had given up by this point. The larger holes you see above were drilled after I'd managed to cut out the disc from the steel. Cheers Quote Link to comment Share on other sites More sharing options...
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