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And as to why stone weapons were still used instead of metal n the Americas on European contact- even in the South American areas where overall metalworking sophistication was probably on par with Europe's, albeit in a very different way- it seems to come down to there simply being no good reason to switch. The entrenched exploitation and trade distribution of knappable stone, plus being at the absolute pinnacle of stone-knapping skill/ability and the much lower cost of stone tools, precluded that. Bronze tools and blades have absolutely been found in South America and were clearly in fairly general use, they just never unseated stone for many purposes because stone was more appropriate. Look at the macuahuitl- the spaniards weren't kidding when they said you could behead a horse without slowing down with one, obsidian blades are just impossibly sharp if made with skill. What incentive is there to drop that lightweight yet immaculately-sharp sword in favour of something that's far heavier, duller, more expensive and more logistically-challenging to manufacture in large quantities? A 1500s Spanish steel sword could probably "outperform" a macuahuitl by many metrics, sure. All the intermediate steps to get to that lightweight tempered carbon-steel sword- the shittier steel swords and the wrought iron swords and the bronze swords- were likely inferior. No impetus to change what ain't broke. Ambrose Burnside fucked around with this message at 05:20 on Aug 5, 2017 |
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Aug 5, 2017 04:49
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That is a really fascinating set of effortposts, thanks!
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Aug 5, 2017 04:49
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Have any of you machined bronze before? I've done brass. It's weird. It squeals horribly and then you look at it and the finish is beautiful.
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Aug 5, 2017 09:09
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Volkerball posted:Have any of you machined bronze before? I've done brass. It's weird. It squeals horribly and then you look at it and the finish is beautiful. Bronze Edms like steel, brass cuts fast as hell though.
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Aug 5, 2017 12:26
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Volkerball posted:Have any of you machined bronze before? I've done brass. It's weird. It squeals horribly and then you look at it and the finish is beautiful. I've cut enough bronze steady rests to choke a Mesopotamian goat. We use a specialty bronze for our rests. A really sharp, really stout, lightly oiled, carbide cutter works pretty well.
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Aug 5, 2017 13:52
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Someone told me that if you want to do much regular turning work on cuprous alloys you should get yourself some negative-take tools to use, something to do with chatter. Haven't tested it myself, though. I've actually got a length of 3/4" architectural bronze bar i've been saving for something decorative, if I get around to that i'll post about it.
Ambrose Burnside fucked around with this message at 21:41 on Aug 5, 2017 |
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Aug 5, 2017 21:39
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On the subject of ferrous alloys: Is there a happy medium between "dirt cheap" and "can be case hardened" that I could ask a metal supplier for? I'm leaning more towards cheap, but I don't want to be "that guy" who walks into a shop and asks for "mild steel" like it's an official designation. edit: Is it A36? Or is it fancy and weird like A2? DreadLlama fucked around with this message at 08:03 on Aug 6, 2017 |
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Aug 6, 2017 08:01
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DreadLlama posted:On the subject of ferrous alloys: Is there a happy medium between "dirt cheap" and "can be case hardened" that I could ask a metal supplier for? I'm leaning more towards cheap, but I don't want to be "that guy" who walks into a shop and asks for "mild steel" like it's an official designation. I'm pretty sure A36 is what you're thinking of. Its the most common structural steel.
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Aug 6, 2017 08:05
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DreadLlama posted:On the subject of ferrous alloys: Is there a happy medium between "dirt cheap" and "can be case hardened" that I could ask a metal supplier for? I'm leaning more towards cheap, but I don't want to be "that guy" who walks into a shop and asks for "mild steel" like it's an official designation. A36 or 1018 yea, that's probably what you're looking for. Wouldn't say A2 is weird and fancy though, just maybe higher quality than you're looking for, it can be heat treated. We probably cut that more than anything else at work. A Proper Uppercut fucked around with this message at 11:51 on Aug 6, 2017 |
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Aug 6, 2017 11:47
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Any steel can be case-hardened, so far as I know, but the technique most benefits steels that don't have enough carbon in them to be hardenable as-is; the apparent benefits would probably be quite limited in a steel that's already got a fair bit of carbon in it (and it's possible you could partially-decarburize already-higher-carbon steels if you didn't use good quality control while case-hardening). In other words, yeah, A36/whatever your local designation for the absolute cheapest hot-rolled stock they have will do just fine. I don't remember, why are you intent on case-hardening this metal? If it's just to learn/for the experience, go for it, but case-hardening for a fairly crude tool makes a lot less sense with modern alloys than it did when making the tool out of soft iron and case-hardening it was often more economical than making the whole thing out of carbon steel. Traditional case-hardening needs a lot of prep and a prolonged soak at high temps (we're talking hours and hours, overnight is common) that will consume a shitton of fuel. If you're using a modern case-hardening process, fine, but the return is still... questionable, again unless this is just for fun. I have a can of Kasenit I've occasionally used for fast case-hardening, but I really haven't had many reasons to use it. If I'm making a hard-wearing tool I just start with the right alloy and temper it as usual. When I -have- used it productively, it was in situations where I didn't have that luxury and had to roll with the stock on hand- for example, I did a run of small knives made out of screws and nails years ago, and I case-hardened them after forging and grinding was done because the wire stock used for most nails and screws is especially low-carbon and soft. It put a thin hardfacing on 'em that let me get a few resharpening/honing cycles done before I hit the soft core that wouldn't hold an edge. If high-carbon nails were a thing on hand I would have used them without hesitating.
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Aug 6, 2017 18:06
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I've turned a fair bit of bronze with carbide tools. It shoots out swarf like sand and goes everywhere. Horribly messy. Gets down my shirt and in my hair.
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Aug 6, 2017 22:44
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Double post: Buying a second Sherline mill tomorrow....do I need 2 small mills? Nope. Now I will have one Sherline lathe and mill at work, and a sherline lathe and mill in my new 'workshop' room in my condo. I'll also have to build a nice enclosure so I don't get the room too full of chips.
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Aug 7, 2017 01:41
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Ambrose Burnside posted:Any steel can be case-hardened, so far as I know, but the technique most benefits steels that don't have enough carbon in them to be hardenable as-is; the apparent benefits would probably be quite limited in a steel that's already got a fair bit of carbon in it (and it's possible you could partially-decarburize already-higher-carbon steels if you didn't use good quality control while case-hardening). In other words, yeah, A36/whatever your local designation for the absolute cheapest hot-rolled stock they have will do just fine. Couple reasons: #1 I need to build an evaporator arch:  I think it's supposed to be made of mild steel because otherwise it'd get brittle, which I think could be scary if it's got a few dozen litres of boiling maple sap sitting on top of it. Also it would be nice to use the cheapest steel possible for economic reasons. Second, if I've got some extra laying around at the end of the project, it would be nice to try case hardening a shovel blade and/or chisel for fun. I mean, an evaporator is something that typically runs for weeks at a time. It would be something to do for fun to stop from going crazy when I'm 3 weeks into a 6-week boil. Also, it would be nice to have an upgraded heavy shovel with a hard edged blade by the end of next April. Every tree I plant now is another tree I (or someone else) gets to tap later.
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Aug 7, 2017 06:13
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None of that addresses why you want to case-harden the steel, though. I thought this was for the shovel, I didn't realize you wanted to do much larger pieces of steel. I'd abandon the case-hardening idea entirely, to be frank. None of this makes any sense to me. You'll be taking a material with known and predictable engineering properties and putting a great deal of energy and effort into turning it into a material with totally-unknown engineering properties, and probably in an inconsistent way to boot. You've never done this before, so far as I know, and you want to start with very large pieces of metal, which will require a very large fire to be sustained for many hours. You want- low cost? Case-hardening will add significantly to costs with negligible (or possibly even negative) gains elsewhere. You want- durability and no brittleness? Case-hardening may do the opposite of that. Case-hardened layers can have enough carbon to become accidentally-hardenable, and thin metal can case-harden all the way through. To reiterate, case-hardening on an amateur scale only makes sense in very specific and limited circumstances, and this definitely isn't one of them. All I see for you if you tackle this is a lot of wasted effort and money when plain stock would have done the job just fine.
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Aug 7, 2017 18:24
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Ok. I won't try to case harden a shovel blade by sticking it in maple sap arch. A36 is still good for heating up for a long time without becoming brittle though, right?
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Aug 7, 2017 18:55
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DreadLlama posted:Ok. I won't try to case harden a shovel blade by sticking it in maple sap arch. I don't think a syrup evaporator has anywhere near enough temp to make it brittle? Maybe if you were blasting the steel with the heat source directly?
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Aug 7, 2017 19:22
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It's being heated by a flame and isn't heated without sap in it, right? Yeah, accidentally hardening the metal was never a serious risk, you'd need to get it glowing hot for that to be remotely-possible, and I suspect if that happens something will have gone very wrong with the process. I suspect the real issue you'll run into over the long term will be 1) rust and 2) the evaporator portions exposed to flame thinning and eventually developing holes. Heat-resistant rust protection addresses the first, and thicker sheet stock addresses the second.
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Aug 7, 2017 19:29
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I've made two maple syrup evaporators. One out of a fuel oil tank with stainless steel cambro containers that drop in, and the other out of the cheapest steel known to man. (What someone brought in) The fuel oil tank worked really well. I just torched the top open to fit the stainless steel evaporators and then the dude added sand to the inside to get the proper flow. Who am I kidding, they are mostly shitfaced drunk the entire time. It's amazing that any syrup comes out at all. The square tubing frame is still holding up well. Corrosion is going to be the biggest issue, wood ash, heat, and oxidization are going to wreck it. But the sap part is going to hold out fine. (stainless steel cambros again) We're just going to roll with it and see how it dies. In hindsight I'd have scrounged up some stainless 16 gauge and used that in the high heat areas. Or firebrick would work too.
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Aug 8, 2017 02:47
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Design question, I want my sheet metal brake to be able to do boxes, in it's current form it can't do them and it also can't do sharp corners, there's always a pretty significant radius, which is fine sometimes, but sometimes I want really crisp and sharp corners, like when I am trying I've looked at some commercial models and came up with a new design, mostly using 8mm thick mild steel parts since that's what I got. Pretty rough so far, just to help me get an idea of what it could look like. Does it look sturdy enough? There are two 620x35x8mm bars that hold the "bending plates" (no idea what you call them) in place, not sure if this would be rigid enough. The idea is you move the plates in position and lock them down with bolts.  Edit: Gotta say I found this image soon after posting and it looks like it has some design improvements so I could use less material, the linkage is cool but perhaps too complex for me. https://s-media-cache-ak0.pinimg.com/originals/bf/a1/27/bfa127a1c9bd2befe09c81454b223069.jpg His Divine Shadow fucked around with this message at 19:46 on Aug 9, 2017 |
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Aug 9, 2017 19:32
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I can't speak to your press brake design, but irt sharpness, I've used scoring to get very, very crisp bends (corner radii too fine to see-sharp). You can score with a triangular graver, a dremel cutoff wheel, or (my fave technique) hard wire. The first two remove some metal that the bend closes- weak bends that should be soldered for strength- while wire-scoring involves hammering wire into the sheet metal to create a work-hardened groove that's reasonably strong post-bend all on its own. Wire scoring also lets you do radiused bends, so you can create some really geometrically-complex forms with little work or preloading, it's fun to fart around with. e: note that score-folding is only commonly used for small, cosmetic-first boxes and stuff like that, i suppose you're probably folding big stuff Ambrose Burnside fucked around with this message at 21:36 on Aug 9, 2017 |
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Aug 9, 2017 20:40
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Maybe I missed it in your post, but what thickness of material are you planning to bend up with this? And what do you consider to be an acceptably sharp radius?
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Aug 9, 2017 20:44
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I uhh, don't know if this is the right thread, but I'm trying to apply some steel to a piece of flint to make a necklace and the internet has proven extremely unhelpful. I kinda thought there would be diy jewelry thread in the subforum but uhhh, I suppose this is the closest thing? I'm still just in the planning stages, but any help whatsoever would be appreciated.
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Aug 9, 2017 21:59
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If you mean a nondescript piece of flint and a nondescript lump of steel, a decent epoxy will probably be your best bet. Rough up both objects on the surfaces to be joined and make sure they're otherwise clean and dry. If these objects have a shape conducive to it, wiring them together with brass/copper wire will be fast and easy and secure if nothing can slip off.
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Aug 9, 2017 22:17
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Rotten Cookies posted:Maybe I missed it in your post, but what thickness of material are you planning to bend up with this? And what do you consider to be an acceptably sharp radius? Around .8mm and .7mm sheet metal, can't put in figures how sharp a radius I want, only as small as I can get it.
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Aug 10, 2017 04:07
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Steel, i'm assuming? If you're not doing precise assemblies, one workaround you can use post-bend is hammering the bends on an appropriate anvil or dolly (a block of steel that will fit inside your sheet metal forms with a very slight radius on the edges so they aren't sharp will work). Snug the edge of the bend up to the anvil edge and hammer the sheet top where the bend radius starts with a good, gently-crowned hammer- this will flatten part of the radius, effectively sharpening the corner by forcing the reduced bend to take up the necessary angle. Flip the part to crisp up the other side of the radius to even the bend out. If you're losing your angle, carefully re-bend it a little if the part allows (finished boxes tend to resist this because the other folds reinforce the one you're working, but there may be some visible bowing at the middle you can fix over the anvil or with careful finger/plier-bending. DO NOT hammer the bend directly onto the edge, this will deform or shear the sheet. Practice with some scrap sheet, it's pretty easy to pick the general principle up. It's fast and easy for small, uncomplicated forms with loose tolerances, I've used it for a range of modest boxes (~15 cm square or less) and random sheet metal projects. Ambrose Burnside fucked around with this message at 00:05 on Aug 11, 2017 |
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Aug 10, 2017 23:58
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His Divine Shadow posted:Around .8mm and .7mm sheet metal, can't put in figures how sharp a radius I want, only as small as I can get it. I cant find it quickly but I think MMPDS has minimum bend radii for certain alloys if youre trying to design something versus just making a prototype
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Aug 10, 2017 23:59
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plan on 1 - 1.5x thickness as the best inside radius you're going to get
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Aug 11, 2017 00:08
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CarForumPoster posted:I cant find it quickly but I think MMPDS has minimum bend radii for certain alloys if youre trying to design something versus just making a prototype yeah this is the other thing, there are ways to put very crisp edges on sheet metal bends but if the application isn't mostly aesthetic it isn't a good idea because you'll be compromising its strength past a certain point. i can put a functionally-perfect square edge on some copper-brass sheet, with a crisp corner and everything, but that bend ends up much weaker than a typical bend so I don't unless it's foldformed art or sth that just sits on a shelf being pretty.
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Aug 11, 2017 00:11
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Ambrose Burnside posted:yeah this is the other thing, there are ways to put very crisp edges on sheet metal bends but if the application isn't mostly aesthetic it isn't a good idea because you'll be compromising its strength past a certain point. i can put a functionally-perfect square edge on some copper-brass sheet, with a crisp corner and everything, but that bend ends up much weaker than a typical bend so I don't unless it's foldformed art or sth that just sits on a shelf being pretty. shame on an IGA posted:plan on 1 - 1.5x thickness as the best inside radius you're going to get There are definitely alloys (7075-T6) and thicknesses for which this is going to cause microcracks. I dont know where this chart came from but here's a chart: http://www.americanmachinetools.com/bend_radius.htm 7075-T6 wants a 5X thickness on the lower end. Most not-aerospace-people will be bending 2XXX-T2/3, 5XXX-Hwhatever or 6XXX-T4 or T6. in which cause 1.5x is a decent min. Also if youre bending 7075-T6 and you live in a humid or salty environment you will get stress corrosion cracking.
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Aug 11, 2017 00:42
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You know... this is interesting. Help me stop myself. http://aaybee.com.au/Magnabend/Building%20Your%20Own%20Magnabend.html
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Aug 12, 2017 07:30
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Are the hinges on it weird like that to account for different thicknesses of metal or the longer stroke? I'm missing why they went with such a weird design. Also don't do it because it's expensive? I'd use more copper, and rather than use thermoset use varnish then vacuum cure it.
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Aug 12, 2017 12:29
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DreadLlama posted:Couple reasons: "A few dozen litres" of mostly-water weighs about a hundred pounds. If you're designing a steel frame like that and worrying about whether it can stand up to a hundred pounds of load, hardened steel or not, you've done something extremely wrong.
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Aug 13, 2017 14:23
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The sap / syrup will be somewhat denser than water because of the sugar content but even in the worst case of pure cold syrup it shouldn't be over 1.5kg/L
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Aug 13, 2017 16:20
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Sagebrush posted:"A few dozen litres" of mostly-water weighs about a hundred pounds. If you're designing a steel frame like that and worrying about whether it can stand up to a hundred pounds of load, hardened steel or not, you've done something extremely wrong. Most people's experiences are with aluminum in their IKEA furniture, and don't really have a concept of how strong steel is in comparison. Unless you've taken some materials science classes most people just don't have the experience to estimate high weights and stresses outside the human scale
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Aug 13, 2017 16:31
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M_Gargantua posted:Are the hinges on it weird like that to account for different thicknesses of metal or the longer stroke? I'm missing why they went with such a weird design. They use that design so they can have a completely open design, with this hinge they can hang stuff over the side and only bend a portion of the part being worked on, with a normal hinge you could not do that. Been looking at this all weekend and I really wanna do it now...
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Aug 14, 2017 06:35
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His Divine Shadow posted:They use that design so they can have a completely open design, with this hinge they can hang stuff over the side and only bend a portion of the part being worked on, with a normal hinge you could not do that. But the hinge is under the bending lever!? Hanging stuff over the side is just a feature of the magneticly couples piece.
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Aug 14, 2017 06:47
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The reason that the hinge can be placed under the lever, so that the sides remain open, is because of it's particular design. You couldn't do that with a regular hinge, it would get in the way, magnetic coupling or not.
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Aug 14, 2017 07:39
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One of the Mazaks threw a tombstone last night. Just file it up, she'll be fine.
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Aug 15, 2017 14:22
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Do any of you have an opinion of the MIFCO F-512 forges? I got this one years back for like $50, and it was set up to run on propane.  I assume the firebrick probably should be replaced, and the electrical systems and valves should be checked out. I also plan on building a dedicated wheeled base for it as I actually need to free up that cart. The guy I got it from used it for making decorative iron things, but I'm not sure what I would use it for yet.
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Aug 18, 2017 20:02
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I'm in Boston this weekend. Went to harbor freight for the first time in my life. We don't have them in Canada. Can't say I didn't enjoy the cheap poo poo they sell.
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Aug 19, 2017 03:25
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