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Ambassadorofsodomy posted:Is there any reason to heat up parts with a torch before welding them? It depends. If you are welding structural mild steel then it is generally not needed. Alloy steel generally requires some form of pre/post heat. Cast steel parts can use preheat to minimize cracking though this is less critical than for cast iron.
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Jul 15, 2022 17:07
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Long shot here... anyone know of a waterjet or (preferably) a laser shop that cuts structural materials? I'm talking Angle and Channel. I can only find places that cut flat sheet/plate. Is it unreasonable due to the tech? I didn't think so, but I can't find anyone that does it which makes me wonder.
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Jul 19, 2022 17:16
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sharkytm posted:Long shot here... anyone know of a waterjet or (preferably) a laser shop that cuts structural materials? I'm talking Angle and Channel. I can only find places that cut flat sheet/plate. Is it unreasonable due to the tech? I didn't think so, but I can't find anyone that does it which makes me wonder. Laser is going to be an issue due to the different heights. You would probably have better luck with waterjet. You could try south shore manufacturing in Hanson, MA(my old shop I left a couple years ago), they have 3 Waterjets and a fiber laser cutter. Also S&T Precision in Whitman, MA has a few WJ machines.
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Jul 19, 2022 17:55
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One of the teams after I graduated had the tubes laser notched for our Formula SAE chassis. I think it was this company https://www.rimetal.com/laserquote:-Up to 12” o.d. round, 9” sqr. & rect.
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Jul 19, 2022 18:51
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A Proper Uppercut posted:Laser is going to be an issue due to the different heights. You would probably have better luck with waterjet. You could try south shore manufacturing in Hanson, MA(my old shop I left a couple years ago), they have 3 Waterjets and a fiber laser cutter. Also S&T Precision in Whitman, MA has a few WJ machines. bred posted:One of the teams after I graduated had the tubes laser notched for our Formula SAE chassis. I think it was this company https://www.rimetal.com/laser Thanks!
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Jul 20, 2022 13:30
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I need to fab this thing: My notion is to cut it out as a T and then fold the wings down. Unsure if it's better in aluminum or steel, both are fine as a material for this, but I'm not sure how thick of a material I could reasonably make such a bend in (or, probably more accurately, have someone with the right tool make such a bend). The tolerance between the wings once they're folded down is somewhat tight, as it needs to fit over some aluminum extrusion. Am I better off cutting it as three pieces and welding the wings on at a right angle, or is the fold approach at all reasonable? The above render is 1/4", I think in aluminum I'd want it to be at least 3/16, I'm not sure what a similar rigidity in steel would require. I am happy making construction more complicated in order to stay as close to zero wiggle in this thing as possible. Probably over-doing it all around but I'm okay with that too. Bad Munki fucked around with this message at 23:31 on Jul 23, 2022 |
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Jul 23, 2022 23:28
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Bad Munki posted:I need to fab this thing: That there is a perfect 90 degree notch so its only possible to make that by welding on tabs or machining it. That said there are plenty of brackets folder over in this way to make basically any stamped hitch or clevis. For example this 3/16 steel clevis is folded similarly but not the radii:  You can find a chat of minimum bend radii vs material and sheet thickness by googling. If I was making QTY 1-10 of those things and tolerances werent tight I'd definitely plasma/laser/water then bend it, possibly with a torch and hammer. EDIT: Somewhat tight isn't a tolerance. If you're using a straight out of the die extruded bit of aluminum thats 1/4" thick the tolerances of the extrusion (likely greater than +/- 0.010") aren't somewhat tight by the definition of basically any machinist, but might be by the definition of a welder or woodworker. CarForumPoster fucked around with this message at 23:48 on Jul 23, 2022 |
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Jul 23, 2022 23:44
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I think welding will be your best bet if you need that sharp inside corner.
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Jul 23, 2022 23:52
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I’d probably bend it then hit the inside corner with a file. What sort of aluminum extrusion?
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Jul 23, 2022 23:59
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Depends a lot on what tools you have access to or if you're going to farm it out. I'd cut and weld but I have the tools to do that easily at that thickness.
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Jul 24, 2022 00:05
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bend it, know what the inside radius is gonna be and then chamfer the extrusion appropriately.
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Jul 24, 2022 00:09
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The Bandit posted:I’d probably bend it then hit the inside corner with a file. What sort of aluminum extrusion?  CarForumPoster posted:EDIT: Somewhat tight isn't a tolerance. shame on an IGA posted:bend it, know what the inside radius is gonna be and then chamfer the extrusion appropriately. honda whisperer posted:Depends a lot on what tools you have access to or if you're going to farm it out. quote:If I was making QTY 1-10 of those things and tolerances werent tight I'd definitely plasma/laser/water then bend it, possibly with a torch and hammer. Thanks for all the responses! Bad Munki fucked around with this message at 00:24 on Jul 24, 2022 |
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Jul 24, 2022 00:19
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Bad Munki posted:I have the tools to cut and weld, Perfect! Thats a 90 minute part. (So it'd take me all day) Lay it out, cut it and weld it up, then drill your holes once its right
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Jul 24, 2022 00:50
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You can bend that with a box and pan brake, most of the way anyway. Plenty far enough to set the crease and push it the rest of the way with a hammer or something.
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Jul 24, 2022 01:52
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You can put a small chamfer on the end of the 8020 to clearance any internal radius on the bend. It's be cheaper to do bent imo if you're jobbing it out, might be cheaper to weld it yourself if your time doesn't have an associated cost.
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Jul 24, 2022 02:23
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the precision of width is not gonna matter for that application with the threaded fasteners you've got specced for it. Tighten from bottom to top and it's not gonna have any wiggle, if it's really loose at the top of the side legs just shim it as needed. You're bigly overthinking this. E: where's the guy that just bought half a ton of shim stock you got a customer shame on an IGA fucked around with this message at 02:36 on Jul 24, 2022 |
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Jul 24, 2022 02:31
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Nah, not content with shims, half the point of this over engineered toy is the aesthetics and the joy of getting it perfect. I'm okay with that aspect making my life difficult. e: The other half is the extremely over-built nature of the design. Bad Munki fucked around with this message at 03:24 on Jul 24, 2022 |
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Jul 24, 2022 03:20
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If you have the tools to cut and weld I'd go that route for a quantity of 4 provided there it isnt a huge opportunity cost for your time.
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Jul 24, 2022 03:28
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shame on an IGA posted:the precision of width is not gonna matter for that application with the threaded fasteners you've got specced for it. Tighten from bottom to top and it's not gonna have any wiggle, if it's really loose at the top of the side legs just shim it as needed. You're bigly overthinking this. If the pieces are a hair oversize and wiggly, couldn't you just tap them with a hammer to close the wings a bit? Not even enough to see, just a nudge
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Jul 24, 2022 05:11
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https://twitter.com/GenerMo/status/1551123902360961024?s=20&t=yXPP4XoziDu9sSOdc17g9A Cross-post from ukraine threads. How do you think this happened?
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Jul 25, 2022 06:14
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HolHorsejob posted:https://twitter.com/GenerMo/status/1551123902360961024?s=20&t=yXPP4XoziDu9sSOdc17g9A Rifled barrels still start life out as stamped slugs that are drawn as twisted as far as I know. And that looks round in the picture - hard to tell with a photo. So I'd say you draw a barrel out and chuck it up wrong/out of center in the lathe and just keep rolling with it rather than measuring or correcting as you turn it down.
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Jul 25, 2022 13:18
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HolHorsejob posted:
If that is from a BMP-2, it's a 30mm barrel with a length of ~ 2.4 meters. The picture looks to be a section, so it could be centered at the beginning, wander in the middle, and straighten out in the end. Or whacky like a corkscrew banana the whole way through. I'm not familiar enough with gundrilling machinery to guess, but having designed reamers for 4-6 inch deep holes I absolutely know this can happen with dull tools, insufficiently robust cutters, and poor setups. It's probably a combination of all three. edit : Unisig production cell showing the process flow. https://unisig.com/wp-content/uploads/2022/01/U1002_UNISIG_Firearms_Industry_Solutions-Brochure-EN-US.pdf Yooper fucked around with this message at 13:30 on Jul 25, 2022 |
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Jul 25, 2022 13:20
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It could be that the thicker part is supposed to be at the bottom to counteract the barrel sagging or something? Or just lovely Russian/soviet quality control.
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Jul 25, 2022 14:38
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Someone should page Ensign Expendable for a closer look, but I think it's intentional. https://thesovietarmourblog.blogspot.com/2016/05/bmp-2.html Scroll down to the 2A42 section for more info. They don't reference the difference in thickness, but there is the gas blowback assembly and it appears that the wall thickness is thinner at that point.
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Jul 25, 2022 14:57
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Motronic posted:Rifled barrels still start life out as stamped slugs that are drawn as twisted as far as I know. And that looks round in the picture - hard to tell with a photo. So I'd say you draw a barrel out and chuck it up wrong/out of center in the lathe and just keep rolling with it rather than measuring or correcting as you turn it down. I dont think anyone would draw an 8mm thick steel part. I'd be amazed to see a stamped part as well, not very likely. Barrels are most likely forgings (in larger diameters) or bar stock. Re: how to do it Most of the 4 jaw chucks you see in machine shops are not self centering. So you can drill a hole thats on center with the headstock's bore but not concentric to the part's chucked up portion by moving the part off center. Thats how they could machine crankshaft rod journals on a lathe for example. I'm with Yooper's suggestion that this is intentional and there may be additional stuff going on such as a gas blowback system further up the barrel.
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Jul 25, 2022 22:59
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I'm still working on getting that new handle on my axe that I posted about a while back. I've been leaving the head soaking in Vinegar for a while now, and most of the rust and old paint has been stripped off of it. Aside from a bit of stubborn rust in the eye, which hopefully will be gone in a day or two. I just changed the vinegar again yesterday, and going to do it again today too. Just wondering, once I do get this thing done, what should I do to keep this thing from rusting again? I don't really want to paint it though I *might* do it. But I'd kinda like to keep the metal bare. I was thinking of using Remington CLP, its some gun cleaning poo poo that is alleged to "Clean, Lubricate and Protect". I figured I'd spray the entire head except for the edges. Or maybe I should spray the edges too? Is that stuff poo poo? It sees to work reasonably well on guns IME.
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Jul 27, 2022 12:46
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Ambassadorofsodomy posted:I'm still working on getting that new handle on my axe that I posted about a while back. I've been leaving the head soaking in Vinegar for a while now, and most of the rust and old paint has been stripped off of it. Aside from a bit of stubborn rust in the eye, which hopefully will be gone in a day or two. I just changed the vinegar again yesterday, and going to do it again today too. Your options for preventing steel rust are basically passivating the steel (e.g. bluing, intentional rust "patina") , applying a bonded protective layer (e.g. paint, electroplating), or regularly applying a liquid protective coating (e.g. WD40). Black coated drill bits and dark gun barrels are "blued". If you have ever left a black barreled gun or black oxide drill bits out in the rain or a humid garage, you've likely seen them start to develop corrosion. Bluing isnt exactly great for stopping corrosion long term in harsh conditions nor is it very abrasion resistant. That said IMO it looks nice. Bluing + paint is a pretty good solution. You can use vinegar or other chemicals to passivate the steel forming a "patina" appearance which can be from dull grey to red rust. The "farm and implement" and "rust stop" paints usually have agents in them to promote adhesion and passivate steels. If you go the paint route, these are usually superior anti corrosion options. Spray on gun lubricants are fine too. WD40 should be fine, though it tends to need fairly frequent reapplication. Pretty much any combo of the above works well together too. Passivation + oil will be better than just passivation or oil.
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Jul 27, 2022 13:06
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Ambassadorofsodomy posted:Just wondering, once I do get this thing done, what should I do to keep this thing from rusting again? I don't really want to paint it though I *might* do it. But I'd kinda like to keep the metal bare. I was thinking of using Remington CLP, its some gun cleaning poo poo that is alleged to "Clean, Lubricate and Protect". I figured I'd spray the entire head except for the edges. Or maybe I should spray the edges too? Is that stuff poo poo? It sees to work reasonably well on guns IME. CLP, or any light oil would work fine. The bigger issue will be how and where it's stored. Leave it in a shed against a cinder block wall and you'll have rust regardless of what you put on it. Hung on a wall or in a tool cabinet in a not ridiculous humidity and you'll be fine. I've seen axe wax and such but have not tried it myself. A woobie around the head is also sure proof rust prevention.
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Jul 27, 2022 13:14
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Let it get a thin coat of brown rust, then coat in fluid film, paste wax, or a mix of beeswax and boiled linseed oil, thinned with turpentine, if you feel fancy. Keep the rag where you store the axe, and give it swipe when you put it away.
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Jul 27, 2022 13:25
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An axe head has a ton of metal. Protect the edge of the blade, and some surface rust on the rest of it is basically harmless. All of the above advice is fine and well of course, but I think the key thing is to not worry about it. A couple decades in your shed won't matter, especially if you pick it up and use it once a year and give it a bit of a rub with some some kind of oil when you do.
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Jul 27, 2022 23:54
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I painted my axes, because that was the factory look: The untreated parts got some light oil. Also been fabricating replacement parts for my car, 4 of these now. I think it's called a sill plate. The lower portion of the part that's under the door, towards the road: 
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Jul 28, 2022 06:55
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hi metal heads i got a piece of outdoor equipment made out of painted sheet metal (it's a wheelbarrow). the a307 bolts are rusting. would it be a bad idea to replace them with stainless steel fasteners? or do i risk galvanic corrosion by doing this?
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Aug 16, 2022 18:34
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DELETE CASCADE posted:hi metal heads There may be some galvanic corrosion but it'll be very minimal compared to the sort of wear and tear a well used wheelbarrow sees. So unless you're a sprightly young person with intent to lovingly maintain this wheelbarrow for the next 60 years, go for it.
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Aug 17, 2022 14:10
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You could also put some anti-sieze on them to be the sacrificial corroded bit.
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Aug 17, 2022 14:46
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armorer posted:You could also put some anti-sieze on them to be the sacrificial corroded bit. Anti seize everything. If you don't have hands like the tin man by the end of the day, you need more anti-sieze. I've been working on stuff in our facility long enough that I've run into things from when I first started so the only person I can curse for not using it is myself. Then I tear apart something from 2012 Yooper and am like "yes, this man used anti-seize". Anyone going to IMTS?
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Aug 17, 2022 15:45
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DELETE CASCADE posted:hi metal heads Very much a lurker/not that knowledgeable, but nylon washers to reduce contact of the two different metals at the surface might help too.
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Aug 17, 2022 21:39
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A friend of mine just had someone cut the catalytic converter off her truck. Is there a good way to defend against an angle grinder? Like, is there a metal that's guaranteed to gum up and shatter the wheel?
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Aug 18, 2022 01:56
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HolHorsejob posted:A friend of mine just had someone cut the catalytic converter off her truck. Is there a good way to defend against an angle grinder? Like, is there a metal that's guaranteed to gum up and shatter the wheel? There are cable kits you can install, they won't prevent it 100%, but just make it much more difficult. One I've seen is just a bunch of cable loops while another is encapsulated cables so the sawzall can't get a cutting grip. If someone is 100% determined then you're kind of hosed, but this should be a solid deterrent. Another option could be a skid plate with tamper proof fasteners.
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Aug 18, 2022 02:07
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HolHorsejob posted:A friend of mine just had someone cut the catalytic converter off her truck. Is there a good way to defend against an angle grinder? Like, is there a metal that's guaranteed to gum up and shatter the wheel? Non ferrous metals can clog grinding tools but after my cat got stolen last october I found that the general suggestion is to add steel in strategic places so it takes significantly longer to cut out the cat.
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Aug 19, 2022 00:10
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Ziggy Smalls posted:Non ferrous metals can clog grinding tools but after my cat got stolen last october I found that the general suggestion is to add steel in strategic places so it takes significantly longer to cut out the cat. If you forget what cat is short for, which I totally didn't do, this becomes a very different message.
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Aug 19, 2022 01:20
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