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RealKyleH posted:Anyone know where I can find some info about welding dissimilar thicknesses of aluminum with AC tig? I want to weld a 1/8" walled velocity stack to a large 1/2" base plate but I cant get a puddle going on the base plate and the end of stack at the same time to even tack them together. I do GTAW welding almost exclusively, and doing dissimilar thicknesses is all about proper torch angle and heat application. It's a weird bastard compound angle on the torch in order to get it to melt out right and have it controllable and not full of oxidation. Tip the torch back along thw axis of the weld about 15-20 degrees from vertical, and tip the torch more toward the larger base plate than the thin wall. Experiment slowly changing the angle of the torch and the heat until you can get both parts to puddle at about the same rate. One of the tricks is to take the tungsten, loosen it up, and touch both the ceramic cup and the tungsten to the plates. The cup touches the walls and the tungsten touches the part where they join. This gives you the right length in order to get into the corner without getting an overly long arc or losing gas coverage.
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Aug 1, 2008 05:35
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pocketpencil posted:Depends on the machine ( got 2 different types) I can see how you could articulate the rotary device along all 3 axis, but you can get equivalent motion using just the tilt and rotation, while simplifying the setup and increasing rigidity and repeatability. Nowadays, at least according to HAAS, they combine the rotary chuck and table into one item, since for most fixturing, a trunnion table 4/5th axis combined device is able to machine 5 sides of a part and depending on tooling and clearance, some of the underside. I suppose you could also articulate the mill head in addition to the trunnion table, but that's such a weird bastard setup that most CNC software systems aren't even able to adequately program for it. I can see how on something really bizarre like those new GE turbofan blade assemblies would you need to be able to rotate the part through that many axis in order to profile the backs of the blades properly. And given the retardedly low machinability of almost all superalloys like waspalloy or haspalloy, 36 hours of machine time seems about right for that much material removal. God that block must have cost a loving fortune. Nerobro posted:I've got the plans and the materials to build: http://www.crankorgan.com/brute.htm My original intent was to run it as a manual mill. Maybe I'll do that next week. Oh god, please don't build anything using aluminum as a structural component if you're doing more than doing CNC etching and milling of PCBs and other really light duty stuff like that. Good rule of thumb is if you can flex a 6 foot section of it enough to notice, it's a lovely material to use as the basis of your milling machine. While those extruded aluminum channel rods are great for a quick and dirty setup, they'll be about as accurate as an echa-sketch and a patient 5 year old. I might be a bit of a fanatic about this, but I play with CNC machines for fun at school, and there is really a hugely complex and detailed science and techniques behind building a proper tool. Just for shits and giggles, I'll walk through how I'd build my own mini-mill. 1) Use grey cast iron for pretty much everything structural. The table, base, guides and ways (the parts the rub together when the table moves on an axis), and head assembly would all be made out of grey cast iron blocks. 2) Machine all the parts in a CNC mill, or if one is unavailable a manual mill with a backlash eliminator and a digital readout. 3) Use a surface grinder and a set of master's tool squares to make sure that everything is flat, square, parallel and true. 4) Use a big loving surface plate and dial height gauge to make sure that everything is all flat and kosher. 5) Buy pre-ground ball bearing drive screws and nuts, way easier to spend the cash and get top notch quality than try and halfass it myself and end up with a table that moves non-uniformly. 6) Use dowel pins for the drive screws and nuts to insure that the table is driven in a way that's perfectly parallel with the ways, otherwise it'll bind and do odd poo poo. This is just off the top of my head, but the major things to look for is squareness (if you don't have a granite surface plate or know a place you can use theirs at, don't expect your mill to cut poo poo on a straight line or anything close to 90 degrees. Next is rigidity, if you can bend it, those motors you're using to move the table around probably can too, and will if you gently caress it up or press too hard. Attention to detail is critical, a tiny fuckup, like a few thousandths of an inch (impossible to see outside of certain circumstances, like holding a steel rule up to a block and looking for light) can cause consistent or even non-reproducible errors in anything you try to do later. This means that little circuit you tried to make will end up having either bad traces, or holes that won't line up with the ICs. Methylethylaldehyde fucked around with this message at 13:10 on Dec 15, 2008 |
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Dec 15, 2008 12:54
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Nerobro posted:Since I bought all the parts before I knew better, there's no reason not to try. There's no reason to expect better than .005 from it, as that's the runout on a dremmel anyway. ;-) If it's just for fun type thing, yeah, I can see how real accuracy wouldn't be too much of an issue. One trick for the threaded rod is to buy a die set that includes that thread type, and use it to insure the threads are at least formed properly. The threaded rod you get at home despot and poo poo is rolled, and it can be a bit of a bastard to use sometimes thanks to non-uniform thread height, depth and spacing. Chase the threads out with your $20 in tooling and the rod will work a lot better. Same with the nuts, better to be sure the mass produced stuff you bought is exactly to spec, plus the tools never really go bad, and you need to start your collection of stuff eventually. Apparently this little mill includes pretty much every trick I know to get more accuracy out of the system without needing really special tools to do so. This is good. Aside from the obvious lack of rigidity or ability to use it like I use a normal CNC mill, it's a pretty neat little project to get set up in a week or two.
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Dec 15, 2008 20:43
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Nerobro posted:My threaded rod didn't come from mcmaster. Not that I really trust it. I'll definitely take a die to it, I hadn't thought of the thread form being screwy. Given I buy good taps.. that could be a bit of a bind. They're shipped bulk, and they're made on a worn out machine in china someplace that cranks them out by the metric asston. They're probably banged around enough during shipping that they've got oblong sections of thread or mashed over thread crests. I've had threaded rods that wouldn't go over the really lose nuts you buy from home depot, even after chasing out the threads with a good tap. The rod I bought was so bad that I ended up having to use a nut to physically straighten the threads before the die would do more than chew the entire rod up. And I was using the rod to make a hanging shelf for the underside of my desk, not a precision tool. Methylethylaldehyde fucked around with this message at 21:43 on Dec 15, 2008 |
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Dec 15, 2008 21:40
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oxbrain posted:Unless you're doing a ton of machining it isn't worth spending too much time worrying about insert selection. TiN or TiAIN is a good all purpose coating. Great for carbon steels, pretty good with aluminum and with the right speed/feed will cut yellow metals, superalloys, composites, etc. well enough. Get used to calculating surface speeds and make notes of what works well in what materials for that insert. Insert tooling is literally the best thing. As long as you don't outright crash the tool badly, you can gently caress up over and over again and only be out a $5 insert or two. Especially on CNC lathe applications. If you screw up just a little bit and manage to chip the face of one of the facets, you still have faces 2 and 3 to use, and on some inserts faces 4, 5 and 5 as well.
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Nov 4, 2014 08:24
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Wouldn't a triphammer be easier to engineer? Big weighted hammer attached to a big lever. Wheel turns, pushes the lever down, hammers falls, smashes fingers, wheel catches lever end again and the process repeats. Not much to engineer on that. Also a shitload easier on the bearings.
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Feb 18, 2015 20:29
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Ambrose Burnside posted:Personally I was digging the dies affixed to the flat platens with neodymium magnets, the sort of tool holder that will operate properly at safe pressures and do absolutely nothing when it actually counts. Since all the loading is normal to the face of the part, slippage shouldn't be too huge an issue? I thought it was a pretty clever way to mount the thing. Unsafe as gently caress, but clever. I'm eagerly awaiting followup where he either cracks it, or turns part of it into a short piece of ballista arm and launches something across the shop.
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Mar 4, 2015 18:24
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Ambrose Burnside posted:No and no to both. Waterjet guys are a good idea, though, I'll look into it, thanks Waterjet is literally magic. I've seen the higher pressure units cutting holes in 6 inch plate steel. Even the most economy versions of the things can handle 2" plate no problem.
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Apr 7, 2015 23:38
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Motronic posted:Go out an get some fresh flux core - it will make your life a lot easier and less splattery. Most fluxcore is hydrophillic, and will suck water out of the air. Then it makes a huge awful mess when you rapidly heat it to 3000 degrees. That's also the reason you keep sick welder sticks in the sealed metal cans until you're ready to use them!
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Apr 14, 2015 17:55
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Just a Fish posted:EDIT: New page, so to celebrate, here is some drilling porn for you all I don't get it. It looks like a piece of squished up flexible metal ducting that terminates at a cap in the ceiling.
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Apr 20, 2015 09:06
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Beardless posted:That's about what I figured, that a motorcycle would hold up to one BIG impact, but not as well to a series of smaller ones. Which is fine, as they're not designed or intended for that. Helmets are abrasion ablative and impact dampening, they go squish at a rate just fast enough to keep from smearing your delicate think-meats all over the inside of your skull, and wear down from rubbing slow enough to keep you from sanding most of your face and skull off as you slide to a stop They can do this exactly once. A helm will stand up to some astonishing levels of force, over and over again.
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Apr 28, 2015 08:04
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Random Number posted:The vacuum is an investment really. The leather apron is really situational and I'm just sperging out. I've only ever worn thick cloth aprons and they work pretty nicely for bigger chips and keeping your clothing safe from grease/burns. A good quiet shopvac and cyclone separator is literally magic when it's time to clean up stuff. 10 pounds of concrete and drywall dust? Gone. Cat litter? Obliterated. CNC enclosure full to the brim with bits of razor edged stainless or carbon steel chips? Vanished! And 90% of the crap ends up in the bottom of the cyclone bucket, which means I can run the fancy HEPA filter on my wetdry vac and not lose suction in 8 microseconds. Also, a good set of wrap-around eye-pro, or a set of gasketed goggles goes a really long way to avoiding bits of flying bullshit being magnetically drawn to your eyes. I have a 3M Ultimate FX I use for anything I don't want in my eyes and lungs, and it's comfy to the point where I can wear it all afternoon and not care too much.
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May 6, 2015 00:40
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Starz posted:The work is secured by clamping the perimeter of the sheet,which causes its' own problems. The boss doesn't want to replace the plastic table top so I have to put cardboard down underneath the work piece. Then when it is clamped at the edges it bows the center of the piece up a little and that messes with my Z-axis settings and I believe causes some of the problems with pieces wanting to shift more as they are cut free. It sounds like your workholding situation is poo poo. Properly and VERy rigidly holding the work is the #1 thing to look for on any job setup. The machine is already as rigid as it's going to get, but the workpiece isn't. Imagine trying to cut the end of a 2x4 cantilevered out with an axe. Most of the work in the swing goes into just bouncing the wood up and down. Same thing happens with the cutting teeth on a mill or router. It's why big metal working machines always have huge rear end vises and clamping systems to hold the parts down. Less part movement, more accurate parts, MUCH longer cutter life. If you can, and the sign allows for it, punch a hole in it and clamp the center to the table with a bolt and large area washer. That should flatten out the sheet and prevent the bowing from starting to hum or vibrate under load. If not, check clearance and just put a big rear end heavy chunk of plate steel on top of it. With thin stock, that's often enough to keep it from being an issue. Just make sure to air cut at 200% feed override ~2 inches above the part to make sure you're not going to strike it, because that can cause severe loss of blood and general sadness all around. Look into the spoilboard on the X-Carve or Shapeoko machines. There are 1/4-20 inserts in the MDF base plate you use to clamp down. Get a sheet of 1/2" MDF, add a bunch of those inserts to it, and you can clamp/screw and do whatever to it because it's a $20 chunk of glue and sawdust instead of a ~$400 chunk of plastic. Another thing to look into is getting a real vacuum table for it. You can get them with a pressure sensor that will E-stop the machine if the table loses vacuum, like if you accidentally cut through the material completely. Those are super handy for doing other poo poo while the machine makes the sign. Methylethylaldehyde fucked around with this message at 10:15 on May 9, 2015 |
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May 9, 2015 01:07
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Slung Blade posted:The non name brand ones can be fine, but do your research. Duty cycle is always my number one category, it is a good indication of how robust the machine was designed to be in the first place. 20% would be a babytown frolics welding toy, 60% is decent. Duty cycle can be expressed as % at rated current. I don't know many people who actually weld at the full 200A or 350A offered by a lot of the inverter welders, and most of them will be 100% duty cycle below about half the max rated amps. If they aren't being specific about it, assume the worst.
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Aug 1, 2015 00:16
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You can cut pretty much any triangular thread with a single tooth threadmill in fusion 360. I've done 1.5-12, 3/4-12 and odd NPT threads using mine. 3D printing is shittons easier though, and if the thread surface finish is too rough, you can always take a file to it and smooth it out.
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Mar 23, 2019 03:34
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Vindolanda posted:I think it’s really unprofessional that manufacturers won’t make a hardened mandrel and run off a few tempered clips for the exposure. I’ve got at least five Instagram followers and that makes me someone that any enterprise should be courting. 3d printing out of a resin or nylon might be your best bet here if you want new. That complex a shape with the built in curves won't be cheap at all to make. Two die sets, minimum, made from prehard steel and milled to an acceptable finish will cost you several thousand, easily. On the plus side, like ambrose said, you can make like half a million of them once you get the dies made!
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Mar 28, 2019 17:29
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Ambrose Burnside posted:Yeah, 3D printing is what I'd do too. That will necessarily involve pulling accurate dimensions for every curve and bump and subtle radius in that thing, and then probably doing a fundamental redesign that retains key geometries to accommodate being made from a far less ideal material with inferior strength/toughness. Nice part about 3d printing is you can very very quickly iterate on designs that don't work for a variety of reasons. And you can do poo poo that would be absurdly cost prohibitive on a stamped or milled part, like reinforcing ribs, honeycombs, and things like that.
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Mar 28, 2019 21:01
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Karia posted:I can comment on professional-level machines from a mechanical perspective. 2nding this. Glass scales give you an absolute incremental measure of the machine's motion, which eliminates ballscrew compensation, backlash, thermal growth of the screw and nut, and a bunch of other factors. In theory it provides you with an extremely accurate external source to drive the motion from, in practice, outside of specialty systems designed from the ground up to use the scales, you really don't see the benefits over just using the machine as designed. The motion systems on even an entry level Haas are miles above what you'll see on a hobbyist or converted machine. Every machine has a ball-bar test done on it, which uses a glass scale on some magnetic ball bearings to very VERY precisely check the machine squareness, backlash, ball screw comp, and servo tuning. You'll see results on fine motion to within 0.5-2 1/10,000th of an inch, and bulk motion cutting parts under load that are within 1-2 10ths. On stuff like EDM machines, Die/mold machines, where you're going to be cutting a faux leather pebble skin pattern into a set of injection mold dies, single digit microns are important, and as such the machines are designed to accommodate glass scales and the motion system is tuned for that.
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Apr 11, 2019 00:24
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Ambrose Burnside posted:Right now I use a hydraulic press to do sheet metal artistic work using acrylic dies and urethane rubber pads; i'm lucky enough to have a pressure gauge but even then no two pieces are the same, I get a lot of failed parts due to drawing too fast, etc. Without the gauge you basically guess as to where you're at, the only definite indicator being the snap of the sheet shearing because you, icarus-like, flew close to the 20-ton sun. You can get an electric log splitter, a load cell, amplifier set and some control electronics for like $5000. Get a VFD hooked up to the electric motor that takes 0-10v for the speed, hook the load cell up in line with the ram, and drive the whole thing electronically. The load cell gives you true force applied to the part, and can chase down a part that tends to yield or flow and keep applying more force until it levels out at some programed level, and the VFD lets you do a much more finely tuned job in terms of force over time and creep up vs. a simple relay that starts/stops the motor. Programming it all will be annoying, but an arduino or raspberry pi would be able to do the input/outputs without issue. If you wanted to be extra fancy, replace the poo poo tier induction motor driving the splitter with a used 2kw drive servo off some old CNC machine so you can start/stop/creep with it without the motor catching fire after you use it for an hour.
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Apr 11, 2019 22:57
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Ambrose Burnside posted:yeah, ive done some research and nobody has anything encouraging to say about trying to do something with fine control and repeatability with hydraulics, and that's people working with the right equipment for the job, not the cheapest equipment that can still achieve the job like i prolly will. hydraulics are a mediocre solution in every aspect except for that pesky thing where it's probably the only way I can get the tonnage needed within our budget. i'd love to do sth purely mechanical and make things easy but the easy ways to achieve that seem to max out at a couple tons How much tonnage do you actually need though? How large a part needs to fit within the ram assembly? What's the actual total stroke? You can do some fun stuff with a servo, reducing gearbox and an arbor press, but that tends to top out at like 3-5 tons. An electric screw jack would also work, and would be easy enough to retrofit a servo into. And yes, hydraulic PID loops are at best 'close counts' type systems without fancy valves and accumulators and other fun bits and gubbins.
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Apr 12, 2019 01:33
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Ambrose Burnside posted:20 tons minimum, 25 or 30 would be nice, but really we'll go as high as we reasonably can, money and press frame strength permitting; workpieces/dies top out at around 8x8" (but are usually significantly smaller, say 4x4") and shouldn't ever take up more than 6" of height; 12-16" of stroke is likely more than enough and lets us get weird with bolt-on tooling. It's the tonnage that makes things tricky (or at least restrictive on a budget); the other requirements are trivial. A proof of concept could probably be ~5 ton capacity and still be useful for small work/press-fitting/blanking and the like but isn't really what we want it for so I'm inclined to not settle for less than 20. Then you need to think about how fine a line you need between 27.5 tons and 28 tons. A load cell and a servo driven log splitter can get you 90% of the way there, and as long as your PID loop is stretched out over long enough, you can creep up on whatever value you need. The issue then becomes cycle time and dealing with all the fiddly bits involved in the hydraulic control loop. If going from 27.5 and overshooting to 28.5 over 10 seconds won't cause issues, then that would work quite well. Take a log splitter ram and mount it on a 30 ton pipe bender frame, set up the controls and go ham on it.
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Apr 12, 2019 08:13
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Ambrose Burnside posted:Is it for use on mills as well as lathes? Manual lathes can have an X-axis crossfeed with a 1:1 or 2:1 ratio depending on if they measure 'on radius' or 'on diameter', so DROs offer that dia/rad switch feature for the X-axis to accommodate both regimes. That's what I was thinking, but didn't want to just guess. The only thing that would give a weird 2:1 geardown like that would be if you had it set in lathe mode somehow.
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Oct 9, 2019 00:42
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Karia posted:Got curious and looked it up. There was a lot of pushback on Reddit so she posted some followup. I'm omitting a lot of self-agrandizement, the person seems full of herself and really obnoxious, but does seem to know what they're doing RE: basic process optimization. If the person is good enough to make all these changes competently without risking a crash, I'd say go for it. But I also wouldn't blame a shop for not trusting some new hire to mess with processes that work well enough regardless of how much experience they have on paper. That's all pretty straight forward stuff, but they hosed up by A) lying on the timesheet and B) Running the code without permission. Just because they're 3rd or 4th hand machines doesn't mean they aren't gonna cost a shitload to fix or replace on short notice when someone swaps the tooling around and now that 0.050 clearance becomes a hard crash. Running the sim in fusion side by side showing the slowass way the code runs now, and the hot new sexiness her code does, the boss can more easily see the cost savings. Bossman likes it? Great! Bossman says to shut up and get back to work? Sucks to be you, I guess?
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Oct 9, 2019 23:06
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mekilljoydammit posted:OK, I seem to have been unclear. No, there's no toolchain for that. You model the physical thing, possibly by 3d scanning it, 3d print it, then do the usual lost PLA/wax casting process. You can glue 3d printed sections together before casting it, but welding castings together is a tremendous pain in the dick, never do it unless you absolutely have to. Methylethylaldehyde fucked around with this message at 02:20 on Nov 19, 2019 |
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Nov 19, 2019 02:16
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Sagebrush posted:oh, okay, he was awarded 50 million dollars in a judgment against the syrian government. so he's a multimillionaire in the sense that the tsai ing-wen is the president of china. It's paid for by the US Fund for people harmed by Terrorism, which is funded by sanctions seizures. It's probably gonna get paid.
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Jan 5, 2024 07:06
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Leperflesh posted:what's the supply pressure on the lab gas? I remember using lab Bunsen burners in high school and you opened the valve all the way for just an adequate flame. Gas at the meter for your house is about 8" of water. The lovely little bunsen burner pipes in your HS lab are probably 1-2".
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Feb 9, 2024 23:50
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Hadlock posted:I'll save everyone the Google; For those who doubly don't want to do the gas flow and energy calcs, the lovely gasflow can still support a 3-4k BTU/hour bunsen burner, which is enough to do more less whatever lab you were assigned in class. Or burn little pieces of paper you folded up because you're bored and failed the lab because you hosed up the titration section.
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Feb 10, 2024 12:21
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Hadlock posted:I realize this is a very "how long is a piece of string" question but how many cuts do you get out of a band saw blade before it needs replacing? 100 cuts of 1" thin wall square tubing? 200? Just 10? Also for a bandsaw you want to follow the 'three teeth rule', where at any point in the cut, there are three teeth in the material. If you try to cut thin tube with a 4 TPI blade used for sawing wood, you're gonna bind the blade, break off teeth, or just snap the blade. For thin wall steel tubing, you're probably going to want a 14/18 blade. The chart here is pretty solid. https://www.bandsawbladesdirect.com/media/tech-docs/Tooth-Selection.pdf babyeatingpsychopath posted:We use a "cheap" horizontal band saw. I can usually get an infinite number of cuts in aluminum up to 6" in diameter, many many hundreds of cuts in mild steel of all kinds, and like, 10 cuts in 316 stainless. Fewer if no cutting fluid was used. We're also using the cheapest Grainger bandsaw blades and not actually setting the speed of cut based on material. I'm sure you could do better if you paid attention to that kind of thing. I had the Dewalt chop saw with that style blade in it, and it was an absolute beast for cutting solid aluminum stock. Downside is it's loud as gently caress, and the chips end up literally everywhere in a 20 ft radius. Tubes were really iffy, if you didn't cut it right it would bind and exciting/expensive things happen. We ended up getting the slightly bigger Jet bandsaw, and we're happy with the results.
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Feb 13, 2024 02:00
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WTFBEES posted:Not to hijack, but this saw conversation is very convenient as I'm also shopping for a way to do some proper cutting. Stainless exhaust pipe would be the first project with various future mild steel and aluminum projects to follow. Though I figure those two are a non-issue for anything that can manage stainless. That saw is 1400 RPM, with a 14" blade. That's a cutting speed of about 5100 SFM. Carbide tooling milling aluminum has a generally accepted cutting speed of 1400 SFM. The big blade gets away with the higher speed mostly because the total cutter engagement is like 5% of the saw's circumference. Stainless wants...200 SFM. If you tried to cut SS304 or SS316 tubing with that saw, you'd just smoke the $100 blade in a cut or two. In comparison, a real cold saw like this one spins at a blistering 52 RPM, which comes out to ~190 SFM, which is right in the sweet spot for actually cutting alloy steels and stainless. It's also $4000 vs. the amazon item's $500. I'd suggest a craigslist bandsaw for $500 instead.
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Feb 13, 2024 03:05
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Sagebrush posted:6. Realize that you want a bigger and more rigid mill, and a flood coolant system, and a spindle speeder, or maybe an air turbine... Suddenly realize that you're now *boat money* into your hobby, but that's okay because at least you weren't dumb enough to buy a boat.
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Mar 16, 2024 00:26
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