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AlexDeGruven posted:So I've been working on doing some resin casting in silicone molds. And I have been designing/printing the 'negatives' for the silicone mold. I’ve been designing and making directly-printed metal casting molds from high-temp-resistant engineering resins, so sort of the literal mirror of what you’re doing i suppose. Nice to find someone else using hobby resin printers for technical/production work, it’s incredible how many doors a $300 machine opens when it lets you one-button print any high-detail model you want if it’ll fit on your build plate. i post my stuff in the other bigass 3d printing thread in diy, check it out some time~ out of curiosity, how do you seal/treat your models so they don’t interfere with the silicone curing? that’s one of the biggest hurdles to using resin printing as part of a silicone mold making workflow.
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Jul 19, 2021 21:12
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AlexDeGruven posted:I'm doing fdm to make the molds for the silicone molds for epoxy resin. i missed that, whoops. yeah that’s much simpler, thermoplastics don’t poison the silicone cure process like basically “all” acrylate resins apparently will, there are a bunch of surfacing/passivating techniques people apparently use but i haven’t tried em myself
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Jul 19, 2021 23:24
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InternetJunky posted:I had to switch to Eryone last month because Siraya's Canadian stock ran out. I bought all the Eryone grey available, and now I'm printing in a vivid peach colour because that's all they had left. Siraya's stuff is/was in customs warehouse purgatory, they post updates with dates on their FB group- there should be lots of inventory coming through 'soon'.
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Jul 21, 2021 20:43
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InternetJunky posted:I'd like to talk about nitrile gloves for resin/print handling since as an alternative I'm actually using super cheopo sandwich gloves similar to what the workers at Subway would use (https://www.amazon.ca/Ronco-Deli-Medium-Disposable-Gloves/dp/B00QEGN8TE/ref=sr_1_10). Most of the time the glove is on for about 10 seconds total (take off flex plate, scrape off prints, put plate back on) and using a nitrile glove for that becomes kind of expensive if you print a lot. They are also great when taking the vats off the machine, since I can take the vat off with one set of gloves and then quickly put on clean gloves and not risk accidentally transferring uncured resin from the gloves underneath the vat. yes, resin actually does penetrate the thin porous material gloves are made from. 15 minutes is the max glove contact time you should have to chemicals like this. you’re not poisoning yourself but you’re absolutely priming yourself to develop a sudden severe and irreversible sensitivity to the resins that (iirc) you pay the bills working with. people who work with resins and epoxies for a lifetime have an almost 50% chance of this happening at some point, the more contact you have the faster it happens, and it generally forces people to change jobs/careers. Get nitrile gloves and change them frequently. Like, a pair shouldn’t be on your hands for an hour if you’ve gotten resin on it, this stuff can and will penetrate all thin stretchy gloves, it’s just a question of speed and degree. this is the worst part of this to cheap out on. Paradoxish posted:Going through a ChemE degree filled me with enough stories about the consequences of treating "mostly safe" materials without due respect that I won't go near my resin printer without gloves, long sleeves, and a mask. this is the right attitude to take, yeah. it seems overkill, but resin sensitization is a statistics game, if you wanna do this for years to come you need to give yourself every advantage. it’s not actually that expensive or difficult to boot. Ambrose Burnside fucked around with this message at 17:58 on Jul 22, 2021 |
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Jul 22, 2021 17:55
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InternetJunky posted:This is good to know -- I have never heard of resin sensitivity being an issue that could develop. That being said, for myself I'm changing flex plates 15-20 times a day and the plastic gloves are on my hands for 10-15 seconds max. For actual stuff like support work and cleanup I use nitrile gloves. if you’re constantly shedding gloves immediately every time you do The Resin Contact Step you’re honestly probably good, even if the gloves you’re using offer poor protection from chemicals. i’m also not sure the extent using a non-stretchy glove helps, but it probably does, the stretch of nitrile/latex etc is the main thing making those gloves so readily-permeable. the bigger issue is with people repeatedly reusing nitrile gloves, or getting resin on them and wiping it off and continuing to work for however long, not using gloves at all for “just touching it for a sec”, that sort of thing. Just, yeah, acrylate resins are aggressive sensitizing agents, and once/if that happens it can put a serious damper on you working with that material at all going forward, it’s huge, permanent and largely-preventable bummer.
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Jul 22, 2021 19:18
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I'm designing a cast metal part with a significant interior threaded section that's impossible to produce with the usual hobbyist techniques, so i'm gonna be attempting to directly print a dovetail collapsible mold core in Siraya Sculpt Ultra soon, which I've never attempted with the usual CNC machining nor printing. one of these things-  real pain in the rear end to manufacture well by any method, its a ring of thin dovetailed sliding members bearing the casting impression on their outer face that all mate with a tapered dovetailed core in the center, the idea being that inserting/withdrawing the core will smoothly shrink or expand the core, making it possible to mold very challenging features that would otherwise be impossible to demold without breaking the tool. anyways, not only do all the dovetail joints need to mate with very close tolerances, the individual sliders have to run straight and true without any warping/bowing, and the sharp edges on the sliders needs to be as crisp as possible so I don't get huge mold flashing lines all over the inner bore of this part. any tips for best practices here assuming a resin printer? I'm thinking print all components vertically, the 'slow' way, and maybe use support 'towers' alongside/surrounding the thinnest parts, to give some additional support and to provide a supporting matrix of sorts to resist warping during the post-cure. Also probably gonna need to run through a couple prototypes and do a lot of hand finishing to get an acceptable fit-up, but that's a given with any tool like this.
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Jul 23, 2021 19:36
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NewFatMike posted:Ambrose, if you care to share, I would adore seeing those CAD files when you're done, regardless of whether it prints well. there’s a couple decent examples i found on grabcad, they’re actually fairly straightforward to design once you have the core geometry locked in, it’s just the dovetail sketch lines projected with a slight triangular taper to split the core up into the 6 slides and the single core. there’s other ways to make collapsing cores too, there’s another technique that uses just two intermeshing parts that each resemble an ER collet-sorta slotted thing with flexible fingers. the dovetail core approach is more effective and much more robust a tool, it’s just more involved to machine. also you can just make it without the dovetails, which is what they do for very small-diameter pins where dovetails aren’t practical. then you get a core that needs separate accommodations to hold it assembled in place, and which isn’t automatically self-retracting with a simple pull on the core pin, which frankly i don’t really need for a non-automated molding process. worth trying it the fancy way first b/c it takes no extra effort to do so biracial bear for uncut posted:Also an odd article/paper someone wrote about it. yeah, this looks like the two-part core approach, with a core collapse/demolding aspect (the lever-action bit). i’ve found better documentation of this approach and i suspect it might be little easier/quicker to design and print, but a fragile tooling approach in tool steel might be just non-viable in a fairly brittle resin. Ambrose Burnside fucked around with this message at 17:47 on Jul 24, 2021 |
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Jul 24, 2021 17:36
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Randalor posted:What's a good, easy to use, free program for 3D modelling? Or at least low-cost if free isn't an option? Hard to recommend a single product without knowing more about what you wanna do with it, what the end application is, what kind of learning curve you’re willing to deal with, etc. Fusion360 is the most likely answer to your question, but I would check out the CAD megathread I posted a while back, it may tell you what you want to know- https://forums.somethingawful.com/showthread.php?threadid=3962532
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Jul 27, 2021 03:27
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OpenSCAD has a teeny tiny "genuinely the right tool for the job" niche that will not come up for most people, and its CAD functionality is extremely primitive. Also it's a nightmare to use if you're not a programmer first and foremost. Sketchup has absolutely nothing going for it in 2021 for this purpose. Blender doesn't sound like a good fit for your needs either, although it ought to be capable of what you want. Just grab Fusion360, imo, it can do what you want in a straightforward way but is much more powerful if you want to start making better designs (once you fillet up a blocky model for the first time you'll see the appeal of a more robust CAD platform, even if you're mostly working with primitives.
Ambrose Burnside fucked around with this message at 18:37 on Jul 27, 2021 |
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Jul 27, 2021 17:24
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attempting to print my first collapsing core for a metal-casting mold. i'm designing a lil cigarette case as a gift for someone- think an ornate cigar tube sort of deal- and if i cast it as a single cylinder like I want to vs. making two clamshell halves and welding them together, the inside cavity is a challenge- it's a long, narrow tube that's closed at one end, and because the inner diameter is what matters I can't just taper the core, the tube is long enough that a useful amount of draft can't be added. anyways, collapsing cores! starting simple, just a two-piece assembly here. both should print upright on the bed with no issues  here's how it works- you withdraw the inner core, which is very slightly tapered to facilitate this, and as you do so the 'sleeve' 'petals' can flex inwards, deflecting past modest undercuts of the sort you can't normally locate at the bottom of a deep blind hole when designing a cast part. a smooth tube is pretty easy, threads are pretty easy, i think undercuts up to 10% of the hole diameter are possible with this design. i need to break out the dovetail cores if i wanna do massive 25%+ undercuts or whatever 
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Jul 28, 2021 00:47
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withak posted:Yeah “cigarette case” sure lol. once upon a time i used to manufacture sex toys, the current “anything involving penetration needs to be anodized” title for metalworking thread was from one of my posts. if that's what i was making i would be extremely loud about it b/c making toys rules Ambrose Burnside fucked around with this message at 01:44 on Jul 28, 2021 |
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Jul 28, 2021 01:40
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Trying out my first resin print w high-speed settings (240mm/min for all lifting), never a better time than “a birthday gift print just failed twice and now it’s the day of”. it’s going ok so far but the loud (by resin printer standards) knocking every time the build plate zips off the old battered FEP film was… concerning, at first. now it reassures me from another room that the print hasn’t failed yet.
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Jul 29, 2021 19:35
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InternetJunky posted:I'm constantly topping up vats while printing so I guess I'd have to premix, but that just seems like it would be a massive mess with mixing cups and funnels and resin dripping everywhere. I'm curious enough to give it a try, but is there actually a measurable difference in durability when you mix in 10-20% flexible resin? the easy way to blend resins with a constantly-topped-up tank is to go by weight, you don’t have to use any measuring cups or anything like that if you’re clever about it: - get a scale with 1g or preferably 0.1g resolution - weigh a resin tank when completely empty, make a note of that figure - weigh a resin tank while completely full at the max level you’re liable to work with, subtract empty tank weight from full weight to find the ‘maximum fill weight’ sans tank. write that down too. we’re assuming all resins weigh the same which is not true, but is true enough to not distort the results by more than a fraction of a percent for most resins so we can ignore it - mix your initial blend by weight, dividing the maximum mass into the proportions of resins you want to combine. i usually mix a little less than a full batch, maybe 90%, to leave some wiggle room and to prevent me having to choose between overfilling the tank or settling for the wrong proportions because one of the resins was less dense than anticipated or w/e - next time you want to top the tank up, weigh the partially-full tank and subtract the empty tank mass to be left with the partial resin mass. subtract that from the max fill and you get the total resin weight required to refill the tank. divide *that* into the resin blend proportions to get the required refill weights for each resin - put tank on the scale, tare it so you’re starting from zero, and add the required resins to the tank no extra mess or handling, and it lets you maintain a fairly consistent product from part to part despite being a veritable acrylate resin pot-au-feu Ambrose Burnside fucked around with this message at 14:36 on Aug 4, 2021 |
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Aug 4, 2021 10:50
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Do any of these new alternative resin vendors offer niche-y engineering/casting/mechanical resins, or just figurine modelling/‘abs-like” common offerings? i’m not wedded to siraya but i don’t think there are any alternatives to specialized stuff like Sculpt Ultra.
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Aug 7, 2021 05:30
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I’m a resin guy so i’m shooting from the hip here, but (aside from material choice) the difference between a budget nozzle and a premium nozzle is largely going to be finish quality and consistency, right? So why not treat this like any other roughly-finished tool and just do the final finishing and QA yourself? I figure you have a couple ways to skin this cat, even for the small nozzle diameters; either a fabricated reamer or an abrasive solution should work and be quite accessible. the reamer will give better and more controllable results and you only have to make a tool once for a given orifice diameter, while the abrasive cord requires basically no prep but is less controllable and will favour abrading the orifice ends over the inner bore. - Delicate ‘finishing reamers’ are very easy to make if you have the right size of drill rod, you just make one cut where you grind a flat into the rod face at a fairly steep angle to produce a large oval ‘flat’ that tapers to a fine circular edge. they can remove very little material but they work well in a hole that just needs cleaning up, and theyre trivial to make yourself even with hand tools. Wish I could remember the proper name for them, I know instrument makers use them to finish the long inner bores of drilled woodwind instruments and the like. i would attempt this, assuming zero metalworking tools or knowledge, like so: buy a teeny tiny drill rod metric spread/find a broken drillbit shank in the right diameter, also find myself a sharpening stone/fine wet sandpaper on glass sheet/diamond lap etc etc, plus a boring old pink/white eraser. then i’d stick the rod through a the at the desired angle to ‘lock in’ and constrain the grinding angle for you, withdrawing it so only the edge of the end face is proud of the eraser block. then i’d tape over the block sole or wrap it in something so it glides freely over the abrasive. apply a few drops of water or oil to the abrasive block as appropriate, and make sure the rod is in the fluid puddle. now you can go to town sliding the block across the abrasive, applying light pressure from the end of the rod to keep it engaged. once you have an oval flat across the whole rod with sharp hair edges, you’re golden. - the other easy option is abrasive cord; they sell 0.012” impregnated cord on mcmaster carr for, like, $12 for 200 feet, i’m sure you can get it even cheaper elsewhere, and that should fit through most / all nozzles, right? this would do a very quick job of removing- or at least normalizing and reducing- any flashing or irregularities inside the bore and will let you put a very gentle, organic chamfer on the open ends to take care of any burrs. i can think of other ways i’d do this but either of the above probably cost like $20 to implement and don’t really require much else in the way of resources or skill sets e: oh yeah, you’ll probably also need a jeweller’s loupe or other decently-high magnification to actually inspect the nozzles and determine what needs fixing Ambrose Burnside fucked around with this message at 20:32 on Aug 17, 2021 |
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Aug 17, 2021 20:17
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Serenade posted:Finally got around to getting a wash and cure station, taking the chance to re-evaluate my post print process. i use fireplace fuel and am very happy with it, it's an ethanol-isopropanol blend that only has a small fraction of ISO (less than 10% iirc) as the denaturing agent. i find it cleans better than pure ISO, it only costs like $30 for a bigass multi-litre jug at the hardware store, and as a nice ancillary bonus it's safer to use because its flame is highly visible compared to ISO's (which is a dim blue that's often near-invisible in well-lit environments) acetone is extremely effective and even works well even on extremely persistent engineering resins that usually require brush-cleaning after an alcohol soak, but i wouldn't use it if you have your printer in your home/don't have a dedicated ventilation setup for your workspace; it's a lot more unpleasant to work with, but it's also far more volatile/has a vapor pressure at least 5x alcohol's, which means it will get into the air in a greater volume and will bypass the lid gaskets in wash tubs much better. if you're working with resin indoors you should always have an eye towards reducing VOC emissions, not increasing them.
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Aug 19, 2021 20:56
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insta posted:Fabreeko is selling ender 3 returns for $99 if anyone wants a second printer. i’ve never been quite able to justify “bigger and cheaper, if cruder, prints” enough to get some FDM goin to augment my resin, but at that price point, well heck
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Aug 21, 2021 08:02
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Anybody know of a good practical photographic comparison of the fine print resolution between 50/47 -micron pixel standard-res printers and 35 micron ‘4k’ printers? and/or between older color screens and mono screens? i’m running into the limits of what my Mars Pro can accurately represent for tooling/molds at very small scales and i wanna stoke the fiscally-imprudent “buy a sonic mini 4k” fires in my loins.
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Aug 22, 2021 17:47
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csammis posted:edit: I genuinely considered when I made that post writing something like “the differences may not be visible to the human eye but thread poster Ambrose Burnside might care about it for incredibly small tooling” yeah i can’t imagine getting much from the 4k upgrade for tabletop miniatures or whatever, but for molded part details like embossed lettering (which requires deep, sharp-cornered pockets in the tool), i actually can’t go nearly as small as i’d like to before everything starts bleeding together and getting mushy. i have never heard of a color screen Elegoo printer getting upgraded to mono by the end user, else id just start with that.
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Aug 22, 2021 23:27
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on that note, 2/4k isnt actually an informative statistic, absent more information, right? it’s more a marketing thing? like i see “4k” get applied to both genuinely higher-resolution printers, as well as those with standard resolutions but a larger print area, and the raw pixel count is the same in both cases.
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Aug 22, 2021 23:59
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Anybody seen Sirayatech Sculpt Ultra available for sale, like, anywhere? Or a comparable product? I'm being extremely conservative with my current bottle because there doesn't seem to be a comparable substitute product for high-temp applications like mine, and Siraya doesn't seem to be in any rush to produce more of it after the initial production run. The original Sculpt is probably the closest thing to it I can find, but even sculpt's 160C temp rating won't cut it for my application.
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Aug 28, 2021 21:36
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w00tmonger posted:Possibly you complaining, but this was brought up on Facebook by someone and frankly I've lost all faith in sirayatech to carry a product consistently Hadlock posted:There is extremely limited capacity shipping from china -> us west coast right now fwiw someone else directly asked siraya tech about Ultra a few days ago (apparently a big-volume engineering part printer who also wants 5kg jugs of the stuff- i guess there’s some bona-fide demand there?) and the company rep said their latest batch should hit amazon in about 10 days. The shipping issue does seem to be at the root of all their problems lately; ST’s Canadian warehouse has had no stock of anything except Build for over a month and a half at this point, and people are noooooot happy about it. So yeah, I’m not despairing about Sculpt Ultra access yet, esp after hearing that some people are using it for high-temp applications in a big way after just one or two exploratory batches of the stuff. It’s still $120 CAD per litre from Amazon, though, so I should probably see where regular old Sculpt can reasonably substitute for pure economy reasons.
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Aug 30, 2021 18:10
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Blu on its own is a rather bad fit for miniatures, especially if you don't have a heater for your resin tank- it's relatively low-detail and is notoriously challenging wrt quality control. when I try to print it "like any other resin" i get a near-100% failure rate; I usually have to heat the resin, use a special super-gentle settings profile reserved just for Blu, and/or use a special extra-chunky support profile also reserved just for Blu. often a combination of the three. I don't use Blu unless it's gonna be a mechanical part, it's too big a pain in the rear end + has poor definition and low dimensional accuracy on certain areas of the print, such as the underside near the support roots. I wouldn't assume the resin's age is the culprit if you haven't ruled some of the Blu-specific issues out. Also fwiw a bit of Blu blended in a more typical resin can significantly improve print strength + toughness without being such a bear to print. SirayaTech still makes a good product imo, for miniatures I would go with Sculpt, it's got the best fine-detail definition and surface finish I've seen in a resin so far. ST Fast gets good reviews as an all-around modelling resin, and it's a fair bit cheaper than Sculpt.
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Aug 31, 2021 21:29
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What's the thread consensus on screen protectors? How many people actually use em? I never have, partially from laziness but also partially b/c they increase bleed by a non-negligible amount (or so i've heard), but then again i've also never torn a FEP sheet or even had to replace a sheet yet; according to my .ctb working file archive, this ingot mold i'm running now will be my 107th print without issue, which does not seem typical
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Sep 2, 2021 04:44
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Acid Reflux posted:A spare FEP sheet and some kapton tape makes an excellent cheap screen protector that's guaranteed to not filter any UV light. Barring that, even just some kapton tape around the border of the screen to seal the gap (if your printer didn't already come with tape or a vinyl gasket) goes a long way toward keeping resin from oozing inside the machine in the event of catastrophe. I also have never broken a FEP sheet, nor have I had to change one in any of my printers yet after quite a lot of use. A little bit of care and attention goes a long way. Accidents can obviously happen though, and I'm no more immune from that than anyone else, so my screens are still taped/gasketed just in case. Taping around the screen gap sounds like an excellent compromise, i’ll give that a whirl.
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Sep 2, 2021 19:46
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wrt resins, if you can't vent to outside, a recirculating filter design (that draws from, and vents into, the enclosure) is much better than the once-through filtered ventilation that printers often come stock with. i designed a huge one that accepts Blueair Smokestop filters (they're specialized for scrubbing VOCs vs. a generalized standard filter) but it's a part of a larger enclosure i haven't started in on; in the meantime I'm inclined to build a much smaller recirculating filter that i can just graft on to my Mars Pro's stock enclosure hood, at least that's a quick weekend project I'm likely to tackle in a timely fashion. As a guiding principle- if i can't possibly vent to outdoors, contain it. I want everything that comes into contact with resin sealed away from my living space at all times it's not actively being worked with, so how i work and particularly how i store all my materials and resin-working tools is also a big part of my 'ventilation' strategy. all the scrapers and spatulas and silicone workmats etc go in gasketed latching bins once i've wiped them down, resin-bearing garbage gets cured promptly and fully disposed of often, any spills or even smudges of uncured resin on bench or floor are cleaned thoroughly with alcohol, i use a shopcoat when doing printer stuff so i don't accidentally track it around on my clothes, etc.
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Sep 7, 2021 01:08
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Where should I be spending my money if I want a wash n cure unit? My DIY setup is pretty ragged at this point and I think I'd rather upgrade than rebuild it. I'd also prefer something smaller rather than larger because table space is at a premium, as long as it can accommodate a Mars Pro build plate and/or flexplate plus attached prints. Also, are there any limitations with using a wash/cure that would push me towards another DIY solution? I'm currently curing my prints under water, that's still an option with one of these setups, right? Also, i
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Sep 10, 2021 20:46
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the one issue i see is how using a multi-step washing process will require additional wash bins, and those suckers need a lot of alcohol + take up a lot of storage room compared to 1L pickle jars. also pretty pricey as aftermarket parts. still worth not having to handle uncured parts directly
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Sep 10, 2021 23:20
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Bodanarko posted:When the first wave of cheap MSLA printers came out (2019?) it was common practice to UV cure cleaned prints in water, due to the belief that oxygen inhibited the curing process. Still how I do it though it seems that everyone has moved on from that. Siraya still recommends this for many of their resins, while specifically forbidding it for a handful of others. IME it 100% eliminates the atmospheric oxygen scavenging problems that cause tacky prints / partial curing, and generally helps a lot with quality control, so i default to it unless i have a good reason to do otherwise. The exact compositions of resins are critical trade secrets for these companies, so i’m shooting from the hip here, but i get the impression that modern “fast/easy” formulations have some component that carries its own curing issues when in contact with water that offset the scavenging issue advantages- ST says prints using its Fast resin need to be 100% dry when UV curing or unsightly surface defects will result. Blu and Sculpt Ultra, meanwhile, have warping and tackiness issues almost half the time when water curing isn’t used, ime. in principle, using a shielding gas instead of water for curing would be ideal, never seen anybody attempt it, though.
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Sep 11, 2021 20:52
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Bucnasti posted:I hope it doesn't take long for larger DLP printers to become available. That Ultra just has too small a build area for me to justify replacing my Mars 2. I wouldn't hold my breath for things getting much bigger than the current-gen Big Boys, or at least not for a hobbyist-friendly implementation. DLP x/y form-factors are unique in being a direct reflection of, and tightly constrained by, the mass-production of ultrahigh-DPI displays for phones, and I just don't see larger screen form-factors becoming popular enough in consumer electronics to bring that sweet sweet economy of scale hobbyists crave. I know this has changed a fair bit in the past year or two and manufacturers aren't at the same mercy of phone hardware selection as they were when the first crop of really mature hobbyist DLP printers were being designed, but i don't think the underlying dynamic of "shockingly-cheap phone displays are effectively subsidizing hobbyist resin printers" has changed significantly. getting stupid with the z-axis, though? that's more or less as simple as just using longer linear ways in a cartesian FDM printer to get a bigger print area, which is an addressable engineering challenge instead of an untouchable global-markets-level one. i'd definitely like to see more z-axis silliness, mallsword and fancy cane-specialized printers or something, in large part b/c it's cheap and achievable using the parts manufacturers have already sourced cheap and in volume Ambrose Burnside fucked around with this message at 00:17 on Sep 15, 2021 |
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Sep 15, 2021 00:11
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Fantastic Foreskin posted:Can you not get/use like industrial chemical resistant gloves? The super thick kind. i explored this a while ago b/c I wanted to use the 'right' barrier material for acrylate resins, nitrile is better than latex but still isn't indicated. I got heavy butyl rubber gauntlets but didn't use them long b/c you end up tracking resin all over the place, they become tacky and stay tacky no matter how much I tried to clean them, just a big pain. Disposable butyl gloves exist but cost a couple dollars *per pair* so that's not realistic. I'm on InternetJunky's wavelength right now, TPU gloves are super super cheap, tough and tear-resistant, very easy to put on and take off, etc. did i mention cheap as sin? changing gloves whenever you touch resin is the name of the game here and my tendency is to be a little stingy with decent nitrile gloves so i'll go with whatever steers me towards best PPE practices. On that note, I haven't been able to find any specific info about the suitability/compatibility of TPE with acrylate resin like you can find for nitrile/latex etc, if anybody runs into that please post it.
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Sep 15, 2021 18:27
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Doctor Zero posted:aren't those clear? You could cure them too, if so. They are, that's a good point. On the subject of curing resin-bearing waste, an auto-curing wastebin would probably be easy and straightforward to set up, you could embed the whole thing in the lid. Have some 405nm LEDs on the underside of the lid, a microswitch that closes on the bin body/rim when closed, and a basic circuit that automatically runs a 30 second 'cure cycle' every time you open and close the bin. It'd go a long way towards curing all your waste without requiring you to take any extra steps or handle uncured resin more than is strictly necessary. I suspect maybe 1 out of 10 people who know you should cure your print waste actually consistently do so, so just passively making it happen via your resin trash can would do wonders in that regard. Ambrose Burnside fucked around with this message at 21:37 on Sep 15, 2021 |
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Sep 15, 2021 21:34
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a buddy of mine is getting clean and was complaining about how alcoholics anonymous has a monopoly on sobriety coins, so i'm designing an independent series of milestone coins, and also the Sculpt Ultra tooling required to cast them from a bismuth-tin alloy     it's an inch long along its long axis and 0.1" thick, btw. the casting isn't great b/c i poured it cold and didn't preheat the mold enough, and it's so small that i'm running into the limits of what my printer and exposure tuning can get good definition on- see the '1 week' text, the letters just filled in from UV bleed, but i'm hype so i'm posting it anyways; the mk2 coin will be at least 25% bigger to help in the crispness department. once i have a base design that i'm happy with i'm gonna make a big multi-core mold that can cast an entire series (5-10 'durations', from 24 hours to 1 year+) with one pour.
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Sep 16, 2021 15:20
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lol that's... not surprising. not currently planning on selling these but i'll be careful / do my research if i change my mind. it helps that i've deliberately stayed far away from any of the AA/NA phrasings/ideas
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Sep 16, 2021 15:29
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i'm pretty sure my workflow would open up an entire currently-untapped market of very small-run custom coins/medallions, not just for recovery stuff but more broadly... gonna circle back to this once i'm getting nice crisp coins from molds that survive more than a handful of pours. i’m having issues with maybe a quarter of my Sculpt Ultra prints spalling and cracking on first use with hot metal, maybe i need to bake them first to drive off any entrapped moisture or sth like that
Ambrose Burnside fucked around with this message at 16:06 on Sep 16, 2021 |
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Sep 16, 2021 15:52
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i tried something interesting and it worked way better than i expected. a cast-metal conventional cutting tool, cast from a reusable 3d printed mold. specifically a 'd-reamer' or 'd-bit', so called because of the shape you cut/grind into a round bar to produce the tool, here's a conventional steel example-  for those who don't know, reamers are precision hole-enlarging cutting tools. they cant drill their own holes, they can't even significantly enlarge a drilled pilot hole, but they can remove a very precise and repeatable amount of material, which is critical for any sort of precise fit-up where an exact type of fit is required. d-reamers are the only reamers you can make yourself without a proper machine shop available to you b/c of their simplicity, but manufacturing them still requires skilled and delicate grinding work (or hours of hand-filing), correct tempering of steel, etc- so you still need a decent workshop setup to make even the simplest d-reamer. and without a lathe, you're limited to the fractional/metric sizes of round rod you can buy off the shelf, which largely bars you from making the really useful reamers, i.e. a 0.124" reamer for producing a locking interference fit with a 1/8" dowel pin, or a 0.126" reamer for a precise sliding fit with zero play, etc. or any sizes that sit between the bar diameters you have available. so they're still really in the realm of machining, as accessible as they are. i give you: zero-machining-required castable bespoke reamers, for precision holes in your printed parts. for a sense of scale, the head of the tool is a little over 1/8" in diameter, the shaft about 2 inches long.  i cast this into a cold, already broken mold i held together with clamps. i haven't cleaned the casting up at all, this is how it came from the mold- shows off the excellent surface finish and detail capturing this approach is capable of, when everything re: the casting lines up. i'm using a thermocouple to take the molten metal's temperature now and it helps enormously in pouring at the right temperature, I think that's gonna stop being a problem for me. by the way, i melted the charge for this using a tea-light candle and a steel ladle, that's how bare-bones you can go for small castings using this material.  best pic i could get of the cutting head, showing how limited the flashing is and how it captured all the small details i modelled into the tool, like cutting nose radius, a small flat behind the cutting edge to provide a bit of cutter relief, etc. the only cleanup required was a couple swipes across the 'flat' of the tool with a fine-toothed file, produced a flat face with crisp cutting edges in about 10 seconds:  i modelled the tool at 0.135" cutting diameter but didn't get the UV shrink-compensation mold scaling quite right, the cutter ended up measuring 0.140" dia and reams a 0.135" hole out to 0.141", as per my calipers- i have a micrometer but haven't broken it out yet to get a more accurate reckoning. i have only tried this tool on printed resin and would not expect it to be useful for much of anything else, any metal will be harder than the cutter and most woods would probably blunt the tool too rapidly. this cutter shows visible wear after reaming a couple holes; a side benefit of the d-reamer design is that sharpening a tool requires only a single large flat to be ground, which means you can 'refresh' the tool's edge repeatedly with said metal file before the cutting diameter changes significantly. to be clear, this is an atrocious reamer by reamer standards, barely worthy of the name. it is a potemkin reamer, a facsimile of a tool with the correct geometry but rendered in a laughably-weak material. the reason this is still compelling is because: - it is absolutely the easiest reamer to make i have ever seen, and the technique can produce any required diameter of reamer you can print a mold for, accurate to one or two thousandths of an inch assuming an entry-level resin printer and good print QC, and requiring no special skill or knowledge on the part of the fabricator beyond 3D printing stuff and the know-how to tweak a parametric reamer model to suit your needs; - the material is still hard enough to be a useful short-run tool for reaming out holes in printed parts; - the fact that it is cast from a low-melting alloy means you can easily melt and recast worn-out tools, or cast a whole bunch in anticipation of many holes for a job, then melt em all down afterwards and recapture the metal for reuse in a near-lossless loop. also- this tool uses a lead-free tin-bismuth alloy, but I could make a significantly harder and stronger tool using a tin-bismuth-lead-antimony alloy i also have a couple pounds of. the only issue there is there's some shrinkage in the hours and days after casting with that alloy, so the tool's diameter increases appreciably for a short time after manufacture, but by no more than ~0.006" per inch, and that can be planned around via mold scaling. i'm mostly just avoiding contaminating everything with lead until it's unavoidable. another thing i considered is embedding a small steel hex wrench within the shaft of the tool, it could be positioned quite accurately by the mold geometry, but I haven't found it necessary yet, reaming plastics is p low-force. Ambrose Burnside fucked around with this message at 05:14 on Sep 18, 2021 |
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Sep 18, 2021 04:27
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NewFatMike posted:Holy moly! Would you be willing to share models? I bet that would be a *huge* hit at my makerspace. here's someone's grabcad d-reamer that looks good https://grabcad.com/library/8mm-straight-d-bit-reamer-1#! this shows the needed general geometries from a couple perspectives. the 20-degree relief isn't necessary for a reamer, but is for a self-drilling d-bit (which I don't think is worth attempting/has no utility for a hobbyist with twist drills aplenty)  here's a dimensioned print for a tapered reamer, note the important 2 thou offset from the centerline, without that the tool will bind uselessly  ask in metalthread for general reamer design help, lots of machinists in there re: melting, BMan posted:he said a tea light i did in this case because it was a very small casting, normally i use a hot plate and small enameled pot to melt up to a pound or so, never needed to cast anything nearly that large yet. currently building a PID heat controller so i can hold the melt at a very specific temperature + preheat my molds, these alloys can be picky about casting conditionsif you want optimal surface finish/mold penetration. with proper mold preheating you can cast some very thin and/or high-detail parts, i've used a heatgun to rough preheat my molds previously but i expect to get much better results with a nice PID-regulated oven soak Ambrose Burnside fucked around with this message at 05:44 on Sep 18, 2021 |
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Sep 18, 2021 05:37
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re: alloy choice, i'm using what's called "cast 302" here http://csalloys.com/specifications.html- it's very hard for a tin-based alloy, which is critical for keeping a useful cutting edge for more than 10 seconds, is lead-free, has acceptable strength/stiffness, and has almost perfect dimensional accuracy post-casting, so sizing precise things like reamers is significantly simpler, you only have to control for resin shrinkage in scaling. melts around 300F, so it can be cast into high-temp resins like Siraya Tech Sculpt Ultra without damage; the molds should be reusable many times if properly made. what they call "matrix alloy" in the extended spec chart is my lead-based tooling alloy i also purchased a supply of, it's over twice as strong as cast302 and just as hard. it doesnt make much sense in this application but it's killer for stuff like hydraulic press tooling because it can take many tons of force per square inch without creeping, something lead-bearing alloys are usually prone to i've been developing a rapid tooling process based on these alloys for a while now, i posted a shitload about it in the last (now locked) 3d printing thread e: also i've seen other people directly casting pure lead or bullet alloys into Sculpt Ultra molds, making air rifle pellets and such, but that seems to fly a little close to the sun, you're working well past ST's reported heat resistance for these products, heat damage seems not-uncommon in the tests ive seen. that said, ST's rep told me they significantly lowballed their temp ratings, so who knows what Ultra in particular is really capable of, esp with thick n robust mold walls (the claimed temp resistance is for a 4mm thick flat section). i should give it a try some time, design some gimmicky wildcat .177 pellets as an excuse to cut a real-world pure lead mold Ambrose Burnside fucked around with this message at 12:44 on Sep 18, 2021 |
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Sep 18, 2021 05:47
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yeah yeah yeah ok its comin together  i dropped the goddamn mold and it broke into 5 pieces so i held it together w kapton tape. which actually worked great, it doesn't sweat at all at the temps im working at. tightly wrapped it has a good all-around clamping action, prolly gonna keep using it   still having some infill issues on the lettering, i think it's b/c i poured at 425f and let the mold sit out for a while after preheating. once my PID oven is working i'll get a really tight control over all these variables, im hype also i tried doing a hammer-peened bumpmapped mesh texture on the face of it but it doesn't look like anything in particular b/c i tried representing a .15mm tall feature in just 3 .05mm slices, alas. maybe i finally have a reason to go w extra-fine z steps Ambrose Burnside fucked around with this message at 17:00 on Sep 18, 2021 |
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Sep 18, 2021 16:54
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The Eyes Have It posted:That's loving cool, thanks for sharing about it. I don't work with metal at all so this is like watching magic to be. thanks. and that's kinda funny, because (if i may get self-important for a minute:) if these experiments only do one useful thing for other people beyond entertain them, i've hoped it de-mystifies metalworking, and cuts down the resource barriers and learning curves that prevent the uninitiated from getting to the point where they can execute their ideas successfully and produce genuinely-useful metal parts n tools at will. learning how to design a good and effective cutting tool is hard enough, add somehow getting the machine shop access and workshop hours on top of that and most people will never be able to explore the extremely fun umbrella of metalworking trades unless they're willing to make it their career. if you can print resin parts to a good quality standard and are willing to drop maybe $150 on a bottle of fancy resin and some esoteric metal ingots from RotoMetals, you're 9/10ths of the way to casting the stuff i've been posting, in terms of both knowledge/skillset as well as physical resources. I plan on doing a proper write-up/presentation for the process some time soon, once I've got a more fleshed-out body of demo projects and have more interesting + useful applications to get people excited. focusing on tooling seems like the most pragmatic and valuable angle, especially for places like makerspaces like newfatmike said, where you can really unlock the potential it brings as an augmentation or supplement to people's existing 3d printing/shop setups- but there's all sorts of neat directions you can go with this.
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Sep 19, 2021 00:23
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