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Starting a 3D printing index thread. 1. First serious experiment, which went wrong...
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Printing my first self-designed part 😬 Did it with OnShspe+Cura... haven’t used CAD software since 1996, which was ancient version of ProEngineer. Things have really advanced a lot. Browser+cloud-basedwith version control and all sorts of other crap.
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Sticky print folklore
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3d printing is a world of superstition and old wives' tales. Tricks I read/was recommended for getting stuck-on prints off the build plate: 1. Wait for it to cool so differential contraction breaks the bond 2. Take it off hot (while it's still soft at the bottom?) 3. Ice it... twitter.com/vgr/status/129…
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First success thread
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Success! 3d printed the lost telescope cap cover! With vanity logo too 😎 The tolerance is a little off, so it’s not quite a snug interference fit. Wondering whether to reprint or use this with a bit of tape or something to line it for a snug fit.
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Round 2: doorstop and whiteboard clamp
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3d printing adventures volume 2. Part 1: door stop. Random model I downloaded was too big for my printer, so I shrank it without measuring. Shrank too much, so had to design and print a little pad to glue on. Well it works.
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Printing a roller for wife’s pottery experiments. Also just designed a stamp based on a photo she found, queued up to print next. Learned a few new OnShape tricks doing that. This is the most CAD I’ve done in 25 years.
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Gear design and printing accomplished! Sub-thread on further adventures there. Been a while since I updated this thread so you'll notice my newer prints are red rather than black. Bought the red filament to print stuff for my rover and is now default.
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Figured out how to make gears in OnShape today using their featurescript. I am now officially unstoppable. 3d printing them now. This is just a hacky test job (those spokes on the largest gear are bad... I made them with a pattern of holes rather than an equal width spoke)
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Nope. Support adhesion failed near end of print. I think I need a raft for this. And/or design in my own supports. The two pillars at horn tips got ripped up. Wonder why? Up-tension from horn curve?
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Recently remembered one of my earliest introductions to engineering thinking: my dad (a mechanical engineer) posing a classic CAD brainteaser to me when I was a teenager: what object looks like a circle in the top view, a triangle in the front view, and a square in the side view?
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Later in freshman engineering school, our engineering drawing instructor posed the same brainteaser, before proceeding to demonstrate the answer by shaping a piece of chalk into the answer (whittling a piece of chalk by rubbing it on a board is legit machining btw)
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The answer, which I just made in OnShape using the loft feature, is a thing which may have a name, I don't know, but is kinda like an oddly shaped cone frustum. Here is the drawing:
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Ignore weird lines. They are an artifact of how OnShape does lofts geometrically. A loft is when you smoothly transform one face of an object into another. In this case, the 2nd surface should actually be a 1-d edge, but OnShape needs a face, so I made a very narrow rectangle.
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Another way to pose the brainteaser is to ask: what object can plug a square, circular, or triangular hole, depending on how you orient it? So just for fun, I made a stencil of that too.
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I actually don't know if this is the "only" correct answer. Afaict, a 3-projection view completely determines a solid model, but maybe complex surfaces have indeterminacy. I think I'll have to sand off some edges to make it the right answer.
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Doh. Of course the solution is not unique. This one is skew symmetric. Any set of contours that fits within the 3 contours will do. I could have added a halfway loft plane with an ellipse cross section and that would have forced symmetry.
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Anything contour that stays within the bounding box defined by square and triangle projection lines will work. Blue is what OnShape generated. Red is what I’d force if I wanted.
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Also reprinting the horns from yesterday. Scaled down 50% with raft. Dunno what all that wispy stray fiber is. Too dry? From supports being printed coarse? PLA spool being not as good? Drip during travel?
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Done. Messed up a bit tried to make the triangle equilateral and the rectangle a square at the same time. Doh. No way to satisfy this template. If you have a square, triangle will be isosceles.
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Fingers crossed. Seems to be printing fine. Shiny with some stringing. Used Cura generic presets for TPU-95, whatever that is. Higher nozzle temperature (228F) but lower bed temperature (45) than PLA (205/65)
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ugh broke thread... continues here
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Decent compliance, rather stiff at normal resolution printing with 60% infill. I bet I could get much wider range by messing with infill density. But clearly settings need work. But unlike PETG this feels different enough as a material, it’s worth mastering.
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