[HN Gopher] How to make (almost) anything (2020)
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How to make (almost) anything (2020)
Author : akeck
Score : 172 points
Date : 2022-03-07 15:45 UTC (7 hours ago)
(HTM) web link (fab.cba.mit.edu)
(TXT) w3m dump (fab.cba.mit.edu)
| DoingIsLearning wrote:
| All the videos linked in the class show me a message "video is
| not rated", saying I am unable to watch?
| ksdnjweusdnkl21 wrote:
| I wonder how one should host their educational videos to have
| them be available without ads or other nonsense like this. Any
| affordable solutions?
| lupire wrote:
| What do you mean?
| DoingIsLearning wrote:
| As in the video is not porn/violence rated and I am too
| anonymous for Vimeo to know if I am an inocent unsupervised
| child on the internet.
| nomemory wrote:
| If i am allowed to joke, I was expecting to read an article on
| Rust.
| bogwog wrote:
| I think you misread the title as "how to remake (almost)
| anything"
| chasd00 wrote:
| Next weekend can't come soon enough :)
|
| I'm in the high power rocketry hobby and got a Prusa i3 mk3 for
| myself for Christmas. It's pretty amazing to sketch a bit while
| on conference calls, then after work model my sketch in
| Fusion360, export the mesh, import to Prusa slicr, export gcode
| to an sdcard, start the printer and goto bed. Next morning,
| there's my part waiting for me.
|
| Electronics is the next bridge to cross and i really hope this
| class helps with that. I know a guy in the hobby who went from
| nothing to selling a custom designed altimeter for rockets on his
| website in about 6 months which was pretty impressive to me.
| https://flightsketch.com/store/catalog/flightsketch-mini_1/
| andi999 wrote:
| What annoyed me was that the slicer does not mantain hole
| diameters, somehow holes are smaller. In my case I was planning
| to prototype cnc milled stuff (which is kind of expensive), but
| this killed to use case.
| joshvm wrote:
| This is, I think, partly due to how the slicer routes the
| filament paths. I've had this problem moving between nozzle
| diameters and the only reason I could think of was that it
| wasn't possible for the slicer to maintain both accurate hole
| diameters and the correct placement of filament relative to
| previous extrusions. The STL was identical, but the parts
| printed with a 0.8 mm nozzle were undersized and _only_ the
| holes. My experience of this was with Cura and an Ultimaker
| S5. Generally you should always start printing loose holes
| and tightening them up as you go to see where the limit is.
|
| The simplest dimension to control is the perimeter. That can,
| for most parts, be perfectly accurate because there are no
| constraints on where the nozzle needs to avoid. However if
| you print a hole close to the edge of a part then the printer
| somehow has to lay down both an accurate edge to the hole
| while maintaining suitable separation from previously printed
| stuff. Essentially your design is quantised by the nozzle
| diameter within the perimeter of the part (I may be wrong
| here, but this seems like a simple explanation). You may have
| better results if you tune your part to the printer/nozzle
| you're using so that the slicer doesn't have to worry about
| leaving/filling gaps that are non-integer multiples of the
| nozzle size. In theory this shouldn't matter, because the
| hole perimeter can also be printed first, as it's an
| "outside" edge, but it doesn't always seem to work that way.
| chasd00 wrote:
| i've noticed things shrink a bit when the cool off ( at least
| with PLA ). What i do is print, test fit, adjust dimensions,
| then print again. It usually only takes one or two iterations
| to get it just right. I built a deck once, designed it,
| spec'd out all the materials i would need, optimized for
| minimal wastage, the whole 9 yards. I learned the hard way
| that in the real world dimensions are a matter of degree and
| what's on the label may or may not be what you get (to a
| ridiculous degree when it comes to lumber).
|
| I'm use to software where it either compiles or it doesn't,
| it either works or it doesn't. In the real world with
| physical objects it's much more a matter of "is it close
| enough or not".
| dekhn wrote:
| Holes with interior dimensions close to the width of the
| nozzle are hard and need to be calibrated if you absolutely
| need to print them to size. Basically, the plastic is
| "spreading" a bit wider than the nozzle tip.
|
| better solutions, rather than making exactly sized holes, is
| to increase the number of vertical walls, make the hole size
| slightly under, and use a precision drill and reamer to get
| to the target size. Also, make sure you're setting your
| scaling right (for example, I need to set my object size to
| be 100.6% of its designed size, because PLA shrinks when it
| cools).
| maxioatic wrote:
| Yeah this is just a thing you have to design around while
| using FDM printers, as others have mentioned. I really like
| melting in threaded inserts if you need threads, otherwise
| use a drill bit or reamer. If you need super tight tolerances
| (like CNC level tight) then a consumer grade 3D printer
| likely won't get you there though.
| 2muchcoffeeman wrote:
| Prusa uses 3D printed parts and I'm a bit surprised just
| how good the prints are.
| LeifCarrotson wrote:
| The slicer does maintain hole diameters, but just like CNC
| milling HDPE, you should expect dimensions to change a little
| after printing. If you need to have a tight tolerance fit on
| something, expect to run a drill or chucking reamer through
| it after printing. If it's really tight tolerances, it's easy
| enough to melt or press a drill bushing or threaded insert
| into an oversized hole to get fits tighter than you're likely
| able to hit with a mill.
|
| Your expensive parts likely go through many steps before and
| after manufacturing already that involve things like
| fixturing the material in place, rotating it and reacquiring
| datums, running taps through by hand, deburring sharp edges,
| etc; you should not expect 3D printing to be as easy as
| sending the STEP file to the machine and getting a complete
| part out. Sanding, acetone vapor polish, drilling, reaming,
| tapping, etc. are normal parts of the manufacturing and
| prototyping process.
| theelous3 wrote:
| Just an fyi drills are not good for tight tolerances. They
| cut trilobular holes, not circles.
|
| Reaming or boring are the route to tight tolerances.
| andi999 wrote:
| Which slicer do you use? It seems to be a known problem of
| cura.
| sokoloff wrote:
| I use Cura. It's across FDM printing techniques and is
| (somewhat) akin to the errors in subtractive
| manufacturing. Subtractive errors/inaccuracies tend to be
| of the type that remove too much material. Additive
| errors/inaccuracies tend to add material.
|
| My models for FDM often include a "hole size
| compensation" user parameter and I tweak it to introduce
| an offsetting bias in through-holes. (Non through holes
| tend to get heat-set brass inserts, which are more
| forgiving of the 0.1mm or less radial errors.)
| 2muchcoffeeman wrote:
| You can print a clearance tolerance test to see how
| accurate your printer is. I use a Prusa mk3s and as
| accurate as it is, at best my tolerance is 0.1mm. Enough
| to stop your parts fitting together. I normally build in
| a 0.2mm tolerance for close fitting parts.
| 0_____0 wrote:
| IIRC there's a param in the slicers I've used that can fine
| tune hole sizes.
| roland35 wrote:
| Next thing you should do is get a raspberry pi with octoprint!
| Then you can drop the gcode in from your web browser :)
| sanj wrote:
| Gershenfeld helped coordinate a bunch of folks with COVID work
| too!
| gabrielsroka wrote:
| Here's a complete class listing
|
| https://cba.mit.edu/classes
| Metacelsus wrote:
| See also "How to grow (almost) anything":
| https://fab.cba.mit.edu/classes/S63.21/
| forgotmyoldacc wrote:
| Note that the title is fairly misleading, students don't
| actually do real practical labs. A random example: https://fab.
| cba.mit.edu/classes/S63.21/class_site/pages/micr.... Probably
| because this class was being held during COVID times.
|
| There's no hands on biology work. Homework consists of:
|
| - Find a research or journal article - Propose a technology -
| Propose a methodology
|
| etc
|
| The 2019 version looks a little better:
| http://fab.cba.mit.edu/classes/S66.19/S66.19/
| azinman2 wrote:
| I never took this back when I was at the Media Lab and that's one
| of my main regrets from that time. This class is very famous, but
| I'm not sure how useful this is as an online class because as a
| normal person you won't have access to the water jet cutters,
| plastic mould injection machines, etc.
|
| Covid aside, hacker spaces were already dying out in SF. I wish
| there was more push for ordinary people to become makers rather
| than just consumers.
| chasd00 wrote:
| 3dprinters are pretty accessible but you're right about other
| tools. Also, some of the tools can be pretty dangerous (
| looking at you lathes/mills ).
|
| IMO one of the greatest things about software development is
| you can goto walmart and get $500 laptop, sit in a coffee shop,
| and have access to all the tools needed to build cutting edge
| high performance software of any type. It's not so easy to do
| that in meatspace with physical objects.
| adamsmith143 wrote:
| As someone not much into this scene, how useful are 3D
| Printers actually? I get the sense that they're very useful
| to hobbyists or for creating prototypes but are the plastics
| used suitable for production use cases?
| theelous3 wrote:
| Without going in to it - there is a massive range of
| plastics and non plastics of varying quality, expense, and
| accessibility.
|
| Yes, 3d printing is a legit method for production.
| _Typically_ if you can have a die made for it you will be
| better off in the long run with casting. Dies are
| incredibly expensive however.
|
| Smaller runs or highly specialised and difficult geometries
| benefit from 3d printing.
| akamoonknight wrote:
| I think to some extent it's a frame of mind thing. For
| instance, my friend's vacuum broke for some reason or
| another, some plastic piece that wasn't super complicated,
| but was required for functionality. And rather than buying
| a new one, he was able to model and print the piece that
| broke and the vacuum is able to work again, but mileage in
| general probably varies.
| srcreigh wrote:
| except for video games and deep learning
| baud147258 wrote:
| depends on the video game. If you target what AAA was doing
| 5 or 10 years ago in term of graphical quality or even
| specific style like low polygon, pixel art, 2d art..., you
| don't really need the cutting edge in terms of graphic
| cards.
| dannyobrien wrote:
| Noisebridge is re-booting pretty successfully in San Francisco
| -- a break during early Covid was either well-timed or
| overdetermined, because they also had to move venue due to rent
| rises, but the new space is coming together, and there's a
| bunch of in-person events now kicking off to celebrate the
| space's fourteenth birthday:
|
| https://www.noisebridge.net/wiki/Noisebridge
| azinman2 wrote:
| Happy to see they're back! The death of maker spaces in SF
| has been very sad for me.
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