[HN Gopher] Building a DIY Pen Plotter
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Building a DIY Pen Plotter
Author : tobr
Score : 78 points
Date : 2023-10-02 06:23 UTC (2 days ago)
(HTM) web link (szymonkaliski.com)
(TXT) w3m dump (szymonkaliski.com)
| crtified wrote:
| The only thing that moves more impressively fast than the dancing
| pens in a high-quality pen plotter, is the human supervisor of
| said plotter, when some rare physical fault occurs, and the
| mechanism starts turning your big sheet of expensive paper into a
| random 3D pretzel at the speed of light.
|
| It very rarely happened! and certainly, most modern equipment
| would have inbuilt fail-safes, but trust me, when it happened, it
| wasn't subtle!
|
| One of those trash-style TV shows, based around 'When Plotters Go
| Bad', would be - as they say - "quite the lol".
|
| Other humorous old-fashioned plotter errors included those times
| when human error led to half the plot being drawn directly onto
| the plotter's vacuum bed (e.g. sent Landscape data, while the
| paper was loaded Portrait). Of little consequence except shame,
| that one.
| batterylow wrote:
| Nice project! I was gifted a pen plotter [1] a while ago and have
| enjoyed it so far. I would love to build one that supports larger
| pieces.
|
| [1] https://shahinrostami.com/articles/my-pen-plotter-setup/
| thot_experiment wrote:
| That is one EXTREMELY overbuilt plotter, you love to see it.
| CobrastanJorji wrote:
| For a properly extremely overbuilt plotter, you could do what
| I've done: tape a pen to a 3D printer. It's a bit like building
| a back massager by putting a cell phone on vibrate and texting
| it continuously, but it's also a dang good plotter once you
| figure out a set of G-Code instructions that don't destroy the
| pen by accident.
|
| I've been thinking of taking advantage of the ability to raise
| the pen really high to do something crazy like use a quill and
| an inkwell, but I use a bed slinger printer, so figuring out an
| inkwell that doesn't splosh ink around everywhere or floats
| just over the bed is probably more work than the idea is worth.
| tomek_ycomb wrote:
| A sponge is the inkwell you want :) micro-baffles
| thot_experiment wrote:
| I have a custom built plotter that paints in watercolor, I
| don't have a lot of good media depicting it yet, but if
| you're local to the Bay Area I'll have a booth at Maker Faire
| showing it off!
| ignite2 wrote:
| I'll look for you!
| CobrastanJorji wrote:
| That is really, really cool! I'm not but I look forwards to
| hearing more about it in the future. Really curious about
| how you move the brush. Pointillism? Filling polygonal
| regions with lines? Some sort of interesting "imitate real
| brushwork" algorithm?
|
| Do you do color change by swishing the brush in water? Ooo,
| does it mix colors? Because that'd be super fun if probably
| impractical.
| sleepybrett wrote:
| Here is a simple commercial product (designed by EMS who
| also makes the axidraw plotter)
| https://watercolorbot.com/
| thot_experiment wrote:
| I take a bunch of different approaches so the short
| answer is "Yes" but I'll try get a little more in depth.
|
| I mostly use something akin to a "imitate real brushwork"
| algorithm, but it's more a "mess with the code until it
| looks right to me" algorithm.
|
| > Do you do color change by swishing the brush in water?
|
| Sort of, this aspect of definitely has some physical bugs
| (flooding my work area occasionally) but I am using an
| automated water pot that works using a pythagorean siphon
| and is controlled using the coolant flood commands in
| GRBL (used to cool bits when cutting with a CNC
| ordinarily)
|
| > Ooo, does it mix colors?
|
| This is what I'm currently working on, but it's very much
| a non-trivial thing to solve. Luckily you don't have to
| be precise to make good art, there's a lot of opportunity
| for happy accidents.
|
| self promo: While I haven't been very good at producing
| compelling media about my plotter, I do have a patreon
| where for $7/mo I mail you a postcard-sized plot every
| month demonstrating whatever thing I'm working on at the
| moment. https://www.patreon.com/thot_experiment
|
| here are a few examples of last month's plots, these are
| colored by hand https://thiic.cc/heavy/bb_plot.jpg
| https://thiic.cc/heavy/crank_plot.jpg
| https://thiic.cc/heavy/pedal_plot.jpg
|
| and here's a few that are pure robot
| https://thiic.cc/heavy/abstract_plot.jpg
| https://thiic.cc/heavy/other_plots.jpg
| CobrastanJorji wrote:
| Really cool! Thanks for sharing.
| rtkwe wrote:
| Very over built. A lot of the times you just see two beams that
| advance their respective axis because there's so little force
| applied by a pen.
| app4soft wrote:
| Hardened CNC frame template.[0]
|
| [0] https://github.com/JMG1/PlasticSliderCNC
| Animats wrote:
| More useful is one of his references on how to build a CNC
| router.[1] This one covers all the usual mistakes one can make
| building a CNC router. (He skips the real n00b mistake - trying
| to use a Dremel tool in a CNC router. That never works. Dremel
| tools slow down or stall under load, and the CNC controller
| doesn't detect that, so it keeps pushing a stalled tool around.)
|
| [1] https://mattferraro.dev/posts/cnc-router
| syntaxing wrote:
| To be fair, most hobby CNC tools were opened looped until more
| tools came out that were BLDC + zero cross detection for speed
| control. That being said, stalling your tool more or less means
| you're just blindly cutting a part. Calculating the correct
| feed rate is absolutely essential for any router/milling
| operation.
| dheera wrote:
| Instead of open loop calculations, why not just actually
| measure the current (or motor RPM) and do a feedback loop?
| dekhn wrote:
| that doesn't give you step-level accuracy.
|
| Some systems do this- for example Prusa MK3 and newer don't
| have physical endstops, instead they monitor current. And
| FluidNC supports this but clearly points out you shouldn't
| use it for step-level accuracy.
| syntaxing wrote:
| Mixture of motor technology, cost, and application. Take a
| dremel for instance, adding all these features cost money
| and most dremel users won't care for it. Also certain motor
| technology makes it impossible to control in a meaningful
| fashion. If you stuck an encoder on a dremel, you'll still
| have a lot difficulty maintaining the set RPM.
| dekhn wrote:
| A few comments for those who want to go down this route: 1) you
| probably should buy a machine, rather than designing and
| building one, if your goal is to use the CNC. It will be
| cheaper and more of your time will be spent CNCing instead of
| rediscovering the painful lessons learned over the past
| decades.
|
| 2) he says woodworking equipment is only good for wood, but it
| also works for aluminum
|
| 3) ignore all the talk about grbl on arduino due or mega, use
| FluidNC on ESP32.
|
| 4) a dewalt 611 will work better than any spindle that costs
| less than it, and also many spindles that cost more, if you're
| working in just wood. This is a controversial opinion, if a
| spindle makes you happy, go for it.
| itronitron wrote:
| Yes, don't build your own CNC or plotter (from scratch).
| OpenBuilds has a good range of options and also a fairly
| active community of people adapting their platform for custom
| uses.
| ignite2 wrote:
| If you want the simplest plotter you can make:
| https://www.brachiograph.art/en/latest/
| Lalabadie wrote:
| The Makelangelo is also charmingly simple:
| http://www.makelangelo.com/
| wdfx wrote:
| That's really cool. I have a few of those servos laying around
| waiting for a project :)
| okamiueru wrote:
| It makes me so happy to read summaries of project like this.
| Thanks for sharing! I did almost the exact exercise a couple of
| years ago, except hand soldering the controller board together
| with an ESP32. It was an Core XY design with timing belts, also
| completely over-engineered. It suffered from hysteresis from too
| many plastic 3d printed parts (I only had belts, steppers, linear
| rails, and ball bearings). Would love to do it again some day,
| but properly. Definitely going for a pre-built CNC controller
| board, as that was a pain. Perhaps a Mach3 or Mach4 board
| Probably just make a PCB version, unless anyone know of a general
| ESP32 based 3-axis GRBL board with SD card?
| dekhn wrote:
| FluidNC on a Bart Dring board:
| https://www.tindie.com/products/33366583/6-pack-universal-cn...
| I used this with external stepper drivers to power NEMA23 axes.
| wdfx wrote:
| Grbl on esp seems to be not really a thing. You can however go
| the Arduino nano and el-cheapo CNC board + drivers for less
| than $20 or so. You can usually also plug in an Hc-05/hc-06
| Bluetooth module if you want it wireless.
|
| Beware that some of the cheapest CNC boards may have some dodgy
| wiring on the MS lines
| https://youtu.be/U839EbPw-A8?si=0SvVgZL0tX3j4P4K
|
| I've just completed a project using these parts
| https://doug.lon.dev/2023/09/19/astro-camera-mount.html
| [deleted]
| hugs wrote:
| "Grbl on esp seems to be not really a thing."
|
| Grbl on ESP32 absolutely is a thing. I've been using it to
| drive my robots for years. https://github.com/bdring/FluidNC
| Torkel wrote:
| Post about pen plotter without video. Hmm, I feel cheated.
|
| Random video of old school pen plotter in action:
| https://www.youtube.com/watch?v=3Cd3GsZlOBg
|
| My father still fondly talks about how the crispness of a true
| pen plot was never really matched by modern printers.
|
| Edit: he has them on a second page:
| https://szymonkaliski.com/projects/diy-pen-plotter Not as fast as
| the 1983 version though :)
| [deleted]
| CobrastanJorji wrote:
| They make a weird kids STEM toy that's a surprisingly well
| thought out pen plotter:
| https://www.youtube.com/watch?v=kSFW5ok3ROc&start=128
|
| The big arms are attached to the egg thing with two magnets, so
| a kid shoving their hand into the moving parts is very safe; it
| just falls apart. And you can see the clever arrangement of the
| three moving parts (axis 1, axis 2, and lift/drop pen).
| blacksmith_tb wrote:
| I have a Watercolorbot[1] which is like the world's most
| inexact plotter. But it's a lot of fun to watch it pick up
| paint on the brush and try to paint a gcode version of your
| design (also funny to see the patterns the slicer algo uses
| to try and fill blocks of color). Software was always a
| little fiddly, but still a fun idea.
|
| 1: https://watercolorbot.com/
| deepspace wrote:
| > crispness of a true pen plot was never really matched by
| modern printers
|
| I don't know about that. Pen plots can, at a push, achieve the
| equivalent of about 250dpi.
|
| Back in the early 90s, I wrote software for the first inkjet
| "plotter" (a wide format printer that used HP inkjet
| cartridges, and rasterized HP-GL commands on the fly). Even
| back then, we could get 600dpi resolution, and today's printers
| can do up to 2400 dpi.
| mkl wrote:
| My mid-1990s Graphtec plotter has a precision of .01mm, or
| 2540dpi. I don't have any pens for it fine enough for that to
| matter though, and have yet to build a generic pen-holder (it
| grabs the pen with magnets...).
| deepspace wrote:
| > I don't have any pens for it fine enough for that to
| matter though
|
| Yes, that is the issue. The finest pen you could likely get
| would be 0.1mm (and even that would be hard to find and
| expensive). That is what I based the 250 dpi on.
| dekhn wrote:
| The point is generally no matter how high your DPI, if you're
| drawing a line using a series of points, compared to drawing
| a line via a vector process, the vector process will almost
| always look nicer (for some definition of nicer).
| Torkel wrote:
| Yeah... but I think what he misses is that it's a line drawn
| by a pen. It has a certain analog appeal to it?
|
| Vinyl is worse in every way to lossless digital. As is an
| analog film camera. Or a mechanical watch for keeping time.
| Still though.
| zellyn wrote:
| What is the final resulting accuracy?
| buildsjets wrote:
| For a history of some of the earliest CAD/CAM and plotters, ref.
| "A Possible First Use of CAM/CAD" by Norman Sanders, Chapter 4.
| https://inria.hal.science/hal-01526813/document
|
| The gist of the paper is that computer aided manufacturing was
| developed FIRST, and computer aided design was an offshoot of
| that. When they had developed their prototype CAD system, the
| available pen plotters could not output drawings in a high enough
| resolution to be used for downstream manufacturing processes.
|
| "In short, at that time computers could master-mind the cutting
| of metal with great accuracy using three-dimensional milling
| machines. Ironically, however, they could not draw lines on paper
| accurately enough for design purposes; they could do the tough
| job but not the easy one.
|
| However, one day there came a blinding light from heaven. If you
| can cut in three dimensions, you can certainly scratch in two.
| Don't do it on paper; do it on aluminium. It had the simplicity
| of the paper clip! Why hadn't we thought of that before? We
| simply replaced the cutter head of the milling machine with a
| tiny diamond scribe (a sort of diamond pen) and drew lines on
| sheets of aluminium. Hey presto! The computer had drawn the
| world's first accurate lines. This was done in 1961."
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