New Pens For Old Plotters

March 23, 2024 by 17 Comments

Finding consumables is an ever-present problem facing anyone working with old computer hardware. Many of these devices ceased manufacture decades ago and what old stock remains is invariably degraded by time. [Retrohax] has encountered it with the pens for an Atari plotter, a machine that uses an ALPS mechanism that appears in more than one 1980s machine. The original pens had dried out beyond the ability to refill, so he takes us through the process of finding replacements.

Sadly there are no equivalent modern pens ripe for modification, so whatever replacement he used would have to involve a little lateral thinking. He thought salvation was at hand in the form of multicolor ballpoint refills of the type where the ink is in an easily cuttable plastic tube. [Retrohax] and was able to make a 3D-printed holder for a cut-down ballpoint refill. Sadly the pressure required for a good line from a ballpoint was much higher than the original pens, so he was back to square one. Then he happened upon gel pens and tried the same trick with a gel pen refill. This gave instant success and should provide a valid technique for more than just this ALPS mechanism.

If you haven’t got a classic plotter to hand, never fear. You can have a go at making your own.

Traffic Updates On The Seven Seas: Open Source Chart Plotter Using A Raspberry Pi

November 4, 2019 by 7 Comments

As the Raspberry Pi in its various forms continues to flow into the wild by the thousands, it’s interesting to see its user base expand outside beyond the hacker communities. One group of people who’ve also started taking a liking to it is sailing enthusiasts. [James Conger] is one such sailor, and he built his own AIS enabled chart plotter for a fraction of the price of comparable commercial units.

AIS transponders in the Mediterranean. VesselFinder

Automatic Identification System (AIS) is a GPS tracking system that uses transponders to transmit a ship’s position data to other ships or receiver stations in an area. This is used for collision avoidance and by authorities (and hobbyists) to keep an eye on shipping traffic, and allow for stricken vessels to be found easily. [James]’ DIY chart plotter overlays the received AIS data over marine charts on a nice big display. A Raspberry Pi 3B+, AIS Receiver Hat, USB GPS dongle and a makes up the core of the system. The entire setup cost about $350. The Pi runs OpenCPN, an open source chart plotter and navigation software package that [John] says is rivals most commercial software. As most Pi users will know the SD card is often a weak link, so it’s probably worth having a backup SD card with all the software already installed just in case it fails during a voyage.

We’ve seen AIS receiver stations built using the RTL-SDR, as well as a number of projects around the AIS equivalent in aviation, ADS-B. Check out [John]’s video after the break. Continue reading “Traffic Updates On The Seven Seas: Open Source Chart Plotter Using A Raspberry Pi” →

Brachiograph: A Simple And Cheap Pen-Plotter

October 30, 2019 by 7 Comments

The BrachiGraph project consists out of two parts, the hardware design for a servo-driven drawing arm (pen plotter) and software utilities (written in Python) that allow the drawing arm’s servos to be controlled in order to convert a bitmap image into a collection of lines that can be used to draw an image resembling the original, in a variety of styles. All of the software and designs needed to make your own version can be found on the Github page for the project.

docs/images/readme_combined_image.png

Considering an estimated €14 worth of materials for the project, the produced results are nothing short of amazing, even if the principles behind the project go back to the Ancient Greek , of course. The basic hardware is that of a pantograph, which provides the basic clues for how the servos on the plotter arm are being driven.

The main achievement here is definitely that of minimalism, with three dirt-cheap SG-90 microservos along with some bits of wood, a clothes-peg or equivalent, and of course a pen providing a functional plotter that anyone can assemble on a slow Sunday afternoon from random bits lying around the workshop.

 

Pen-Plotter Firmware Written Completely In Ada

June 9, 2016 by 43 Comments

[Fabian Chouteau] built a plotter out of CD-ROM parts. Yawn, you say? Besides being a beautiful physical build, this one has a twist. He wrote the software and firmware for the entire project himself, in Ada.

Ada is currently number two on our list of oddball programming languages that should be useful for embedded programming. It’s vaguely Pascal-y, but with some modern object-oriented twists. It was developed for safety-critical, real-time embedded systems (by the US Department of Defense), and is used in things like airplanes, rockets, and the French TGV trains. If that sounds like overkill for your projects, [Fabian]’s project shows that it’s still very tractable.

In his GitHub, he re-implements the GRBL G-code generator and then writes a GUI front-end for it. In his writeup, he mentions that the firmware and its simulator for the front-end use exactly the same code which is quite a nice trick, and guarantees no (firmware) surprises when moving from the modelled device to the real thing.

We looked quickly around for Ada resources and came up with: GNAT, the GNU Ada compiler, and its derivatives: GNAT for ARM (STM32-flavor), ARM-Ada (LPC21xx flavor), AVR-Ada, and MSP430-Ada.

Any of you out there use Ada in embedded work? We’d love to hear your thoughts.

Continue reading “Pen-Plotter Firmware Written Completely In Ada” →

A Compact SCARA Arm Plotter

March 14, 2024 by 4 Comments

If you’re unfamiliar with SCARA robots, the acronym stands for Selective Compliance Assembly Robot Arm. This refers to the fact that the arms are rigid in the Z axis but somewhat compliant in the X and Y axes, and that they’re often used for assembly tasks. In any case, you can spend a great deal of money equipping your factory with these robots, or you can build your own for the fun of it. If you’re not endowed with a seven-figure investment for opening a production plant, consider exploring [tuenhidiy’s] project instead.

The build enlists an Arduino Mega as the brains of the operation. It’s paired with a RAMPS controller for running a pair of NEMA 17 stepper motors that actually move the arm in the X-Y plane. Additionally, a tray eject mechanism from a CD/DVD drive is enlisted to act as the Z axis. The frame is assembled from PVC plumbing components and a small amount of aluminium T-slot profile.

The resulting arm isn’t fast in the video we see of the build, but it works as a basic plotter without too much complaint. The benefit of the Z-axis in this case is obvious, as it allows the pen to be lifted off the page where necessary.

We’ve seen plenty of good plotter designs around these parts before, too. Video after the break.

Continue reading “A Compact SCARA Arm Plotter” →

2D Plotter attachment for 3D printer.

Ender 3 Plotter Attachment For Printing Onto Cassettes

March 9, 2024 by 15 Comments

One way to look at FDM 3D printers is as machines that turn filament into three-dimensional objects, but at their core they are much more versatile than that. Since they can move just about any tool around in 3D space, you can also use them for plotter tasks, a fact that [Geoffrey Gao] made use of when he had to write labels for a stack of music tapes. The resulting FS-Plotter project is based around a Creality Ender 3 FDM printer. Standard g-code from PrusaSlicer is used to move a pen around, after the latter has been fitted into a (3D-printed) spring-loaded fixture.

The cassette tape is fitted into its own fixture that is attached to the printer bed to hold it in place, while the writing utensil can move in its spring-loaded fixture to account for some unevenness on the surface it’s writing on. In the linked GitHub project a PrusaSlicer profile is provided that can generate 2D plotter Gcode. Where [Geoffrey] says that this project is very useful to him as a musician is that it enables him to make small runs of tapes with professional printing, without running into extra expenses.

Beyond putting a writing utensil into the holder, it could also be used for light engraving and similar tasks, while still making it possible to switch between the FDM hotend and this plotter attachment as needed. For about $30 in parts, it doesn’t seem like a bad deal to get a small-ish plotter and maybe give that old Ender 3 a second life.

Need A Serial Data Plotter? Better Write Your Own

January 29, 2024 by 12 Comments

When you’re working with a development team, especially in a supporting capacity, you can often find yourself having to invent tools and support systems that are fairly involved, but don’t add to the system’s functionality. Still, without them, it’d be a dead duck. [Aidan Chandra] was clearly in a similar situation, working with a bunch of postgrads at Stanford, on an exoskeleton project, and needed an accurate data plotter to watch measurements in real-time.

This particular problem has been solved many times over, but [Aidan] laments that many solutions available seem to be too complex, hard to extend, or just have broken dependencies. This happens a lot, and it simply leads to yet another project to get going, before you can do the real work it supports. Based on Python and PyQT5, serial-plotter is a new beginning, with an emphasis on correct data acquisition and real-time data visualization with a little processing thrown in. Think, acquire data, show the raw values as well as the mean value, and RMS noise all on the same windows side-by-side, all of which is easily tweakable with a bit of programming using Numpy and Matplotlib.

One particularly important point to highlight is that of the handling of time-stamping. [Aidan] needed to ensure samples were logged together with a local MCU timestamp so that when displayed and possibly later post-processed, it was possible to accurately determine when a particular value or event occurred. With the amount of buffering, data loss and multiple-thread shenanigans, it is easy to forget that the data might get to the application in a non-deterministic way, and just relying on local CPU time is not so useful.

If you need to visualize data transported over the serial port, we have seen many projects to help. Like the highly configurable Serial Studio, for one. If your needs are a bit more complex, especially with multiple data transport methods, then a Supercon 2022 talk by [Alex Whittemore] might be a jolly good place to start.