CoreXY For A Dry Erase Plotter

After years of playing DnD, it’s finally [Mike]’s turn to be a DM. Of course he can’t draw maps with his hands, so that means building a tabletop plotter.

[Mike] is basing his tabletop game plotter on the Makelangelo, a polar plotter that draws images on a vertical platform with the help of two motors in the corner. This is a tabletop plotter, so the usual vertical arrangement wouldn’t work, but there are some projects out there that use the CoreXY system for a similar horizontal build.

The tabletop CoreXY system is built from rigid aluminum yard sticks, 3D printed parts, two very cheap stepper motors, an Arduino, and a whole lot of string. It’s a very inexpensive build and because [Mike] is using metal rulers for the frame, it’s also very low profile – a nice advantage for table top sessions.

So far, [Mike] has the axes of the plotter moving, with a servo and pen mechanism next on the build plan. He has a few neat ideas for how to plot these dungeon maps by vectoring bitmap images and sending them to the Arduino, something we’ll probably see in a an upcoming build log.

You can check out a video of [Mike]’s build below.

45 thoughts on “CoreXY For A Dry Erase Plotter

  1. Well, great. enough people have reported the top level comment in this comment thread that the threading has screwed up.

    Remember, the ‘report comment’ button is not an ‘I disagree’ button. However, due to overwhelming demand, I’m putting the comment in the trash, and moving this comment (the one you’re reading right now) up to the top. Good luck figuring out the threading here. Due to the way WordPress screws up comment threading, all the replies to the top level thread should be below this one.

    To answer the question, ‘why not update the post with this information’, I’m just going to glibly suggest that no one reads the articles. I will note that only three of the twenty five comments for this post are actually about the linked project. Keep it classy.

    Replies to this comment will be deleted.

    1. So this doesn’t relate to Mike’s build but the one with yellow corner brackets… note that the belts in the central gantry are not parallel. This will cause problems with the belt tension changing as the head moves in X (along the central gantry), which will cause annoying printing errors.

      CoreXY requires that where a section of belt changes length due to platform motion, that belt must be exactly parallel to the motion. For example, the belts can be at any old angle in the crossover area because those belts don’t change length, but pretty much all the others need to be properly parallel.

      1. I’d think the pulleys mounted atop each other on the moving axis would also cause issues… I ran into this with a similar design. The amount of torque caused by this sort of setup caused tremendous and directional drag in my system. I went through several iterations to reduce that, ultimately ending up with a design that had all the pulleys in a single plane except, as you said, where the pulleys weren’t associated with lateral motion. Drag went from almost stalling the motors due to torquing-motion along the gliders in certain directions, to the point where the axis was literally floating on the belts themselves. If not for external forces on the pen (and the fact that some gliders were structural), the glider-rods could’ve actually been removed from the system. I’m glad I went through those design-iterations with paper and legos rather than CAD and 3D prints ;)

    2. Dan! It’s been awhile but someone was asking questions about this build on my youtube channel and I pointed him to your site for the code. I just want to say thank you again. It has been a highlight of my accomplishments to have one of my projects posted on HAD and your efforts helped me make my project. Keep up the great work.

  2. I (among many many others) brought that up years ago. Standard writing practise (aka Technical Writing 101) states that the first time an abbreviation or acronym is used, it should follow this format:

    Dungeons and Dragons (DnD)
    Dungeon Master (DM)

    From that first use, it’s then acceptable to ONLY use the abbreviation/acronym.

    Of course you can just use the abbreviation/acronym, as long as your paper has a glossary.

    1. That would all be true for an academic paper. Comment boards are drastically less formal. Dungeons and Dragons has been around for over 30 years and is pretty commonly known of in the technical community which has a substantial overlap with the gamer community. It is usually worthwhile looking something up or simply, politely asking.

      1. This is a comment board, but the article above isn’t.

        It’s good journalistic and blogist practice as well to introduce acronyms so you don’t waste your readers’ time with having to google stuff that could be explained with the addition of a couple words, and avoid potential misunderstandings. It takes you less than a second to type those words, and saves hundreds of people the bother.

        It’s arrogant to assume that a hacker is someone who necessarily knows what Dungeons and Dragons is, and downright dickish to then tell them to Google it, because the whole issue is that they have to cut their trail of thought to jump to Wikipedia before continuing with the rest of the article, which is only three paragraphs long.

        It just show that the editors do not appreciate their readership.

        1. i think it’s a big jump to go from using an acronym or two that you have mistakenly assumed most people would know to assuming they don’t appreciate their readership.

          I also think that calling someone an arrogant clown isn’t the most productive way of providing criticism. If the writer of the article is to be blamed for not following perfect journalistic practices, the commenters are equally to blame for being rude, disrespectful assholes.
          .

      2. Of course you are right. But on the other hand, if the editors choose to use an informal style like this, it opens the door for lots of whining. Better to be safe, and preempt all of the mess by writing in a clearer way.

      1. So you’re saying you steal all your articles from Google?

        No?

        Then you, the writer, shouldn’t be so freaking lazy and actually write so that all your readers can understand what you’re trying to convey. And that includes many readers where English is not their first language, so the abbreviation or acronyms are NOT obvious and Googling them does not always clear up the mystery since there are several definitions for that abbreviation and without context, Google can’t help.

        Or perhaps your overlords don’t care about your non-domestic readers.

  3. Just to clear up any further confusion because this is an arrogant world–
    HaD- HackaDay
    R&B- rhythm and blues
    PBR- Pabst Blue Ribbon
    MSRP- manufacturer’s suggested retail price
    LOL- laugh out loud
    BOM- bill of materials
    USA- United States of America (that one gets confusing because they skipped the ‘o’)
    BnB- bed and breakfast
    MPH- miles per hour
    MPG- miles per gallon
    ID10T- the problem with your computer

  4. Is there any end to this unecessary whining? Stop actnig acting like babies!! These isn’t a writing journal or university course. Its a hacking blog for christ sake! Stop pretending you have perfect writing skills and realize that humans are humans and make mistakes. Further more, this is small operation in comparison to others, which no staff of proof readers (or fact checkers for that matter, some of you think they are supposed to remember every article ever posted and cross check it with every other article posted about it), and I’ve seen more blatant writing mistakes on sites iknow have a full staff (looking at you make).

    BTW, this IS a NERD site, as much as I hate to say it.. and ALL nerds know what DnD and DM mean. so give back your nerd card….

    1. It’s less about being formal, and more about the attitude of HaD editors, where they make crappy editorial decisions and then become argumentative against their readership over it.

      Like the stream-of-conciousness article earlier about rube-goldberg machines where you couldn’t really tell what the article was about.

    2. The issue is that quite often these short forms might be referring to very different things as diverted as the readers of this site. If you are on a specialized D&D site, then you can expect the comments are for D&D, but this site isn’t one.

      just a partial list from wiki for DM
      Computing and the Internet
      * Data mart, a specialized version of a data warehouse
      * Data mining, searching large volumes of data for patterns
      * Daily Motion, a video sharing website
      * Direct Message, a personal message used on Twitter
      * Dream Maker, an interpreted programming language

      Software:
      * Device Management, programs for automatically updating the software on mobile phone
      * Device-mapper, a component of the Linux kernel that supports logical volume management
      * Digital Mars, an American software company developing compilers
      * DM (computing), a window system for AEGIS OS on Apollo/Domain workstations

  5. http://en.wikipedia.org/wiki/Troll_%28Internet%29

    Comerades, what we all actually doing here is feeding the troll. Hackaday frontpage should have a notice for halfwits and trolls to stay out. Or a strongly filtered comment system. If you cant say anything about the hack STFU. I dont care about your opinions of this place – I can form mine and can keep it to myself. I am grateful for the interesting posts regardless of them being first ones or reposts from somewhere else, and I can tolerate the ones which aren’t interesting to me.
    Thank you all for your attention.

    1. > Or a strongly filtered comment system.

      Yeah, no. The second I start moderating comments calling me an idiot, I’m going to get more comments saying I’m a fascist that doesn’t care about the readers or free speech or about some imagined slight against someone I’ve never met. I’m not going down that road.

      My moderation policy is that you’re free to make a complete ass out of yourself, and those comments will be approved. Doxxing, absolute shit comments, and obviously illegal speech will of course be moderated, but I’m granting everyone here a large amount of leeway.

      Incidentally, I would encourage anyone to write a ‘hackaday comment scraper’ that compares all approved comments with ones that are edited or removed. I’d actually love that as evidence of how little we moderate. First person to build that gets a hackaday post, and I’m serious.

      With that said, most of the people ITT are freaking morons that are far too willing to concern troll, counter troll, and generally make the hackaday comments a steaming pile of shit.

      1. “With that said, most of the people ITT are freaking morons that are far too willing to concern troll, counter troll, and generally make the hackaday comments a steaming pile of shit.”

        And THIS is why Brian is my favorite here. :)

      2. I don’t know how many times I’ve accidentally reported a comment while scrolling down the screen using the touchscreen on my phone. Many times it just seems a strategic placement caused by where it falls on the screen.
        I would remove the report comment flag or add logic before setting the flag to add a comment on why it is being reported with the option to cancel.

  6. I like the simple, state-of-the-shelf approach of this plotter. I built the TSR Drawbot from Make magazine last year and I played around with the dry-erase marker idea. I found pens that are ‘wet-erase’ that work much better. They don’t smudge as easily but still clean up nicely with a damp rag. This would make incorporating miniatures on the map much easier and neater. The drawbot design uses a simple adhesive cable clip as a pen holder that works quite well.

  7. Pity about some of the crap posted above as it’s quite a nice project. I’ve designed and built a corexy based 3d printer using extruded aluminium and I’m a big fan of the corexy approach. Surprised he doesn’t have problems with torsion as the frame can’t be very rigid given the size, on the other hand it’s a very light load.

    I have some of those steppers, some spectra* sitting idle and some small relatives that like to draw so will have to keep an eye on developments – hopefully he can get the pen plotter working well.

    *spectra is a brand of braided fishing line. It doesn’t deform under tension so can be used to replace belts in certain machines.

  8. Nice project!
    I would like to make/see a version that is mounted under a clear, edge-lit table, and uses those liquid chalk markers that fluoresce under black-light. Erasing would be harder, but maybe you could make some kind of quick-change tool holder that can swap the marker for an eraser.

  9. instead of dry-erase it should be clear plexi and the pen/plotter should be inverted. The plotter could draw a mirror image from the bottom which would leave the top surface for players to write on and erase without mucking up the DnD map.

    This would also give the plotter a lower profile and lower the viewing angle. Maybe some fancy clips to release the plexi for cleaning… I’m thinking like the frames movie theaters use to hold posters.

    1. @phnx Thought of that except the more technology I try to bring into my games the more time I end up spending setting up the technology and not reading up on the next mission.

      Pushing that issue aside.. I have something else I’ve been thinking up that will look very awesome but I dare not share it or someone more brilliant will beat me to it.

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