Adding Digital Readout To A Non-CNC Mill

In the quest to add a digital readout to his mill, [Yuriy] has done a lot of homework. He’s sourced a trio of very capable scales, researched what kind of hardware his DRO should be based on, and even built a very cool display using seven-segment LEDs. After nearly a year of work, [Yuriy] finally hit upon something that works well: an Arduino and an Android tablet, perfectly matched for one of the prettiest machine shop displays we’ve ever seen.

[Yuriy] based his build off a trio of digital scales he bought from Grizzly. These scales bolt on to the frame of his mill and send data to their own display. An Arduino was used to pull the data off these scales and sent via Bluetooth to a Nexus 7 Android tablet.

Considering a DRO solely based on an Arduino and a character LCD would look a little chintzy – and the fact Arduinos can’t do floating point arithmetic – we’re really impressed with [Yuriy]’s very elegant solution.

Thanks [Lee] for sending this one in.

28 thoughts on “Adding Digital Readout To A Non-CNC Mill

      1. Why, yes! Yes, I *did* read the original article. Nowhere does it say that Arduino can not do floating point math.

        Indeed the floating point stuff *is* done on the tablet, but that’s incidental.

        Once again HaD editors fail at reading comprehension.

        1. It may be a little late, but I would like to point out that an arduino can VERY easily do floating-point math fast enough for a DRO system. I have one set up right now using encoders that increment every 0.00039″, which the arduino then rounds, and converts into a set of characters before displaying on a tv through an NTSC signal.
          It’s able to keep up a good enough refresh rate for there to be no visable lag.

  1. Similar idea using old DOS laptops and cheap standard digital calipers can be found here.

    I did a bunch of work to make adapters from Cen-Tech (harbor freights brand) and Quadrature encoders to the Yadro hardware. Also have some Caliper to serial code available out there.

    Wish I had seen these calipers before I started would have been much easier to mount :)

  2. Using a high resolution display to show segments -why? Showing the inactive segments – why? Using light blue in slightly darker blue to further reduce contrast – why?

    I’d use a fixed width font with high contrast or different colors for the axes. Check out dark schemes for syntax highlighting or just the HaD color scheme.

    1. Inquiry,
      The color scheme is actually white on black. The picture was white-balanced for incandescent light, so the screen came out blue. (look at the screenshot in the latest post).
      As far as the other questions: I was just playing with the UI and it made sense to mimic the “traditional” look. It might change in the final version…

      Thank you

  3. Very cool design and concept. I would love to see the Android code and what protocol you used in the N7. The limited reading I have made on it shows limited BT protocol alternatives, but I am a newbie… Great project, congrats!!!!

  4. Genius using the Android tablet! I have seen PC clones used similarly for XY interferometry measurement on very expensive machinery.

    Google needs to create an industrial division, seriously.

    Consider how PC clones are pressed into use for industrial and commercial tasks because they are so cheap. One factory I worked in had every QC gauge connected to a PC clone, in turn all connected via Ethernet to a server (also a PC clone). A bar-code reader and data logging unit used to cost $4k, so people started using serial port readers and PC-like laptops that together cost $1.5k. Android tablets can be used for all of this, cheaper still.

  5. Android aint good for industrial applications, or at least not yet… PC clones are useful because everyone are familiar with the architecture and software. Android has great graphics which the factories dun really fancy so its not worth having to redesign a new system.

    As of now, there are already a few scada systems that can be run off android but it doesnt seems to be taking up

    1. Android is not realtime.

      But works great as an UI.

      Considering cheapest tablets can be had for $50 (probably $70 with decent IPS screen instead of crusty picture frame 800×480 TN cant-see-shit-at-an-angle kind)

    2. I remember the invasion of Windows95 on the plant floor replacing PLC’s and assembly language IBM clones. Judging by the scrap and downtime, it wasn’t read either. But it happened. Whatever the latest engineer is familiar with, that technology will happen.

    3. “Android … for industrial applications … at least not yet.” Give it three years.

      Purchase decision makers felt comfortable with PCs (even Ludites who did not use them but wanted a “justifiable” decision). The same is happening now, even more so, for tablets. People who will not touch a PC or Mac trust Kindles, iPads, etc.

      The factory I mentioned with a PC clone for each QC gauge had some stations with 3 and 4 side-by-side PCs (and keyboards and monitors), but management was more comfortable with that than using “non-standard” PCs with more than 2 serial ports or switch boxes to select amongst what was in use.

      PCs and, I predict, tablets are like duct-tape, cheap low-tech that works for almost everything.

      1. On a side effect, not many supplies want to provide open-sourced solutions, (its not like they can sell a system every other day) thus they definitely wants to lock their customers (apple?).

        Now everyone is just waiting for that “market spoiling” disruptive product and all hell will break loose.

        1. “Now everyone is just waiting for that “market spoiling” disruptive product and all hell will break loose.”

          It’s called LinuxCNC, formerly Enhanced Machine Controller 2 or EMC2. EMC2 was a project of the National Institute of Standards and Technology.

          It’s free software and there are many people working on and addting to and customizing it to handle anything required for CNC. LinuxCNC can do things the controls on the machines with 6 and 7 figure price tags can’t and it runs on a cheap PC.

          There are ports in the works to RasPi and the Beagle Bone Black, and similar little computers. The hurdle larger than the software for them is getting hardware designed and built for motor control. LinuxCNC doesn’t (yet) support USB or Ethernet connected motion controllers or breakout boards. When it does, then a BBB will become a very cheap CNC control system, no PC required.

          Mach3 is commercial CNC software for Windows. If the PCs parallel port performs well enough, it only needs a breakout board to connect up to stepper motor drivers. Alternatively it can use a separate motion controller via USB. Dunno if it can do control through Ethernet. Mach3 is mostly worked on by one guy and it’s nowhere near as versatile as LinuxCNC, but it’s easier for the CNC newb.

          The big players in industrial CNC aren’t acting too worried. Companies like HAAS and Fanuc push their service contracts and they do know their own systems inside and out, but proprietary commercial systems just aren’t as flexible as a generalist type computer running open software. When one of the big companies wraps up the open LinuxCNC inside a proprietary shell with hardware tie-in so they can get the bennies of the wide world of open source AND make big money… Same thing Apple did with BSD popped into a colorful candy shell they could sell.

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