It's been a year since I released the last version of TouchDRO, and it's definitely time for some updates. If you've been following this blog, you might recall that I made "Beta" version available at the end of last year, and was planning to push a new version out around February of this year. Well, it's the end of October, but finally I got it stable enough that I feel pretty good about letting it into the wild. There is a ton of changes, including many new features that people have requested. I will try to cover the important ones in this post, and over the next couple of weeks (as the time allows) will dig deeper into some of them.
One of the new features in the upcoming version of TouchDRO app is tachometer readout. The beta version of the application had full tachometer support for some time now. Over the last few weeks I added directional tachometer support to all four controllers. In this post I will try to give you some ideas on how to build a tachometer for your mill or lathe using commonly available parts. Your setup will vary, of course, but the main principle will be the same, so you shouldn't have too much trouble to adapt these designs to your particular needs.
Since I added a DRO to my mill I can't imagine how I lived without one for so long; it makes working on the mill so much easier and more efficie. Since you're reading this post, you are probably looking into building a DRO as well, and if you feel lost, you're not alone. Although I've been trying hard to keep the project as simple as possible, so it remain accessible to people with little or no experience with electronics or computers, it might seem a bit overwhelming.I this post I will provide a quick summary of the steps needed to get a DRO up and running with links to more information where appropriate.
TouchDRO is designed to work with a wide range of scales and machines, but it will not work right out of the box. After the application is installed, it needs to configured to match your particular setup. The process isn’t complicated and takes just a few minutes, though.
By default the application is configured for a three-axis vertical milling machine that uses imperial units. If that matches your setup, the only thing you’ll need to do is to configure your scales and the DRO will be good to go. Otherwise, there are a few additional settings that needs to be changed.
I’ve received a fair number of complaints about the readout being inaccurate when the default counts-per-inch were used. These problem can be caused by several different issues. First of all, CPI for most of the the capacitive scales isn’t officially provided by the scale manufacturers. The values for many of the commonly available scales have been found experimentally, and might be off by one or two counts. In addition, there are manufacturing tolerances, rounding issues etc, that can skew the numbers even more. Furthermore, many of the scales that come from China are metric. For instance, the glass scales that are advertised to have resolution of 0.0002” have resolution of 0.005mm, and 5 microns don’t equal 2 ten thousands. This leads to an error in CPI. Based on the 0.0002” resolution the CPI should be 5000, but in fact it’s 5080, which is almost 2% off.