As I mentioned in the last post, the new version of the Android DRO application has a lot of updates. In addition to the new functions there is a plethora of internal changes. Some of the new features are accessible through the “Settings” screen. The good news is that if you intend to use the application with one of the iGaging controllers, the default settings will be sufficient to make it usable out of the box. On the other hand, to take advantage of the new features, you will need to get your hands dirty. In this post I will try to explain what each of the settings does, hopefully making the setup pain-free.
This category currently has a single setting: “Readout Display Format” that let’s you choose how many digits the main DRO screen displays per axis. The purpose of this feature is to save some screen real estate on smaller devices. I.e. if your mill has less than 10 inches of travel in each direction there is no reason to show two significant digits; similarly, you might not want to see the ten thousandths.
|Readout display format can be set to match the travel and encoder resolution|
NOTE: This feature is still in “Beta” state. Unless you gave a compelling reason to use USB, I strongly recommend that you stick with BlueTooth.
|USB connection can be enabled with the "USE USB Connection" checkbox|
USB connectivity has been one of the most frequently requested features that is included in the new version. To switch from Bluetooth to USB you will need to check the “USE Usb Connection”, set the BAUD rate to match your controller and restart the application.
|USB transfer rate needs to match the controller|
When the app is in USB mode the “Connect” button doesn’t bring up a “Select Device” dialog. Instead you will see a system confirmation box requesting a permission to use USB. If you grant the permission the DRO will connect to the controller.
Side Note: There appear to be two reasons people ask for USB connectivity: some inexpensive tablets don’t have Bluetooth support and some people don’t trust the wireless connection. If you’re in the second group, I recommend that you stick with BlueTooth, since in practice it’s no more error-prone than USB and in a noisy garage can in fact be less sensitive to interferences. Remember, this is the same Bluetooth you likely use in much noisier environments, such as in your car, etc.
X, Y and Z Axis Settings
Settings for the first three axes use the same pattern, so I’m lumping the descriptions together. W axis behaves differently, so it will be covered in a separate section.
|Axis preferences are similar for the X, Y and Z axes|
|"Axis Label" setting can make the DRO display reflect the machine setup|
By default the first three axes are marked X, Y and Z. This makes sense in a DRO for a milling machine but people using the app with a lathe might want to make the display match their machine. By changing this setting you can set the labels that appear next to the readout on the main screen.
|Axis label can be set to any arbitrary text|
Digital scales, calipers, rotary encoders etc. work by counting clicks (pulses) that need to be translated to distance in inches, millimeters, palms etc.”Axis CPI” (Axis Clicks Per Inch) setting lets the application know what the resolution of your scales is, so the DRO can display the correct readout.
|Axis CPI is used to convert raw output to inches|
Tip 1: Lathe users will notice that with default CPI the cross slide scale measures radius. In other words, when you moved the cross slide 0.001”, the lathe removes 0.002” of material (one thousandth on each side). The DRO can easily compensate for this by setting the CPI to 2x the actual value, i.e. 5,120 rather than 2560.
Tip 2: All iGaing AccuRemote and DigiMag scales use 2,560 CPI and the standard chinese scales use 20,480. On the other hand, if you don’t know the resolution of your scales, it’s easy to find out once the scales are mounted on the machine: set the CPI to 1000, zero out the display and move the axis exactly one inch using the graduated dials or a dial indicator. Now take the reading you get and enter it as the CPI for that axis (ignoring the period).
Depending how you mounted your scales they might read right-to-left or left-to-right. The DRO uses the “right hand” rule for the position as shown in the diagram below and having the scales reversed will make things pretty confusing. Using the “Axis Invert” setting you can reverse the direction so the DRO reads the positions with the right polarity.
W Axis Settings
|W Axis settings are different from the other three axes|
The fourth “axis” is handled different from the other three since it’s readout is not displayed directly. Instead it can be added to one of the other three axes. This feature might be useful for people that will use this DRO on a milling machine that has two movements on the Z axis, such as Bridgeport (and clones), RF-45, Sieg X3 and similar machines. In such case the knee or the head scale can be assigned to the Z axis and the quill can be connected to the W axis. The DRO will add the positions up and display a combined readout.
W Axis Enable
This settings does just that: enables the W axis so the application starts paying attention to it.
W Axis Target
As I mentioned above, W axis is not displayed by itself. Using the “W Axis Target” setting you can choose which axis will be summed with it.
|Use W Axis Target dialog to combine two axes into one readout|
Axis CPI and Axis Invert settings behave identically to those of the X,Y, and Z axes, so I won’t repeat myself here.
A lot of changes that I’ve made to the application were designed to make it more flexible and lay groundwork for future expansions. On the other hand they add complexity to the application. I hope that this post will clarify what the purpose of each setting is and how it can be used. If you find the new additions useful or can think of other features you’d want to see in the coming version, please leave a comment or send me an email.