More New Features in TouchDRO

Thursday, February 6, 2014

About a week ago I started posting nightly builds of the new release of TouchDRO application. Based on the feedback provided by the beta-testers I've made a few changes to the user interface. The biggest one is the addition of the new "Axis Details" screen. It's purpose is to display the feed rate and chip load while the axis is moving, and offer few axis-specific functions.

Clicking the axis readout brings up the "Axis Details" view

Feed Rate Display

Feed rate is the linear speed at which the workpiece is moving past the cutter. Based on the currently selected units this readout will display the feed rate either in inches per minute or millimeters per minute. The value is refreshed roughly twice per second.

Chip Load

Chip load is the rate at which the metal is being removed. It can be thought of as the thickness of the chip being removed by each flute. Correct chip load is critical to tool life and surface finish. For instance, when it's too small the tool will rub and will wear prematurely. On the other hand, if the chip is too thick the flutes will load up and the tool can break. In fact, one of the most common reasons for breaking small end mills is too high of a chip load.

The formula for chip load is Chip Load = Feed Rate / (RPM * Number of Cutting Teeth). This means that, in addition to the feed rate, the DRO needs to know the tooth count of the selected tool and current RPM. Tooth count is set by selecting a tool from the tools list. When you click a tool, "Set Offset" dialog will pop-up. If no offset is desired, "X Offset" and "Y Offset" can be left as "None". RPM is provided by the tachometer.

Axis Functions

The "½" (A.K.A. "Centerline"), +/- and "Set Zero" functions are not new. The latter is a bit redundant, since the same effect can be achieved by long-pressing the "abs/incr" button next to the axis. I added it because it might be useful while finding the center. For example, you would start by indicating one side of the hole, set axis to zero, indicate the other side and click "½" to find the center. A notable new addition is the "Audible Alert" function. When activated, the DRO will beep with increasing frequency as the spindle/tool approaches zero, starting at 0.250"/10mm away from it.

Preset Dimension

Long-pressing axis readout brings up the new "Set Dimension" dialog

Although this is not a part of the Axis Details dialog, this function is closely related to it. It can be activated by either long-pressing axis readout in the main screen or touching the position readout in the "Axis Details" screen. There is one notable change in the function compared to the previous version: it now gives you an option to preset absolute dimension. This might be useful in a situation where a drawing's dimensions reference a point that can't be indicated on the mill. In such case you can locate a feature whose coordinate is given in relation to the drawing's reference point and preset the axis to that dimension. From that point on all other dimensions will be in relation to the drawing's origin. Finally, although I like math, I still can't convert things line 17/32" to decimal in my head quickly. To make the life a bit easier for other folks that deal with fractional dimension, the dimension can be entered as a decimal number or as a fraction.

Minor Changes

In addition to the features described above, I've made a few minor changes to the UI to make the app a bit more convenient to use. First of all, if the app was connected when you exit it, it will try to reconnect to the same device automatically. Second, when a tool is selected, it appears green in the tools list. Finally, tachometer value can be preset manually. If your mill uses a set of step pulleys to change the spindle speed, you will be able to preset the RPM to the current speed so it can be used by the "Chip Load" function.

Selected tool is shown in green
If there is no tachometer, RPM can be set manually

Finally, special thanks to the people who took their time to provide feedback on the beta version. Your input is very valuable and greatly appreciated. Keep it coming and I will try to keep up.


  1. Yes! I'm so happy the feed rate and audible warning made it in! That's going to be really handy.

    1. I'm most likely an idiot, but in using TouchDRO downloaded from the Google Play Store, and I cannot figure out how to get to the axis details; I just keep going to the screen which allows me to enter a custom value for the axis.

    2. Did you opt-in into the beta testing group?

  2. It's not a new feature, but I'm confused by "set point" functions. Is there a page or link that describes how these work? I suspect the problems are mostly in my head, but points zeroing out when I touch them is not something I'd expect. I also don't see how to go back to the previous position reading (i.e. if a press a set point by mistake). Another question is I see how to remove set points, but the point count keeps on incrementing and can't figure out how to restart from 1 on a new job. Anyway, lots of questions on set points.

    1. TouchDRO uses the "working towards zero" approach. When you touch the point, you effectively set it as the incremental origin, so it's (incremental) coordinates become the new 0/0/0 point and the axis readout shows the distance to it.
      Point counter doesn't reset once the point is deleted. To start from 1, you can create a new workspace. I think I addressed this in the new (Beta) version.
      Thank you

  3. Do you have a writeup for adding a tachometer to the DRO setup? I converted my bridgeport to a DC motor and although I have figured out the speeds on the step pully, it would be nice to have a digital tach so I can use the speed control knob on my motor control

    1. Not yet. Working on it, though (firmware is ready, just need to take some pictures and post a "how-to".

  4. Great project. Will you consider adding quadrature monitoring of the spindle to allow for threading?

  5. Hi Yuriy. A nice piece of work. I am running touchDRO on a Samsung-3 tablet. This has a 1024x600 screen, but android lays out the main activity screen with the menu extension dots off-screen so the settings menu is inaccessible. I was about to give up when I found that the "home screen" button pops up this extension menu. It might be worth putting this in the doco next time you update the getting started page.