TouchDRO for Sherline, rev 2

With TouchDRO working great with my Sherline mill and lathe for about 6 months now, a few additional features have been added to this second revision of the design:

  • compatible with CUI's AMT-102 and Sherline's 8220/8225 encoders
  • provides 5V output for charging tablet
  • absolute zero set
  • 20% reduction in PCB size
  • fully enclosed components (specifically, bluetooth and power switch)
  • setting of bluetooth module name
  • tachometer support for both Teensy 3.x and Teensy LC

Here is the updated schematic:

Touch DRO schematic

And board layout:


Eagle schematic and board layout as well as up-to-date arduino code can be found on github. The README file contains the bill of materials and an 3D-printable enclosure is included as well:

Revision 1's instructions still apply:

The git repo also has the files needed for the new 3D printable enclosure:

touch dro rev 2 case

Approach (updated)

Step 1 Buy components. Parts can be ordered from websites like adafruit or sparkfun (or their UK, Australian, etc equivalents). If you don't mind waiting a little longer for shipping, some of the components can be ordered directly from the asian manufacturers via ebay for about 50% less.

Step 2 Get the board. There are several manufacturers that will do small runs for reasonable prices such as OSHPark. Some accept the Eagle CAD board file directly or it's easy to generate the necessary gerber files using the freeware version of Eagle CAD.

Step 3 Order the enclosure. I used Shapeways to print the bottom and top of the enclosure. If you have your own 3D printer, the Solidwork CAD and STL files are included. Making your own is also an option as a project box can work too.

Step 4 Solder components. To keep the assembly simple, the PCB is designed with through-hole components. Any standard soldering iron with a small tip can be used. The board has labels that match the schematic component values; the Eagle CAD schematic is also available. The arduino-compatible Teensyduino and the HC05 bluetooth module need header pins, everything else is direct connection to the board. Note: since the PCB has its own power supply, you'll need to modify the teensyduino to separate the usb power from external source using option #1 before you solder it to the board. Also, the on/off switch, the zero set switch and power LED are off board; there are pads on the board for each of these connections.

Step 5 Upload arduino sketch. Setup files for PlatformIO is included in the github repository; this will install the necessary libraries, compile and upload the interface sketch to the Teensyduino. Alternatively, you can use the standard Arduino IDE with the teensyduino software add-on.

Step 6 Mount the encoders. If you're using a Sherline lathe and/or mill with the AMT-102 encoders, the instructions can be found here. Otherwise, the AMT-102 datasheet has the mounting information for these to be adapted to other machines. If you're using the Sherline 8220/8225 encoders, Sherline provides mounting instructions.

Step 7 Connect encoders. The PCB's bill of materials includes the connectors for the AMT-102 encoders as well as the board-compatible connectors. Or you can skip the board-side connectors since the PCB through-holes are big enough to solder 28-AWG wire directly. Either way, the pin-outs can be found for both encoder types on the schematic.

Step 8 Power up! Any 5-12V DC power supply can be used with the PCB's 5.5mm x 2.1mm barrel jack. Pair your tablet installed with TouchDRO to the HC-05 and configure it with a CPI of 163840 for the AMT-102 encoders (set at the default 4096 resolution) or 1000 for the Sherline encoders. Using a standard micro-usb cable, connect power to your tablet.

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