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4 Axis Do-it-Yourself DRO
Complete Kit – Requires Assembly

Easy-to-build 4-axis DIY wireless DRO scale interface kit with tachometer input for milling machines and metal lathes. Connects to the TouchDRO Android app via Bluetooth. Compatible with most modern and legacy DRO scales, including glass, magnetic, iGaging, and Mitutoyo SPC.
$149.00 USD
$149.00 USD
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  • Ships in 2-5 business days
  • Shipping: $9.99 USD
  • No warranty
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The TDK-40 DIY TouchDRO kit lets you build a 4-axis wireless DRO adapter with tachometer input for your mill or lathe. It reads RS-422 and TTL quadrature scales (glass, magnetic, and inductive) as well as iGaging and Mitutoyo SPC protocols using compatible input converters (sold separately). The kit uses the same 32-bit architecture and differential input circuitry as the pre-assembled TDA-4xx adapters. Pair it with an Android tablet running TouchDRO and you have a full-featured digital readout system.

Please note: These are DIY products for hobbyists with electronics experience. Assembly requires soldering, wiring, and mechanical work. We test every module and board before shipping, but self-built units are provided as-is with no warranty.

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Choose Your Option

We offer the kit in two configurations: a complete kit with enclosure, connectors, and wiring, or just the main board and pre-programmed module. Both include TouchDRO Plus firmware.

  • Full TouchDRO Kit — The complete DIY path. Includes the TDK-40 main board, pre-programmed ESP32 module, 3D-printed enclosure, DB9 connectors, headers, and pre-crimped wires. You add scales, power, and do the assembly.
  • DIY Set: Module + Board — Just the electronics. Includes the pre-programmed module and populated main board. You supply the enclosure, connectors, and wiring.

For Module or Main PCB only, see the option descriptions above or the standalone product pages: ESP32 Module | TDK-40 Main Board

What's Included

Both Options

Full Kit Only

  • Custom 3D printed enclosure
  • A set of DB9/D-Sub 9 female connectors with mounting hardware
  • 4x2 pin headers
  • Pre-crimped jumper wires for connector wiring
  • Mini-DIN 4 female connector

You'll also need

  • A set of compatible DRO scales — see recommended scales
  • An Android tablet — see our recommended tablets
  • A tablet mount
  • A 5V USB power supply (powers both the adapter and the tablet through a USB hub or splitter)

Compatible Scales

The TDK-40 kit supports the same scales as our pre-assembled TDA-410 and TDA-420 adapters. This includes most modern and many legacy optical, magnetic, and capacitive scales. Any scale that works with those adapters will work with the kit (minus the reference signal). For scales that output a quadrature signal, you can either use one of our adapter cables, or wire them directly using an appropriate input connector. The compatible scales page has the list of scales we've tested so far, and the linked brand-specific pages include pinout information and mating connectors.

For scales that use non-quadrature protocols, input converters are available:

  • Mitutoyo DigiMatic scales with SPC output – requires a SIC-5V-MIT-A input converter (sold separately)
  • iGaging Absolute DRO Plus scales – requires a SIC-3V3-IG-A input converter (sold separately)

If you don't have scales yet, see the DRO Scale Selection Guide to choose a scale type, and Recommended DRO Scales for specific models and suppliers.

Specifications

  • 4 Quadrature A/B scale inputs (5V TTL, RS-422, NPN, PNP, or Push-Pull quadrature)
  • Supports Mitutoyo SPC, iGaging EZ-View, and BIN6 serial scales (input converter required, sold separately)
  • 1 spindle RPM input
  • Bluetooth 4.2 (Classic)
  • 5V Micro-USB, 1A supply recommended

Frequently Asked Questions

What's the difference between the DIY kit and a pre-assembled TDA adapter?

The kit and the TDA-4xx share the same 32-bit architecture, scale protocol support, tachometer input, and TouchDRO Plus features. The pre-assembled adapters add touch probe input (TDA-420), reference mark support, power-loss position backup, 5-year warranty, and full technical support. If you enjoy hands-on electronics work, the kit gets you there for less. If you'd rather skip the soldering, seeDRO for Milling MachinesorDRO for Metal Lathes.

What's the difference between TouchDRO Plus and TouchDRO Community?

TouchDRO Plus is included with current-generation TouchDRO hardware (including TDK-40 kits and modules) and adds workflow tools like file import/export, image overlays, and automation features. TouchDRO Community is for legacy and fully DIY/third-party builds—it includes the essential DRO workflow but not the advanced Plus tools.See Plus features.

What do I get with each option?

Full Kit:The complete DIY path—main board, pre-programmed module, 3D-printed enclosure, DB9 connectors, headers, and pre-crimped wires. You add scales and power.
Module + Board:Just the electronics—pre-programmed module and populated main board. You supply enclosure, connectors, and wiring.

How long does assembly take, and how much troubleshooting should I expect?

With scales already mounted, most builders get a first stable reading in 1–2 hours with the Full Kit. Electronics-only builds take longer. DIY builds are most sensitive to wiring, grounding/noise, and connector work—if you want the lowest troubleshooting risk, a pre-assembled adapter is the fastest route.

Can I use this with a Windows PC, iPad, or iPhone?

No. TouchDRO runs exclusively on Android tablets. The TDK-40 communicates via Bluetooth to the TouchDRO Android app. It is not compatible with Windows, Linux, or iOS devices.