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Build a 4-axis wireless DRO adapter for your mill or lathe. The TDK-40 supports RS-422 and TTL quadrature scales (glass, magnetic, and inductive) and uses the same 32-bit architecture and differential input circuitry as our pre-assembled TDA-4xx adapters. Pair it with an Android tablet running TouchDRO and you have a full-featured digital readout system.
Need a touch probe input, tachometer, or reference marks? The DIY kit doesn't include these — see the DRO for Milling Machines or DRO for Metal Lathes for pre-assembled adapters with full input options.
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.
Choose Your Option
This page offers four options — from a complete kit to individual components — so you can choose how much DIY you want. Options that include the pre-programmed module come with TouchDRO Plus firmware pre-installed.
- 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.
- Module — Pre-programmed ESP32 module only. Drop-in replacement for an existing kit, or use with your own carrier board.
- Main PCB (Populated) — The TDK-40 carrier board only, assembled and tested. Add your own ESP32 module, connectors, enclosure, and wiring.
What's included (Full TouchDRO Kit)
- Partially assembled TDK-40 main board
- ESP32 DevKitC module preprogrammed with TouchDRO V3 Plus firmware
- Custom 3D printed enclosure kit
- A set of DB9/D-Sub 9 female connectors with mounting hardware
- 4x2 pin headers and pre-crimped jumper wires for connector wiring
- Access to TouchDRO Plus application for advanced DRO features
- Support for Mitutoyo SPC and BIN6 data protocol (adapters sold separately)
For Module or Main PCB only, see the option descriptions above or the standalone product pages: ESP32 Module | TDK-40 Main Board
Supported DRO Scales
The adapters support DRO scales and rotary encoders that output a 5V quadrature signal. This includes:
- Majority of modern optical, magnetic, and inductive digital readout scales. Learn more
- 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)
Frequently Asked Questions
Does the TDK-40 support a touch probe, tachometer, or reference marks?
No. The TDK-40 is designed as a 4-axis scale interface only. If your workflow requires a touch probe input, tachometer, reference marks, or power-loss position backup, see the DRO for Milling Machines or DRO 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.
Will this work with my scales?
Most likely yes. The TDK-40 supports 5V quadrature signals (RS-422 differential or TTL single-ended), which covers the majority of modern glass and magnetic DRO scales. Mitutoyo SPC and iGaging Absolute scales require separate input converters (sold separately). If you're unsure, check the compatible scales page before ordering.
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.
Module: Pre-programmed ESP32 only. Drop-in replacement for an existing kit, or use with your own carrier board.
Main PCB: Populated carrier board only. You supply the module, 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. Module-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.
