What it is

It is a 3 axis digital readout for milling machines or lathes that interfaces TTL quadrature encoders (Also accepts digital caliper com for Z axis)

Features:

• 8 0.56" digits display per axis
• Quadrature optical encoders interface (RJ11 sockets)
• Digital caliper serial interface also implemented for Z axis
• 2 independent reference origins
• Axis zeroing per origin
• mm/inch units
• Cartesian/Polar coordinate system representation
• 50 points memory
• Encoders input filtering
• System configuration (axis sensors PPI, axis direction inversion, decimal points per unit) can be sent by serial, using a simple GUI that I have made for Windows or just a serial terminal (JSON message format shown in picture). It is permanently stored in non-volatile memory.
• Recalculation of display values at 25Hz rate
• built as a shield for the Arduino UNO
• adjustable display brightness
• Hardware encoder signals XORing for more accurate interrupts utilization
• Powerful MAX7219 display drivers
• Fast optimized arithmetic manipulations for real time polar coordinates conversion

What you get is an assembled board including a pre-programmed MCU board. A 5V power supply with the standard 5.5x2.1mm plug (same as Arduino power plug) is needed but not included!

Why did I make it?

As a hobbyist I have been working with lathes and milling machines. DROs are extremely useful but commercial ones are too expensive, bulky and have a lot of non-practical features.

What makes it special?

Extremely compact (90mm x 150mm). Very versatile and powerful features

• Polar coordinates mode enables a big variety of tasks that usually are done by dedicated and non-intuitive features in commercial devices
• Selectable reference origins are more useful than the ABS/INC feature found in most commercial devices