Digital calipers for the Boley lathe

Simple digital caliper
Simple digital caliper

The idea is to use a digital caliper for measuring the movement of the cross slide on the Boley lathe. A cheap digital caliper is used as a first test. For this cross slide a 150mm standard caliper is sufficient. Instead of the manual hand calipers there are also attachable calipers available. However they cost about twice as much and for this specific lathe there was no version that could have been attached without heavy modifications.

For a comfortable use a larger digital readout is required. The caliper will be hidden under some parts of the slide anyway. Therefore the caliper will be attached to a microcontroller which in turn will communicate with a small tablet to provide feedback and handle Input/Output.

The first step was disassembling the caliper and soldering four wires to its data port. (Gnd, Data, Clock, Power) Checking on the Oscilloscope showed the Clock and Data signals working and revealed the 6×4 Bit protocol used by the caliper. The second step was the connection to the microcontroller (Arduino compatible development board with ATMEGA328P-PU) using a provisory voltage divider.


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