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When utilizing a guide machine device akin to a lathe or milling machine, there could be loads of strain to learn the place and feed the axes on the appropriate price. That’s why trendy machines sometimes have some type of digital read-out (DRO). [Stefano Bertelli] has created a easy Raspberry Pi based mostly DRO with a further twist, that of a linked motor drive output.
Realtime encoder place studying and motor management are greatest performed with a devoted microcontroller, ideally with a correct RTOS.
The axes that have to be monitored ought to be mechanically connected to a place sensor like a linear encoder or a rotary kind. Utilizing a linear sensor with a linear axis as an alternative of a rotary encoder on the downstream dial is best. For the readout unit, [Stefano] used a WaveShare 7-inch touchscreen module with a Raspberry Pi 3 for the UI of the readout unit. The Pi has a custom-designed HAT, that performs energy conditioning and offers a strong RS485 interface. Linked through that RS485 hyperlink is one other {custom} PCB based mostly on an STM32F411 with just a few supporting energy provides and interfacing parts. The job of this board is to interface to the place encoders, studying positioning pulses utilizing interrupts. There’s a further stepper motor drive courtesy of a ULN2003 Darlington driver to permit the management of a single motorised axis. An extra motor driver module is required, which ought to be no shock since driving a milling machine axis would require a reasonably beefy motor. This GitHub repo comprises the FreeRTOS-based firmware for this board. This motor drive has the power to be related to a measuring axis in a programmable method, enabling one axis to be adjusted to observe or soar in managed steps with one other. This characteristic can considerably simplify sure kinds of machining operations, as [Stefano] elaborates within the video.
Lastly, the Raspberry Pi runs a easy Python software with Kivy for the GUI. As [Stefano] explains within the video beneath, this makes debugging and modification fairly easy.
Including DROs to an older machine is an apparent however useful hack. Right here’s one other approach to do it. If that’s an excessive amount of work, then you would simply hack a digital readout calliper in there.
Because of [paulvdh] for the tip!
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