VacuumPick

DIY vacuum pick up project for hand SMT assembly.

The hardware is based around an inexpensive air pump, 3 valves and a controller board utilizing the ATTINY806 microcontroller.
Firmware is available as PlatformIO project (sources) and a precompiled hex file.
The enclosure and the handle was reused from a damaged Ayoue932 vacuum pick up.

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Operation

• vacuum activated using a touch button on the handle or a footswitch
• Button 1: Vacuum mode
• Button 2: Clean/air blow mode for cleaning the nozzle
• Button 3: pump always on mode
• 0-100% pump speed control using a potentiometer

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Electronics

• ATTINY806 MCU
• 3 x open drain MOSFET outputs for valve controls
• 3 x illuminated button inputs
• Footswitch or handle button input (incl. 5V power for touch sensors)
• Pot input as motor speed control
• UART TX/RX for debugging purposes
• I2C header for future expansion
• UPDI programmer input
• 12V DC 1A input power requirement

Board is designed in KiCad 6.0, available as project and generated gerber files.

Schematic

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Mechanical design

Design is done using FreeCAD:

The main parts are:

• Base plate used to mount the pump holder and the rest of the assembly (see MountingPlates)
• Top plate used to mount the valves
• 2 part 3D printed pump holder (step files are available)
• Valve holder - 3D printed part
• Various hardware: M3 standoffs, screws, locknuts, etc.

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System

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Handle

Pump can be controlled using either a footswitch or a button installed directly on the handle. The latter is my preferred method which i'm quite used to. I decided to install a capacitive touch button near the hole on the handle achieve two things:

• a slight move of the finger covering the hole enables the pump and increases the suction force
• to release the part all i need to do is to move the finger out of hole, this stops the pump and releases the part.

The touch sensor is made of a piece of thin copper clad and uses the TTP223D-MA6 capacitive touch button IC. There are a few variants of the TTP223 chip, some having an option for open drain or push-pull output. The one i have has one control pin only (momentary/toggle operation) and an open drain output. The board is designed to work with this type of the output, so in case you are using a different model, make sure it's properly configured.

This is a small board i designed for the TTP223-MA6 chip. Important feature is the touch sensor sensitivity adjustment using a small 0 - 51pF 0603 capacitor placed in parallel with the input. Experiment with a value to get a desired button response. In my case (handle made of metal) i had to add a 47pf cap to make it work reliably. Otherwise even touching the handle would enable the pump.

Once installed everything was secured using a heat shrink tube.

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VacuumPick in action:

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Copyright 2021 by Piotr Zapart
www.hexefx.com