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Manual SMT Pick and Place Machine

CNC machine and custom made stepper motor controller to manually pick up SMT components and place them on a PCB with microscopic accuracy.

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Have you ever had the feeling that electronics components are getting smaller? For a long time I thought I was just my deteriorating eyesight or maybe some kind of ergot fungus infecting my bread giving me a general 'Alice in Wonderland' effect.

I now realise that it is actually an Ai conspiracy to make electronics so difficult to build that only robots can do it!

As the saying goes: "If you can't beat them, join them" so I built this 'robot' to help overcome my bad eyesight and unsteady hands so that I can continue to build prototype circuit boards way past my 100 th birthday.

Bad eyesight? Shaky hands? Fear not the dreaded SMT components any longer! It might look complicated, but this machine is actually very easy to build!

Ok you may now be thinking 'OMG - this project is way too expensive for me' ..... Well, if that is the case, I'd have to say you're probably wrong. The CNC engraving machine which I hacked is relatively cheap, especially if you buy it direct from China (it comes as a flat pack kit). Also, there's no automation so no computer or G code is required.

This is a manually operated machine - an array of sliders, knobs and buttons are used to pick up, move the components and place them - so its all done through finger action by looking at a small video screen for the microscopic facility.

The actual CNC parts come from an engraver kit which itself is relatively cheap and easy to assemble. The PCB is easy to assemble and, of course, has no SMT parts. Seriously, if your hands aren't steady enough to work with SMT components or you just don't want to mess up a complicated board fabrication then this machine might be the solution.

Here's one example: You want to use the best performing, most cost effective components and you're either a novice or slightly disabled like me. You've got a PCB requiring 50 SMT components and you paste on the solder through a stencil and start assembling the most difficult components first with a set of tweezers and a large lump of luck. At the tenth component, you accidentally smudge the solder by inaccurate positioning and have to start all over again from scratch. This is really no fun at all!

Here's a second example: Today I wanted to build up an RF band pass filter PCB. I've been using a piece of software to design the filter and checking the tolerances required on the components before I order them. After fiddling about with the numbers for a while, I realised that some of the components need to be very tight in terms of tolerance ..... and guess what ...... they're only available in 0402 package at decent tolerances, which means the component is 1mm long! Tweezers? ..... Forget about it!

Pick_and_place_11.ino

Arduino file

ino - 4.48 kB - 05/11/2017 at 16:21

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Adobe Portable Document Format - 592.32 kB - 05/11/2017 at 11:49

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instructions for assembly of CNC kit 01.pdf

The 3 Axis CNC engraving machine comes as a self assembly kit. This part of the instructions is not my work - these instructions come with the kit.

Adobe Portable Document Format - 19.23 MB - 04/30/2017 at 15:22

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Stepper motor controller 04.pcb

PCB design software opens with Design Spark PCB design software (FREE download).

pcb - 269.50 kB - 04/27/2017 at 16:11

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JPEG Image - 653.83 kB - 04/27/2017 at 14:11

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View all 20 components

  • PCB Faults

    TegwynTwmffat04/24/2017 at 12:15 0 comments

    Although the PCB is fully functional, I thought I should make a list of the errors before I forget:

    • Rotary potentiometers upside down - cosmetic
    • Toggle switches upside down - cosmetic
    • Lug mounting hole for slider in wrong place - non-critical
    • Board outline doesn't follow USB and power sockets properly - cosmetic
    • Schottky diode missing between 12v supply and Arduino Vin, which was supposed to prevent the Arduino trying to accidently run the motors through it's own power supply - non-critical but potentially damage could be done to the ARduino due to user error.
    • LED resister incorrectly labelled as 10K and should be 1K - non critical.

  • Controller fully operational

    TegwynTwmffat04/22/2017 at 15:14 0 comments

    Well that was the easiest de-bugging that I've ever done. No more motor vibration by employing mega amounts of oversampling and float to integer conversion in the code and no more hot chips due to motor's power not turning off - again, an easy coding solution was found. My only disappointment is that the project was way too easy and not really much of a challenge, but this does mean it will also be easy to replicate, which is a good thing ..... And, of course, it will be a very useful tool for people with poor eyesight or unsteady hands .... or both.

  • PCBs arrived today

    TegwynTwmffat04/20/2017 at 19:05 0 comments

    The PCBs for the controller arrived today so I soldered up some of the components and tested it out. There were a few small non-critical design errors but actually it worked a treat except that I noticed that the current through the L293E's did not drop off when the stepper motor was not being used. The previous breadboard configuration was too chaotic to notice such things and I'm sure there is a simple explanation. Must dig out the L293E datasheet and look for some clues.

  • Vacuum Needle

    TegwynTwmffat04/13/2017 at 11:29 0 comments

    Currently I am attaching a vacuum needle to the 4th stepper motor and designing the finger operated control board.

    Control panel now has 2x L293E stepper motor controller chips controlling 2 stepper motors. The circuit works but may need snobbery diodes and filter capacitors to operate reliably - the motors vibrate slightly (this was actually solved by oversampling by about x100 in the Arduino code).

    The vacuum needle system has been fabricated with two brass fittings made by my own hands on a lathe (see photo). It uses a special air fitting that has a rotating stem on a static banjo: 4MM X 1/8" NPT FEMALE SINGLE BANJO, Kelm One Touch Plastic Push-in Fittings. A standard T fitting would not work as the pipe would get tangled up in the machine as the needle revolves.

    The whole machine needs to be extended upwards by about 60mm so some extra lengths of 2020 aluminium profile have been ordered. In the meantime, the control board needs to be hardwired onto proper PCB - Too many diodes and general breadboard frenzy has meant too many chances of shorts/bad connections. No worries though - I have space Hackable Prototyping PCBs just for this kind of situation :)

  • Controller Boards on their way from China

    TegwynTwmffat04/11/2017 at 18:43 0 comments

    My friends at Sitopway have very graciously accepted my dollars and agreed to send me some circuit boards YAAYYYY! Apart from the 4 controller chips, the design has an incredibly vast array of knobs, buttons and sliders .... and ..... yes ..... an LED!

  • 4 axis controller PCB

    TegwynTwmffat03/19/2017 at 10:33 0 comments

    There's going to be a controller board available at some stage if anybody wants one?

  • Machine is working!

    TegwynTwmffat03/17/2017 at 17:25 0 comments

    The machine is now working!

    Actually, it works really well with really good precision. The video below shows it in action:

  • Control system now working

    TegwynTwmffat03/15/2017 at 08:50 0 comments

    The machine can now be controlled by fingers!

    I revamped the breadboard circuit (3rd time) and got all 4 axis's working using an Arduino Mega 2560 and four L293E motor control chips. 8 of the analogue ports had to be used as digital ports, which was fine. The chips themselves are really easy to figure out and the connections are essentially symmetrical in 2 dimensions.

    The four push buttons, bottom right, allow any particular motor to be turned on whilst the others remain off. The potentiometers allow coarse and fine control.

    Next job - extend the main upright frame upwards by about 50mm to allow the needle to be attached. Then connect the vacuum tube and test it out!

View all 8 project logs

  • 1

    Since we're going to actually hack a pre-existing product - a shop bought CNC engraving machine - the first step is to assemble the CNC engraving/laser machine - it comes as a kit with instructions of it's own (see below). The upright aluminium 2020 sections need to be replaced with longer ones - 300mm - so that there is plenty of height for the vacuum needle. The engraving motor is not used and is replaced with the 27:1 stepper motor, which then rotates the SMT component (A axis). Fortunately, I was able to find a motor that fitted perfectly into the same hole so no machining was necessary other than drilling the four mounting holes. The instructions for the engraving machine assembly are HERE in the 'files' section.

    Video for engraving machine assembly is here (this is NOT my work - we're going to hack this machine to do pick and place)

  • 2

    This step is slightly more difficult as it involves some machining. The microscope stand is turned upside down and the base plate machined with a hole big enough for the Z axis motor to pass through unobstructed.

    Take the square base plate as in the photo below and drill holes to suit the stepper motor that fits above it:

    The photo below shows it's final position:

    The photo above shows the A axis motor on the right and the Z axis motor above, passing through the microscope mounting plate. The machining is best done on a lathe in a four jaw chuck although I actually used an industrial magnetic broaching drill. Another identical base plate can be mounted at 180 degrees to allow 2 microscopes to be used simultaneously. The use of 2 microscopes is highly recommended as accurate 3D positioning is very difficult without them both.

  • 3

    The arm attaching the microscope needs to be unscrewed from the banjo fitting on the vertical tube and carefully bent to exactly 125 degrees as in the photos below:

View all 8 instructions

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