These pages contains the design of an open source PnP machine and details on how to buy and build the machine. This is still work in progress.
This machine “as is” can take more than 100 x 8mm Feeders if all 4 sides are used + have plenty of work-space left. The illustration is with 4 needles, but it can be fitted with 2 needles (less space), 8 or 16 needles (faster assembly). The machine is all metal and intended to be bolted to the floor and hidden inside a dust-free cabinet to support 0201 and be part of an assembly line. Parts of fittings, outer cabinet and control system is still missing on the drawings. One of the key decitions is to use standard 2020 frames and avoid tailoring them so we can re-use them if the machine changes.
This needle design is straight forward to make and is 21mm wide per needle, meaning that 2 needles are 41mm wide and 4 needles 83mm wide – the drawing uses a standard 100mm wide backplate, but this cane be optimized. Size in width and depth was an objective in the design. Nema8 is used to rotate the needle, while a Nema11 is used to lift needle up/down. The travel distance is 3 cm which is sufficient. It uses Nema11 steppers to move needle up/down, but can also be fitted with Nema17 steppers for that purpose if needed. What is lacking is tank-belt and manifold for pneumatic.
This head is 99% mechanical made of aluminium with minimal need ot work. All parts are bought “as is” and mostly only require precition drilling. This was done to achieve speed/stability to support 0201 components.
The feeder is small and the 8mm tape feeder is 12mm wide. This is mostly 3D printed plastic and for the time being an experimental design that is not tested yet. Manual testing by hands feels ok, but it needs to be tested on an actual machine. The green plate is the control system and it lack a connector to the machine yet. An important part of the design is that it is a smart feeder, meaning it holds memory of what is on the tape and the machine knows it’s position so that the feeder becomes plug & play. The sprocket is combined with a gear and 3D printet. Tests prove that works out well. The yellow plates are light sensors for the encoder that we need to tailor to make them fit within 12mm.
Control system is a bit loose ends yet. We will use OpenPnP and most likely Duet3 – that will take care of the main machine, but we lack a solution for Feeders and other actuators/sensors. The initial plan is to use CAN in groups of 4 to 16. Using an ECU as CAN Gateway between OpenPnP and Feeder’s will give us 7 networks + we can add another 7 with a 2nd GW to scale up. Using ECU technology add the capability to add actuators and sensors as we please. It might be that we need some custom solutions to optimize cost a bit.
Duet3 was chosen because it is a capable board that don’t require any programming. Functions on Duet3 are configurable which should make a tailored machine easy to set up – no coding. This will soon be put to test as building the main machine with 2 needles are the main priority. Part of that is that we need to test the needles to see if that design work as expected.
An early block diagram of the control system is illustrated below.
The core PnP machine should be mostly wiring and configuration and will be up running soon. The feeder system is still work in progress and is not needed as we start with trays and strips.