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A project log for OpenPnP - Linear Rails

Open source pick-and-place machine utilizing linear rails with a cartesian X/Y gantry, built around the OpenPnP ecosystem

richard-simRichard Sim 06/17/2016 at 04:350 Comments

My goal is to be able to eventually use this machine to place components for prototypes of a wearable device. Being a wearable device, this means 0402's (plausible), 0.4mm pitch QFN's (pushing it), and 0.35mm pitch BGA's (if you have any luck to spare, I'll take it). Speed isn't much of a concern for me with the build as it's only for prototyping - but it'd sure be fun to have a zippy machine, so I'm putting that as a nice-to-have.

These requirements are beyond the performance expected out of current OpenPnP (http://openpnp.org) machines, and as such I'm designing a new machine and expect to have to add some features to the OpenPnP software as I go. The machine will be aderivative of Anthony Webb's DIY Pick and Place that he's documented (well!) here: https://hackaday.io/project/9319-diy-pick-and-place

Where I'm stepping away from Anthony's build is primarily around the design of the X-axis, which will be rotated so the 2040 aluminium extrusion is mounted vertically to minimize deflection. I've redesigned the Y-axis sleds (that hold the X-axis to the Y-axis carriages) and the X-axis's motor and idler mounts (they will now be mounted on the sleds) to allow for the X-axis to sit low enough that the top surface of the X- and Y-axis rails are inline, eliminating a moment as the machine moves. As a consequence of this change, the X-axis sled for the head will also be redesigned as the linear rail's carriage is now under the X-axis rather than beside it. The sleds and all motor and idler mounts will be machined out of aluminium for rigidity.

The downside to this change will be that there will be some a dead zone to either end of the X-axis. This may be reduced by the design of the X-axis sled and head, but it will likely be more than Anthony's machine. This shouldn't be a big deal however as it still has quite a large work area, and I don't need a huge number of feeders or trays.

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