Robin's smt Pick and Place build

[flippersplace]

Hi, I'm in the middle of a similar project. So far I am good for 0805 parts, 3216 LEDs, SOT23 parts.

Re your query about software:

Mine does not have a vision system, it simply depends on accuracy of the machine driven via Mach 3 and GCode. But I don't do manual GCode.

I have a Excel Workbook with a separate spreadsheet for:
- Heads
- Feeders
- PCB Array offsets
- Each PCB
- GCode output

For each PCB I paste in the Pick Place export from my PCB CAD package. I manually redit rotation, and enter a head and feeder. I paste in a block of formulas alongside.

I then manually enter a step sequence (gives a small leeway to optimise pick up order for efficiency)

The aforementioned formulas reference the Head & Feeder sheets to calculate pick and place offsets for each head/feeder combination, and place offsets for each head/refdes combination

I also update worksheet PCBArray with the PCB name and no of PCB's in X & Y directions for this assembly run.

I then run a macro over the above which for each rotation generates GCODE to:

- Initialise all Mach 3 variables used per feeder to keep count of the the next component to come out of that feeder

Main loop:
- Pauses waiting for operator (me) to place the PCB array holder and use the USB camera to zero offset G55 to the PCB holder calibration point
- calculates and sets an offset for each PCB in the PCB array relative to G55 offset for that rotation
- creates calls to the GCode pick place subroutine for all refdes in this rotation
- creates the GCode pick place subroutine called above

= Repeat until all rotations processed

Once a PCB is setup in the workbook (which only takes 5-10 min) can be tweaked quickly, ie if a head is faulty I just edit the heads per refdes and rerun the Macro.

Seems to work so far.

[Robin Hewitt]

Hi, I'm in the middle of a similar project. So far I am good for 0805 parts, 3216 LEDs, SOT23 parts.

Must have missed the e-mail notification.

What a splendid looking machine, is that a multi-nozzle head?

[flippersplace]

Yes its morphed into a bit of a monstronsity. Although I've still a few hundred PCB's to finish running through this machine I've already started collecting bits ready for making a new one based on the experience so far. This one has 24" X & Y screws and I will stay with that size for the new one. The primary factor for speed I'm finding is lower mass, so I'm thinking an overhead gantry type machine, with 1-2 heads on each side. Heads to be pneumatic preferably for both weight, speed and built in 'give' via compression.

For rotation, I think it's actually just easier to automatically rotate the PCB's base rather than each head, particularly as my Excel GCode generator groups sets of pick place operations per each rotation already. Automatic component feeding is always in the back of mind but thus far is not necessary.

But, what I'm really interested in is fast / light mechanisms for centering components, mounted on each head...