blinds feeder offset problem

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Feb 6, 2021, 4:20:14 PM2/6/21
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I'm using blinds feeder with QFN44s in pockets- no tape. Part pitch is set to 8mm, but instead of seeking to the next part it will be exactly between two.

If I set part pitch to 16mm it will work, but obviously skips every other part. I've attached screenshots, machine.xml and the scad file I used


Feb 6, 2021, 4:22:25 PM2/6/21
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Text files- google groups apparently doesn't like everything in one post.


Feb 7, 2021, 3:02:52 AM2/7/21

Hi Scott

that is because you used blinds=true.

A part can only use the blinds cover, if it is sparsely laid out in the tape like the small passives, i.e. there must be a gap between parts that is larger or equal than the parts themselves. The blinds of the cover only work that way to cover the part when closed. The blinds openings must also be large enough to lift out the part, which is clearly not the case here.

You can still do that with the with the QLPF44 of course, but then you need to set it to 32mm pitch which is wasteful.

If you have space on the machine to push off the whole cover (feeder is on the edge), just use blinds=false

As you can see it then aligns the pockets differently.

For a part like this you can also switch off the cover altogether.

But this  is not in the TapeDefinition() but in the BlindsFeeder() call.

trayQLPF44 = TapeDefinition(
    pocket_width=7.1 + pocket_clearance,
    pocket_length=7.1 + pocket_clearance,

// Create the feeder array with these tape definitions.
// Note the BlindsFeeder has a myriad of parameters you can tweak, the ones used here are just the most important.
// See the Library file to learn more.
    // Tape length from feeder edge to edge, usually multiples of 4mm.
    // Other values are supported if you manually adjust the edge distance in the OpenPNP feeder.
    // Number of lanes per tape definition. 
    arrayed_tape_lanes=      [2,        ],
    // The arrayed tape definitions.
    arrayed_tapes=           [trayQLPF44,],
    // lable_length=20,
    cover = false,

    debug = false


Am 06.02.2021 um 22:22 schrieb
Text files- google groups apparently doesn't like everything in one post.

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Feb 7, 2021, 2:14:32 PM2/7/21
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Thanks for pointing that out! I didn't realize that setting also had an effect on part placement. I was printing with blinds covers so that I could quickly see how many parts were left even when covered- never noticed that shifted the pocket locations.

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