Z limit switch hitting during placement / pickup (rmod)

[Knas]

I have an issue that the Z limit switch is sometimes being hit during pickup / placement of parts, it seems to me that the needle goes unnecessarily far down and miniscule difference in height on component placement / pickup Z position makes the switch trigger. I would assume the Z backoff value is supposed to be used for this but it seems to be ignored during pickup / placement? Anyone have any ideas of why this is / how to fix it?

Furthermore i'm wondering why the pickup / placement Z is being zeroed in between each new run / each first placement of parts even if those positions are set in the tapes file? This seems to just add an unnecessary lag, is there a reasons for this?

Thanks

[JuKu]

I have an issue that the Z limit switch is sometimes being hit during pickup / placement of parts ... Anyone have any ideas of why this is / how to fix it?

I'll have a look at the software if it can be made more robust. In the meanwhile: The tube and switch mechanics may be tuned so that the switch is only marginally released and triggers again on its own. Also, the vacuum switch may be coupling to a switch line, giving a false trigger.

Furthermore i'm wondering why the pickup / placement Z is being zeroed in between each new run / each first placement of parts even if those positions are set in the tapes file? This seems to just add an unnecessary lag, is there a reasons for this?

You are right, the software is overly conservative. It does not know the height of the components or the PCB thickness, so it measures this on the fly at first component in a run. But you are correct, if the components are the same* the PCB height is the same** and the needle is the same***, re-measuring is unnecessary. I need to think about this.

*: Height should be reset only when reloading the tape or component type is changed (currently, the latter is not in the tapes data).
**: I have used other than standard maybe once every five year or so...
***: I haven't looked how much variation the different needles have or how much variance changing a needle (and twisting it a bit tighter or looser in the Luer connector) brings in. It has little importance as long as the height is measured but if that step is skipped, it might need consideration.