Violating soft limits during nozzle tip change

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JW

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Apr 20, 2024, 9:58:03 PMApr 20
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I have an oddity in the first version of my machine, due for fix in a future version, whereby I can crash nozzle tips into the nozzle holders. It's unlikely due to placement, but possible nonetheless.

Is there a way that I can configure the soft limits to prevent XY motion into the nozzle tip changer (which is located right along the front of the bed), but then allow/force a violation of these soft limits during a nozzle tip change?

The 4-step nozzle tip sequence is safe and does not crash into the holder, but an XY move through the nozzle tip holder with Z==0, or Z<0, will crash the tip.

Ideally the keepout zones discussed here https://github.com/openpnp/openpnp/issues/308 would be great, but I understand the rationale for not implementing those.

mark maker

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Apr 21, 2024, 4:17:09 AMApr 21
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> Is there a way that I can configure the soft limits to prevent XY motion into the nozzle tip changer ..., but then allow/force a violation of these soft limits during a nozzle tip change?

No.

The smart thing to do (in my case it took a brutal crash to learn) is to sink the nozzle tip changer into the table. Seen here (among other things):

https://youtu.be/9uFxV1-vnXw

_Mark

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JW

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Apr 21, 2024, 5:47:46 AMApr 21
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Hi Mark,

OK, well thanks - good to know.

Sinking the changer is what I intend to do long term, I just can't do it right now due to an oddity with the machine structure. I'm converting an existing manual machine I built a few years ago, to get my head around OpenPnP, learn the 'gotchas' etc before building 'the big one'.

My changer is positioned front left, and I home at back left, so there shouldn't be any reason a move is ever commanded that'll crash the changer, I don't think...

Thanks for your info!

JW

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May 12, 2024, 9:43:51 PM (7 days ago) May 12
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Looks like this might now be possible with RepRapFirmware Release 3.5.1, using M599.

Not exactly sure yet how to 'cancel' the keepout zones, but fundamentally I'm thinking configure a keepout zone, then in the G code used to perform a tool change, disable the keepout zone, then re-enable it when done.

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