Arrange feature - instance print order/positioning improvement (re: Complete individual objects, enabled)

[Jaxx005]

Version

Version 2.3.0+win64

Operating system type + version

Windows 10 Pro N
Version 10.0.19042 Build 19042

3D printer brand / version + firmware version (if known)

Standard factory Prusa MK3S (purchased 2020).
Firmware version: 3.9.3-3556

Behavior

1. Print setting >> Complete individual objects ("CIO") >> ENABLE
2. Add instances (eg six of single body)
3. Arrange

The Arrange function correctly heeds the 'CIO' setting and spaces instances correctly...
However, the order/positioning on the bed seems 'unusual', not as expected (the logic is unknown/unclear)

The instances on the bed (eg six instances) were: two rows (across bed) x 3 deep

The print order was:

• front to back
• to left
• to front again...
• etc.

Problem

This is OK for short models that are below the wiring loom (at the rear of the printhead).
However, for taller models, this may cause the wiring to catch an already printed instance.

Current work-around

The instances are numbered and printed in that order, so each instance needs to be re-positioned on the bed, to match the print-order above.

For example:

last row........ [6] [5] << 5th and 6th instances
next row...... [4] [3]
front row..... [2] [1] << first instance on the right

This manual process is awkward rather than complex, but:

1. it 'voids' the Arrange function (which would obviously revert to the old print order!)
2. requires the user to Preview in order see the print-order of instances
3. requires the user to manual reposition instances, clear the collision warnings, and repeat until all OK.

Suggested Improvement (&/or clarification of logic? )

Arrange (certainly when CIO enabled) should perhaps:

1. print the front-most instances first (leaving the bed always clear behind)
2. then print from the righthand side (leaving the bed always clear to the left, reducing collision with sensor wires)

Comments:

CIO and Arrange are brilliant features, but I think this change/option could make it more effective, safer and less wasteful too?

CIO has saved me many hours - especially when the last (e.g. 6th) instance is the one that fails near to its completion!

Project File (.3MF) where problem occurs

No 3MF file included - it's easy to replicate with any single object and multiple instances etc

screen shots

Added 3 screenshots - showing manually positioned instances

Hope that all makes some sense! :)

Thanks.

[Jaxx005]

Additional/update:

Further screenshots - showing the order given by Arrange funtion:
Especially note that instance 5 and 6 (printed last) are in front of the other already printed instances, so rear wiring is likely to strike the instances 1 and 3 (second row back). ££££ :(

[echo465]

This is similar to #486 - but with instances you can't drag/drop to change the printing order.

[Jaxx005]

Yes, #486 (closed?) seems to be similar problem but for Objects, not Instances.

The Arrange issue seems the same is both cases: both Instances and Objects are not positioned optimally/logically as outlined above?

[lukasmatena]

Arrange and crash detection for sequential printing was improved in PrusaSlicer 2.9.1-alpha1. I believe it solves this issue. Your feedback is welcome. Closing.