5th elemenet
Posts: 1
Joined: Mon Feb 04, 2019 11:05 am

Perimeter printing order.

Mon Feb 04, 2019 11:39 am

I figured that this would have been solved by using the 'outline direction' option, but it is not.

If you are printing thin walls, such as just two extrusion paths wide, the slicer chooses to print the outside wall before the inside wall regardless of how you have things selected.

For example with the attached image.
outsidelayer.JPG
It will always choose to print the outside wall, then go for the inside one.

This can be a problem. If oozing occurs on the travel move towards the start location of the outside wall and material has been wicked out of the nozzle end, when it comes to start printing the outside wall the printer extrudes but nothing/very little material actually comes out. The 'extra restart distance' option is there to help combat this, but can be next to useless as it doesn't take into consideration the distance travelled. Obviously if the nozzle travels a short distance you only need a small amount of extra restart distance, but if it's travelled further, you need considerably more restart distance. One static value isn't enough to compensate accurately for this issue. It should scale with distance travelled.

To help combat this issue, if it's possible to optimise so the machine goes for an inner perimeter line first, then do the outer line (as the travel move between the inner and outer line would tend to be very small, but currently the move from the previous layer to the new outer line can be very large, it would reduce the print quality loss of having no material in the nozzle.

I've been paying attention to print quality of thin walled things I've been printing and this issue crops up in every single one. A decent travel move precedes the slicer starting an external perimeter line and you end up with a quality issue where it does so. Whereas if you look at the quality of the inside perimeter line it's always almost perfect because it tends to do the inside perimeter line directly after the external perimeter line without any/very little of a travel move.

So to wrap up -

1) have a feature to have the slicer to do the inner perimeter line before the outer perimeter line with thin walled objects.
2) have the ability to modify the 'extra restart distance' option so that it takes into consideration the distance actually travelled, so that it uses a small value for short distances and scales linearly, to use a larger value for longer distances. Obviously up to a maximum amount regardless of how far you've travelled.

Many thanks,

Matt.

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