Force each stage to begin over already printed layers

[thesoundman000 0]

As per the title I'm trying to find where I force the print to begin over already printed layers. It's a problem I always run into and usually I fix it either by:

a) muddling the settings until Cura randomly decides to start the print over the layer which is a poor solution and compromises the rest of the print for no good reason.

b) manually modifying the GCode which kind of defeats the point of the automatic slicer.

 

The issue arises in several situations but notably when printing around another object which the filament won't stick to easily ie metal, wood etc. Usually when printing a flat surface over one such object there are no issues because the border and fill naturally starts over the remainder of the part however in this instance there is a hole in this overhang and I can't seem to prevent it from printing that boundary first which of course doesn't stick and ruins the print. I've attached an image of the issue at hand, this is shown looking up from the bottom with the layer immediately prior also visible. As you can see it begins printing in the middle of the air instead of running the boundary runs first for example which would solve the issue.

 

I'm pretty confident it'll be a setting given its such a common requirement but I can't find it, any pointers would be appreciated.

 

*EDIT* Note that Outer before Inner walls doesn't fix the problem unfortunately as it prints only a singular outer wall then circular wall in an alternate pattern which causes the same issues. Similarly Z seam alignment doesn't assist when it comes to the boundary layers around an internal hole as described.

Edited May 22, 2020 by thesoundman000

[Cuq 185]

This is not a Cura issue but a well known situation in FDM technology, have a look to this page for more solution.

 

https://hackaday.com/2020/05/17/look-ma-no-support-for-my-floating-holes/

 

[thesoundman000 0]

18 minutes ago, Cuq said:

This is not a Cura issue but a well known situation in FDM technology, have a look to this page for more solution.

 

Looks like you misunderstood me slightly I'll try and clarify. The layer is not unsupported as that solution presented rather it is alternately supported by a material to which the filament of choice is unable to reliably attach to. This leads to a situation where, if the print is begun over existing structure the part is completely and perfectly formed, however this cannot be achieved if the print starts in the center. The print remains completely supported but not attached in that instance.

 

Absolutely no changes to the print path are necessary (admittedly improvements could be made but that isn't the focus of this question) as manually correcting the start position such that it occurs over the prior layer is sufficient to solve the issue.

 

Overhangs in general shouldn't start in mid air, they always start on the piece and then move outwards using the pre-existent material as the base. Cura (and all slicers I've used atleast) seem to do this by default so the capability is presumably built into the software. I'm chasing what I'm hoping is a simple "begin print over prior layer" checkbox or similar setting. It would appear that doesn't exist so an option that would, in a round about manner, cause the desired outcome with minimal impact on the rest of the print is the most likely route.

 

Edit: typing on a mobile screen at 2am in the morning so please excuse any typos.

Edited May 22, 2020 by thesoundman000