WISHLIST: Selective Hole Horizontal Expansion areas (are they possible?)

[Aus67 0]

The new Hole Horizontal Expansion option in Cura 4.8 is a great feature. However, currently the feature is applied to the entire print, so many non-holes areas that are technically 'a hole'  are affected as well (see the attached snippet). 

In the pic attached the centre shaft hole of the gear is too small (but the outside diameter of the gear is the correct size). So we apply Hole Horizontal Expansion to enlarge the diameter of the centre gear hole 0.6mm. 

The problem is the outside diameter of the gear is now 0.6mm smaller as the hole expansion has been applied to it as well. 

 

Would it be possible to tell cura where I want the Hole Horizontal Expansion applied?? Maybe by applying a mask like in the second attachment. So the shaft hole increases 0.3 but the outside diameter doesn't shrink 0.6mm?

 

Maybe this feature could be applied to a future version of Cura??

[ahoeben 2,010]

This should already be possible using the Per Model Settings tool, see https://support.ultimaker.com/hc/en-us/articles/360012031399-How-to-adjust-print-settings-per-model-in-Ultimaker-Cura

 

Load an additional model and overlap it with the main model (or create a support blocker as a shortcut). Then select the Per Model Settings tool (the one above the Support Blocker tool), and set the added model (or the support blocker) to "Modify settings for overlaps". Set the option for "Cutting Mesh", and then add the Hole Horizontal Expansion setting and adjust its value. Caveat: you will get additional walls.

[Aus67 0]

Hey thanks for the reply ahoeben!

 

Yes in the simplest form your suggestion should work, but it is a lot of work and added printing time.  however due to the nature of the horizontal hole expansion basically working on every internal polygon of the part (which includes circles) I need to be able to select just the polygon to expand. 

 

I have attached a picture to highlight what I mean. The attached is one piece and so in its current form the horizontal hole expansion will act on every polygon (marked with the white dots) because each complex shape is a polygon. 

 

I still hope to be able to be selective in which polygon the expansion is applied to. This will overcome the inherent design floor in how these 3d printers work and why the holes are smaller in the first place. 

 

[chillipepper68 0]

Hi @ahoeben,  There is a simpler use case where the current horizontal hole expansion would be improved by allowing for selective polygons.   The attached picture is a hole in a hole scenario.  It is a subset of a larger model.  In my larger model, the larger hole secures the model to a pipe.  The smaller hole is for a screw to secure the model to the pipe. 

 

If horizontal hole expansion is set to the model then a raised band occurs within the larger hole.  It is noteworthy the band is exactly the diameter of the smaller hole.  It would appear the slicing algorithm is challenged with this scenario.  The inner diameter of the larger hole is also increased by the horizontal hole expansion amount.  Both are undesirable results.  The desired outcome is for the inner diameter of the larger hole to stay at the specified diameter, and the smaller hole be expanded to truly accommodate an m4 screw.

 

I've also tried the blocking feature in Cura using the 'modify settings with overlaps' with 'cutting mesh' approach.  It appears the horizontal hole expansion value is not honored.  To test I increased the value of the blocking feature to a larger horizontal hole expansion value and the resultant print showed no change in diameter.

 

Are there other options?  A new feature to selectively configure which holes the setting is applied to, or not applied to would be very beneficial.

 

Thanks.

[gr5 2,265]

In my experience horizontal holes always come out perfect already.

 

I'm just wondering if that "ring" inside the cylinder is caused by something else - is that ring also visible in PREVIEW mode?

 

I've seen many people use too much retraction or "z hop" either of which could cause that ring only where the horizontal hole is (because only at the hole does the printer potentially do a travel move with retraction).

[chillipepper68 0]

The ring appears in the preview.  Attached are two pictures from my original model.  A larger cylinder hole seems to make the ring more pronounced.  In a hole 34mm in diameter the ring bump is about 1mm.  The example shared previously was 20mm  in diameter and that bump is about 0.5mm.

 

I'm running Cura v4.8.0

[gr5 2,265]

Ah.  Yes.  Got it.  Software isn't as smart as people.  How the programmer detects "horizontal hole" in software is tricky and which walls of the hole to expand - also tricky.  I would avoid this feature.  Maybe change hole size in CAD instead.

 

That's what they do in injection molding.  Typically you send your CAD files to the manufacturing plant and they alter everything to make it work with injection molding.  90 degree corners are no longer 90 degrees and dozens of other little changes to the model.  With 3d printing you kind of have to fix a few things like this yourself.

[chillipepper68 0]

Thanks for the clarification @gr5  I wanted to explore the options first before readjusting my hole sized in the CAD for 3d print purposes.

 

It would still be nice in the future if Cura could allow for user selected hole modification for this setting.  In my use case as a hobbiest, I'm going to make the .stl files available to others.  If they could adjust to their printer/material in the slicer, that would be optimal.    Outside of the 90 degree corner scenario I'll add that the horizontal hole expansion feature is slick.

 

Thanks again.