Part WB Loft vs PartDesign WB Loft - hollow lofts?

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quiret
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Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by quiret »

I have been trying to create a hollow loft using FreeCAD using the Part WB. For that I created two faces which have a hole and tried to apply a loft between them. You can see a good idea of what I mean in this informative video:

phpBB [video]


Such an idea is very intuitive. But I find that it is impossible in the Part WB. When I did my research on why then I stumbled upon the following phrasing inside of the Part Loft documentation:
The sketch must contain only one open or closed wire or line (can be multiple lines, if those lines are all connected as they are then a single wire)
This sounds to me as if hollow lofts are not really feasible using the older Part WB. But as you can see in the above video the same thing is entirely possible in the PartDesign WB. Thus I conclude that this limitation of the Part WB is an inconsistency that could confuse new users. Doesn't this inconsistency degrade the effectiveness of Part WB workflows?

Image
Image
Part WB Loft: https://green-candy.osdn.jp/external/fo ... ng_1.FCStd
PartDesign WB Loft: https://green-candy.osdn.jp/external/fo ... n_ok.FCStd

Wouldn't it be a good idea if somebody took a look at that Part Loft programming and made it support hollow lofts aswell? :?:
Jee-Bee
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Re: Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by Jee-Bee »

Hollow objects (at least in PD) are mentioned before... At least by me.
In my ideal world Extrude; Revolve and potentially Loft get a checkbox to add a (uniform)thickness to the feature and (thickness direction).
But as far as i understand there are some difficulties to add this. Some of the difficulties are related to OCCT, but i'm not so deep in that, that i understand how and why.
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quiret
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Re: Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by quiret »

Jee-Bee wrote: Sun Aug 14, 2022 7:11 pm Hollow objects (at least in PD) are mentioned before... At least by me.
In my ideal world Extrude; Revolve and potentially Loft get a checkbox to add a (uniform)thickness to the feature and (thickness direction).
But as far as i understand there are some difficulties to add this. Some of the difficulties are related to OCCT, but i'm not so deep in that, that i understand how and why.
If you mention OCCT as a culprit then I am even more deeply understanding toward the current FreeCAD implementation situation. You guys are fed what you get, eh? And if that OCCT guy ain't giving you then you cannot really improve past it, a strong dependency on the OCCT doing it right.

You mention a possible thickness property for Part WB tools. That could help in many cases, yes. ;) I found a workaround to my situation by use of the 2D offset tool on faces in combination with the Boolean Cut tool. You cut away the innerds of the thing that was done using shrunk faces and you get the hollow thing as result.

I would greatly appreciate if the Loft tool would also work like that using faces instead of wires (as I assume that it currently uses only wires for the calc).
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Re: Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by chrisb »

Part Loft and Sweep are much older than their PartDesign counterparts. So perhaps it may well be possible to augment the Part functions as well?
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Re: Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by Jee-Bee »

If i would create now a loft with a thickness i would do it this way as in the attachment.

Mainly because the thickness on the end is most of the time not the same as the thickness during the loft. I also think that this is faster and more clear as try to do it within the sketcher...
Attachments
test_thickness.FCStd
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quiret
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Re: Part WB Loft vs PartDesign WB Loft - hollow lofts?

Post by quiret »

Jee-Bee wrote: Mon Aug 15, 2022 9:08 am If i would create now a loft with a thickness i would do it this way as in the attachment.

Mainly because the thickness on the end is most of the time not the same as the thickness during the loft. I also think that this is faster and more clear as try to do it within the sketcher...
Thank you for this excellent idea, Jee-Bee! I was unsure how that Thickness tool worked because this relevance of face selection did not imply to me that I could puncture through an object but create a cave. Thus if I select two faces, then I take it that the thickness thing finds its way through the solid? Not quite sure and maybe some YouTube videos with explanations could help me solidify my vision.

The most important part of your attached FreeCAD document appears to be this configuration:

Image
chrisb wrote: Sun Aug 14, 2022 10:34 pm Part Loft and Sweep are much older than their PartDesign counterparts. So perhaps it may well be possible to augment the Part functions as well?
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