Oval loft?

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Giterdun
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Joined: Sat Feb 13, 2021 5:34 am

Oval loft?

Post by Giterdun »

I'm trying to make hollow object using two ovals to try and understand how to use the loft. I can make the shape I want with the loft, but when it is sliced in the 3D printer software to print, it shows up as a solid. In FreeCAD it looks normal, but also gives a bunch of "links go out of allowed space" errors.. I can't figure out why it's showing solid in the print preview, and I don't understand the errors... see attached pics and FCstd file.. I would appreciate if someone could shed some light on why this is happening.. I've looked in documentation and around here, but I can't find a similar issue.. Thanks..
Attachments
Oval Loft1.png
Oval Loft1.png (172.4 KiB) Viewed 1748 times
Oval Loft.png
Oval Loft.png (113.02 KiB) Viewed 1748 times
Oval Loft.FCStd
(13.57 KiB) Downloaded 26 times
TheMarkster
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Re: Oval loft?

Post by TheMarkster »

The Links out of scope warnings are because you are using Part::Loft and the sketches are inside a PartDesign::Body. You should use PartDesign::Loft instead if you don't want those warnings. (The warnings can be ignored in this case unless you move the Body, in which case the Loft will not be positioned correctly, but regardless of that you should strive to avoid these warnings.)

For the other issue, not being a solid, you need to toggle the Solid property of the Loft object to True. There is a checkbox in the dialog for this purpose, too.

Suggestion:

Delete the Loft
Select both sketches and in the Part Design workbench, click the Loft Tool. Press OK in the dialog. Done.
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Giterdun
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Re: Oval loft?

Post by Giterdun »

TheMarkster wrote: Thu Oct 21, 2021 3:14 am The Links out of scope warnings are because you are using Part::Loft and the sketches are inside a PartDesign::Body. You should use PartDesign::Loft instead if you don't want those warnings. (The warnings can be ignored in this case unless you move the Body, in which case the Loft will not be positioned correctly, but regardless of that you should strive to avoid these warnings.)

For the other issue, not being a solid, you need to toggle the Solid property of the Loft object to True. There is a checkbox in the dialog for this purpose, too.

Suggestion:

Delete the Loft
Select both sketches and in the Part Design workbench, click the Loft Tool. Press OK in the dialog. Done.
Ok thank you.. not sure if you misunderstood, but I don't want it to be a solid.. I just want the walls around it, like it is shown in the Freecad file.. so I'm confused why I would toggle the Solid property.. .. I thought I tried Loft in PartDesign as well, but will have another look at that.. thanks again..
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Willem
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Re: Oval loft?

Post by Willem »

If you do not want a solid create the sketches not in Part Design but with the Sketcher workbench.
You can pick the sketches with the mouse and drag them out the Body
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Shalmeneser
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Re: Oval loft?

Post by Shalmeneser »

You should not use zero dimension. (use Sketcher_ConstrainPointOnObject here, or offset the sketch.)
TheMarkster
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Re: Oval loft?

Post by TheMarkster »

Giterdun wrote: Thu Oct 21, 2021 5:09 am
Ok thank you.. not sure if you misunderstood, but I don't want it to be a solid.. I just want the walls around it, like it is shown in the Freecad file.. so I'm confused why I would toggle the Solid property.. .. I thought I tried Loft in PartDesign as well, but will have another look at that.. thanks again..
The walls of a shell are like points in geometry, they have no thickness. How thick do you expect the 3D printer to make the walls when they have no thickness and thus no dimension for the software to follow? 1mm? 0.1mm? 0.001mm? You do want a solid, whether you know it or not. Make the Solid in Part Design, and then use the thickness tool. Select the top and bottom faces, apply the thickness inwards to whatever you want the wall thickness to be.
Snip macro screenshot-1cdf25.png
Snip macro screenshot-1cdf25.png (49.19 KiB) Viewed 1511 times
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Giterdun
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Re: Oval loft?

Post by Giterdun »

Willem wrote: Thu Oct 21, 2021 5:58 am If you do not want a solid create the sketches not in Part Design but with the Sketcher workbench.
You can pick the sketches with the mouse and drag them out the Body
Thanks.. not sure I totally understand what you mean, but I'll try to look at that.. ;)
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Giterdun
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Re: Oval loft?

Post by Giterdun »

TheMarkster wrote: Thu Oct 21, 2021 3:22 pm
Giterdun wrote: Thu Oct 21, 2021 5:09 am
Ok thank you.. not sure if you misunderstood, but I don't want it to be a solid.. I just want the walls around it, like it is shown in the Freecad file.. so I'm confused why I would toggle the Solid property.. .. I thought I tried Loft in PartDesign as well, but will have another look at that.. thanks again..
The walls of a shell are like points in geometry, they have no thickness. How thick do you expect the 3D printer to make the walls when they have no thickness and thus no dimension for the software to follow? 1mm? 0.1mm? 0.001mm? You do want a solid, whether you know it or not. Make the Solid in Part Design, and then use the thickness tool. Select the top and bottom faces, apply the thickness inwards to whatever you want the wall thickness to be.

Snip macro screenshot-1cdf25.png
Thank you for the explanation.. I was not aware that it had to be solid and then use the thickness tool.. I simply drew the 2 ovals, spaced them about 10mm apart, and used the loft tool to create the object in the pic. I guess I incorrectly assumed that because it created that object, that it had some kind of a thickness... So I will redo that and use the thickness tool as you say.. first I gotta find it.. lol.. I've never used that tool before, but I will give it a try for sure. I'll post back on how it turns out.. Thanks again..
TheMarkster
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Re: Oval loft?

Post by TheMarkster »

An alternative to using thickness (which is prone to failure) is you could add the walls to the sketches by having a smaller version of the oval inside the other, and then loft. (But Part::Loft cannot deal with internal wires, so you need PartDesign::Loft for that.) With Part::Loft you would need to do 2 lofts and cut the inner from the outer.
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Giterdun
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Re: Oval loft?

Post by Giterdun »

TheMarkster wrote: Thu Oct 21, 2021 4:42 pm An alternative to using thickness (which is prone to failure) is you could add the walls to the sketches by having a smaller version of the oval inside the other, and then loft. (But Part::Loft cannot deal with internal wires, so you need PartDesign::Loft for that.) With Part::Loft you would need to do 2 lofts and cut the inner from the outer.
lol.. strange you say that.. it worked a couple times for me when I tried like you mentioned in the previous post.. I dunno what happened, but now, no matter what I do, I keep getting this thickness error (see attached).. I even closed the file, shut down and restarted Freecad a number of times, but now it always happens.. I have no idea why it started doing that out of the blue or how to fix it.. :x

so to do as you say here, I would have to make 1 inside and 1 outside ovals for each of the ovals to make the wall thickness?? I'll play around with that and see if I can get it to work.
Thanks again..
Attachments
Thickness error.png
Thickness error.png (95.19 KiB) Viewed 1394 times
loft.png
loft.png (75.26 KiB) Viewed 1394 times
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