error on part design draft feature

About the development of the Part Design module/workbench. PLEASE DO NOT POST HELP REQUESTS HERE!
Jee-Bee
Posts: 1399
Joined: Tue Jun 16, 2015 10:32 am
Location: Netherlands

error on part design draft feature

Postby Jee-Bee » Wed Oct 10, 2018 1:27 pm

I have some comments on the Part design draft feature.
As simple example i created a box. I add a draft on the 4 faces on the sides.
Also a vertical edge as pull direction. I see know a choped off piramid(with a bigger angle...)
When i press ok it complains about not using the neutral plane however the preview works.
So the assumption works great. Could there changed something that if the preview works and the neutral plane is not changed that his assumtion is added as neutral plane?

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14709 (Git)
Build type: Release
Branch: master
Hash: faad5ea27301cb7af393a25d317c406d3098bafe
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: Dutch/Netherlands (nl_NL)
Attachments
draft_feature_with_preview .PNG
draft_feature_with_preview .PNG (30.42 KiB) Viewed 335 times
chrisb
Posts: 11913
Joined: Tue Mar 17, 2015 9:14 am

Re: error on part design draft feature

Postby chrisb » Wed Oct 10, 2018 9:12 pm

I remember this behaviour at least since end of 2017. So it's rather a feature request than an error.
Jee-Bee
Posts: 1399
Joined: Tue Jun 16, 2015 10:32 am
Location: Netherlands

Re: error on part design draft feature

Postby Jee-Bee » Thu Oct 11, 2018 4:24 am

the pop up is a feature request :shock: :?
vocx
Posts: 274
Joined: Thu Oct 18, 2018 9:18 pm

Re: error on part design draft feature

Postby vocx » Sat Oct 20, 2018 10:15 pm

No offense to you @Jee-Bee, but it's hard to understand what you mean because of your English.
  1. Change to PartDesign
  2. Click on "Create body"
  3. Click on "Create an additive primitive" (PartDesign_CompPrimitiveAdditive), or "Additive box", and then OK, just to create a small box
  4. Ctrl+click to select the four side faces of the cube
  5. Then click PartDesign_Draft
  6. The preview will show the pyramid shape (Z_Axis is the implied pull direction). Adjust the angle to 10 degrees to really see the shape, as the original angle is only 1.5 degrees.
  7. When clicking OK, the message "Missing neutral plane" appears.
What you want is that when hitting OK, the feature automatically uses the same implied neutral plane and pull direction that was showing you in the preview.

In general, I don't think this is simple to generalize because PartDesign_Draft should work with different solid objects, not only regular bodies like cubes. For example, I tried many times to replicate this, but at some point it didn't show me the same preview. At some point it tried to pull in the direction of the Y_Axis, instead of the Z_Axis; it also showed me these errors in the Report View.

Code: Select all

Adding face failed on Face3. Omitted
Adding face failed on Face4. Omitted
FreeCad_PartDesign_draft_feature_01.png
FreeCad_PartDesign_draft_feature_01.png (96.88 KiB) Viewed 209 times
The preview pointed to the side, and not up. How is the software supposed to know that you want the draft in the Z direction, and not the other directions? It can guess, but it will not always guess what you want.

I feel that PartDesign_Draft could automatically take the XY_Plane (from the Origin of the Body) as Neutral plane, but ultimately it'd be responsibility of the user selecting the right Neutral plane and Pull direction. Defining the Pull direction automatically is a bit trickier because it really has to be an edge of the Body, it cannot be one of the Body axes.

Interestingly, in this case the Draft works if I only add the XY_Plane as Neutral plane, and leave Pull direction empty. If I add the Z_Axis as Pull direction, it doesn't accept it.
FreeCad_PartDesign_draft_feature_02.png
FreeCad_PartDesign_draft_feature_02.png (99.06 KiB) Viewed 209 times
Jee-Bee
Posts: 1399
Joined: Tue Jun 16, 2015 10:32 am
Location: Netherlands

Re: error on part design draft feature

Postby Jee-Bee » Sun Oct 21, 2018 8:45 am

vocx wrote:
Sat Oct 20, 2018 10:15 pm
What you want is that when hitting OK, the feature automatically uses the same implied neutral plane and pull direction that was showing you in the preview.
yes
vocx wrote:
Sat Oct 20, 2018 10:15 pm
In general, I don't think this is simple to generalize because PartDesign_Draft should work with different solid objects, not only regular bodies like cubes. For example, I tried many times to replicate this, but at some point it didn't show me the same preview. At some point it tried to pull in the direction of the Y_Axis, instead of the Z_Axis...

The preview pointed to the side, and not up. How is the software supposed to know that you want the draft in the Z direction, and not the other directions? It can guess, but it will not always guess what you want.
more or less my point is that if I think the preview is right his assumption is right. If the preview is wrong i try to change it so the preview is what I want.
If no preview FC is unable to cleate one and not enough parameters ale filled or filled wrong...