[Solved] "Ruled Surface -> Normal to Surface" function

[troyp76]

Hello,

I am attempting to model how a square tube would be cut by a 4 axis laser cutting machine, particularly the corners of the section highlighted in red below.

screenshot.png (50.12 KiB) Viewed 1025 times

My research suggests this would be achieved in other CAD packages using a "Ruled Surface -> Normal to Surface" function to define the surface that is then used to cut the original profile.

Is there an equivalent function within FreeCAD or the Curves WB that could be used in a similar way?

Thanks

OS: Windows 10 Version 1909
Word size of FreeCAD: 64-bit
Version: 0.20.25177 (Git)
Build type: Release
Branch: master
Hash: f8c65989f9b076f4f63f31fd83d1e9e7b34fdac1
Python version: 3.8.6+
Qt version: 5.15.1
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/Australia (en_AU)

[Cekuhnen]

I dont follow - the screenshot is what you have modeled already ?

Could you zoom and better show what you would like to model ?

[GeneFC]

My research suggests this would be achieved in other CAD packages using a "Ruled Surface -> Normal to Surface" function to define the surface that is then used to cut the original profile.

Is there an equivalent function within FreeCAD or the Curves WB that could be used in a similar way?

I don't understand what you have highlighted. Are you trying to cut the entire shape or are you concerned only with the top (circled) edges?

In any case the FreeCAD functionality for creating cutting paths is in the Path Workbench. This shape looks very straightforward to cut from the front side.

Gene

[Bance]

He's using a 4 axis machine to make the cuts, that means the corners have a particular profile (Twisted?)

I believe that is what is required.

[troyp76]

Thanks for the replies, re-reading my post after a nights sleep I can see it could have been clearer.

Bance was on the right track, I am trying to model weldments to be cut on a tube cutting machine using a commercial Tube cutting CAM package.
My goal is to visualise the actual cut to check clearances etc.

I found this example of how it can be done for pipes in Solidworks.
SOLIDWORKS - Creating a Coped Cut Perpendicular to a Pipe

Working on it more tonight I have found a way to manually achieve a similar effect as the "Ruled Surface -> Normal to Surface" in the video.

I used the Face Normal function in the Work Features Macro WB to manually place the normal lines around the corner.
Then creating ruled surfaces between each line to create the surface to cut the main body as shown in the GIF below.

coping cut.gif (921.22 KiB) Viewed 875 times

I can see now that the creation of the normal lines along the corner edge could be done with some macro programming.
Also assume that the lines could be used to create rails for the Curves WB swept surface tool.

Before going down this path, I am still wondering if there is an another approach that I may have missed?

Cheers,

Troy

[troyp76]

Replaced the ruled surfaces with a gordon surface and it is looking a lot better.

Just need to work out how to avoid the manual normal placements now.

gordon_surface.gif (811.15 KiB) Viewed 839 times

[troyp76]

Seems I just needed more time to find a simpler solution. I will edit the title of the post to indicate that it is solved.

In case it is useful to anyone else out there, the key steps I took are:

- A sketched line parallel to the tube corner radius located at the center of the arc.
- Part-> Ruled Surface between this line and the curved profile of the tube corner.
- Surface WB -> Extend Face to extend the ruled surface past the tube profile to be cut.
- Connect the new faces as a compound and then use Part->Split->Slice Apart to cut this surface from the main tube profile.


NOTE: in the GIF I did this for both corners and also a similar approach for the flat top of the tube profile.

ruled_surface.gif (1009.56 KiB) Viewed 729 times