"BRep_API: command not found" when applying thickness

[malvar]

Hello everyone,

I'm new to Freecad but I'm been learning a great deal ever since I got a 3D printer a few months back. I've been working a project which involves hollowed letters. I'm able to apply thickness of 2-4 mm and higher but only seems to work with letters that have no radii or complex curves. The final piece of my project requires a hollowed letter "B" but unfortunately I get the following error ("BRep_API: command not found") when I apply anything higher than -.6 mm, which is too thin. Can anyone steer me in the right direction and tell me what I may be doing wrong. I'm looking to apply a thickness of at least -2.5 mm.

Any help will be greatly appreciated.

Please see CAD file and error image below.

Thank you.

Details:
Windows 10 Pro
Freecad version: 0.18 and 0.19 (same error on both versions)

[chrisb]

Hi and welcome to the forum!

Thickness is perhaps the function that fails most often in FreeCAD. This come directly from the 3rd party geometric kernel, and there is not much that the FreeCDA developers can do about it. It almost always fails when curved shapes are involved that are controlled by some B-spline, and that's how the curves in most fonts are defined, by Bezier curves, which are a subset of B-splines.

In short: Try thickness; if it works - good. If it fails - don't invest time. In the worst case you have to invest quite some time to remodel the inner part for subtraction.

[chrisb]

Here is the best I can do for you: I used a sweep to get a thicker wall. Please note that the sweep does not pass the Part geometry check, which means that problems can occur if you use such object in further operations, e.g. booleans. So I wasn't able to make a union of the wall with the bottom.

Snip macro screenshot-fc99d4.png (10.84 KiB) Viewed 848 times

[malvar]

Chris,

I really appreciate you taking the time to help me, you're awesome, thank you. I downloaded your file but I think it's missing the walls for some reason. Also would it be possible to also add the walls to the openings inside the letter shown on the image below? Thank you again.

[chrisb]

I will look into it later when I am back at my computer. Meanwhile you can add your full FreeCAD infos. I am afraid it is an OCC issue.

[UR_]

Another B

Screenshot 001.png (10.35 KiB) Viewed 727 times

Screenshot 002.png (14.91 KiB) Viewed 727 times

file:

AnotherB.FCStd

(89.96 KiB) Downloaded 20 times

version:
OS: Windows 10 (10.0)
Word size of FreeCAD: 64-bit
Version: 0.20.24847 (Git)
Build type: Release
Branch: master
Hash: 20e756306d9aa624fcbf465f0345d721673ce720
Python version: 3.9.2
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.1
Locale: German/Germany (de_DE)

[chrisb]

I use

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.24825 (Git)
Build type: Release
Branch: master
Hash: ccc4151b3020969450325466e385850783795325
Python version: 3.9.2
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.1
Locale: C/Default (C)

You could try the sweep yourself with this section and the outer edges as path. The inner walls could be done the same way.

SnipScreenshot-ee19ae.png (17.54 KiB) Viewed 722 times

[chrisb]

UR_'s approach is probably the better solution. It doesn't show errors on geometry check.

[malvar]

Thank you Chris, UR_'s method may be the way to go.

UR_ Can you please shoot me some quick steps as to how you added the walls to your B. I've been playing around with your file for a few hours now and can't figure it out. I need to create the walls on the back side of the B like in my original file. I successfully thickened the walls and made them taller but I was not able to move them to the back side of the B. Thank you for your help.

[UR_]

... but I was not able to move them to the back side of the B ...

Please have a look at extrude's properties editor.

Screenshot 001.png (7.86 KiB) Viewed 581 times