drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

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csteckel
Posts: 1
Joined: Sat Nov 27, 2021 9:37 am

drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by csteckel »

Hi all,

FreeCad is an amazing piece of software. Thanks to everyone involved.

I am trying to produce a single letter e.g. B to be hollow and open on the front. My first approach was
1) in Draft WB: Use "create shape from text", select Arial font, give it a letter B.
2) Part WB: pad/extrude the ShapeString.
3) Part WB: use "thickness" tool to give the B a thickness on its back and side walls. open in the front. select the front and open the thickness tool.
and from here it gets wonky. I have tried all modes, join types and intersect, self-intersect options. The results are all not expected and essential throws errors.
approach_1.PNG
approach_1.PNG (46.72 KiB) Viewed 1147 times
Second approach:
1) in Draft WB: Use "create shape from text", select Arial font, give it a letter B.
2) PartDesign WB: add empty body with extruded ShapeString; use "make a thick solid".
same wonky results as for the first approach.
approach_2.PNG
approach_2.PNG (114.26 KiB) Viewed 1147 times
Third approach:
1) in Draft WB: Use "create shape from text", select Arial font, give it a letter B.
2) in Draft WB: try give the ShapeString an any offset (preferably a negative one) to produce a copy.
3) in Part WB: pad/extrude both ShapeStrings and then execute the boolean operations to hollow out the letter
failed in step 2 when trying to offset the letter:

Code: Select all

10:57:37  Traceback (most recent call last):
  File "C:\tools\FreeCAD-0.19.2.7b5e18a-WIN-x64-portable1\Mod\Draft\draftutils\todo.py", line 167, in doTasks
    Gui.doCommand(string)
  File "<string>", line 1, in <module>
  File "C:\tools\FreeCAD-0.19.2.7b5e18a-WIN-x64-portable1\Mod\Draft\draftfunctions\offset.py", line 130, in offset
    if DraftGeomUtils.hasCurves(newwire) and copy:
  File "C:\tools\FreeCAD-0.19.2.7b5e18a-WIN-x64-portable1\Mod\Draft\draftgeoutils\general.py", line 134, in hasCurves
    for e in shape.Edges:
AttributeError: 'NoneType' object has no attribute 'Edges'
I do not want to PartDesign a letter from raw elements as the goal is to produce all letters of the alphabet in different fonts and size and the cnc them from wood to have molds... I have tried different simpler letters e.g. T with no holes and curves. but the same wonkiness happend.

thanks for any hints. do I have to pre or postprocess the ShapeString in step 1 and then all is good? Ih ave played around with the Draft WB upgrade and downgrade. but no luck.

Carsten

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: German/Germany (de_DE)
Attachments
offset_a_letter.FCStd
(13.18 KiB) Downloaded 23 times
chrisb
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Re: drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by chrisb »

Hi and welcome to the forum!

Thickness is one of the most picky functions in FreeCAD - or better in the third party geometric OCC kernel. This question comes up from time to time and it is not finally solved yet. You can play with 2D- or 3D-offset in Part workbench or perhaps can addon Curves workbench help you further.
I wonder why the T fails, because it is usually the B-spline curves which cause thickness to fail.
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Willem
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Location: Lisse, The Netherlands

Re: drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by Willem »

In Draft workbench convert a copy of Shapestring to sketch.
Delete the inside
Extrude the sketch in Part workbench,
Make a boolean in Part workbench of the 2 extrudes
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papyblaise
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Location: France

Re: drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by papyblaise »

I transform the B into a sketch, use the Arch workshop (hey yes) and mount a wall 0.5mm 5mm high
Attachments
B.PNG
B.PNG (28.97 KiB) Viewed 1063 times
B.FCStd
(34.75 KiB) Downloaded 24 times
TheMarkster
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Re: drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by TheMarkster »

In Part workbench use 2D offset tool on the shapestring. Extrude both the shapestring and the offset and use one of the extrude objects to cut from the other. Place the cutting tool up in the z direction so the back wall remains.
Snip macro screenshot-00d00d.png
Snip macro screenshot-00d00d.png (68.24 KiB) Viewed 1033 times
Unfortunately, this file fails check geometry with bopcheck enabled. It might not matter with this particular error.
Attachments
b.FCStd
(71.86 KiB) Downloaded 26 times
domad
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Joined: Mon Jun 22, 2020 12:16 pm

Re: drafted shape from string "letter of alphabet" does not allow an offset or thick solid or thickness operation

Post by domad »

Greetings to the Community!
The "Create Thickness" tool of the "Part" Workbench, in this case, works without problems for positive thicknesses (towards the outside), but when you try to create the thickness towards the inside, it works limited to a certain thickness depending on the size of the letter (hollow face), is documented in the * .gif
Attachments
offset_a_letter.gif
offset_a_letter.gif (983.07 KiB) Viewed 1019 times
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