Part Design workbench - pocket involute gear

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mjanoska
Posts: 1
Joined: Sat Jan 15, 2022 10:46 pm

Part Design workbench - pocket involute gear

Post by mjanoska »

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: English/United States (en_US)

Using the part design workbench.
I am having some trouble pocketing an involute gear with an offset version of itself to make it partially hollow and then exporting as a STEP. I seem to be able to create the model in freecad but then when it exports to step there appears to be a problem.

I was not able to create an involute gear using the part design thickness tool - when trying to do this with an inward thickness it failed.

I then moved on to use the part workbench and used the 2-d offset tool to create a smaller version of the gear outline, add this back to the part design model as a shape binder and then used this as the source to pocket the gear - see enclosed file.

This appears to work.

However when I then exported to a STEP file I get the following error.

18:04:19 Traceback (most recent call last):
File "<string>", line 4, in <module>
<class 'OSError'>: Cannot open file 'C:/Users/mjano/Desktop/gear pocket.step'

The file is still output (or partially output) but the pocket would not render - step file enclosed.

Questions:

1 - Can I do this using the part design workbench only rather than a combo of the part design and part work benches
2 - what am I doing to cause the step export to fail

thanks
Mark
chrisb
Veteran
Posts: 53922
Joined: Tue Mar 17, 2015 9:14 am

Re: Part Design workbench - pocket involute gear

Post by chrisb »

Hi and welcome to the forum!

I would do the cut in Part workbench.

Please retry the step export in 0.20.
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TheMarkster
Veteran
Posts: 5505
Joined: Thu Apr 05, 2018 1:53 am

Re: Part Design workbench - pocket involute gear

Post by TheMarkster »

mjanoska wrote: Sat Jan 15, 2022 11:06 pm
OCC version: 7.5.0
I believe this to be the version of OCC with the step export bug.
domad
Veteran
Posts: 2053
Joined: Mon Jun 22, 2020 12:16 pm

Re: Part Design workbench - pocket involute gear

Post by domad »

mjanoska wrote: Sat Jan 15, 2022 11:06 pm ......
Hi mjanoska, greetings to the Community!

Here is an example of how it can be done, note that the offset dimension must be feasible, that is, achievable otherwise it will generate an error and the object will disappear from the view.
The animated * .gif show the flows for the external and internal offset.
In the * .gif for the internal offset there are two inconsistencies that generate the most common errors: for example, a missing connection and several unverified coincidences; it is also shown how to intervene, in this case, to correct these inconsistencies.
Attachments
Profile_gear_offset_int.FCStd
(734.61 KiB) Downloaded 12 times
Profile_gear_offset_ext.FCStd
(744.51 KiB) Downloaded 11 times
Profile_gear_ext_offset.gif
Profile_gear_ext_offset.gif (922.06 KiB) Viewed 495 times
Profile_gear_int_offset.gif
Profile_gear_int_offset.gif (1011.52 KiB) Viewed 495 times
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