Help! Can't get Draft Array to work

[sozoplamo]

Hi,
I am pretty new to freecad and I am just trying out the draft array function.
I am trying to build a caterpillar track using draft array but I can't seem to get it to follow the path.
I get a very exploded view even when i try to get the individual tract link to align with the path. Moreover it seemed to be offset from the path.
My version is 0.19, Windows 64bit and the print screen and file are attached as per follows.
Would appreciate if any of the gurus here could provide me a tip or 2!!!
Regards,
Jeremy

[Willem]

Welcome to the forum.
There are tutorials for this,
https://forum.freecadweb.org/viewtopic.php?t=18267
https://www.youtube.com/watch?v=Wm9cD6SWyRs

[chrisb]

Hi and welcome to the forum!

It works here if I delete and recreate the PathArray. So it may depend on your version.

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)

But there are more problems in your model: You have main planes outside of a body and reference them from inside. Look at the dependency graph to get this sorted.
For my taste an absolute no go is the way you renamed the sketches: Sketch117 has the label Sketch118, Sketch117 has the label Sketch116. What is your intention with these horrible names?

[sozoplamo]

Hi and welcome to the forum!

It works here if I delete and recreate the PathArray. So it may depend on your version.

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)

But there are more problems in your model: You have main planes outside of a body and reference them from inside. Look at the dependency graph to get this sorted.
For my taste an absolute no go is the way you renamed the sketches: Sketch117 has the label Sketch118, Sketch117 has the label Sketch116. What is your intention with these horrible names?

Hi Chris,
I mapped the track path from another body and created the tracks in the second body. Deleted the first body after that, which explains why I have weird sketch names.

Thanks for the tutorials! I will try them out at the next possible opportunity!

OS: Windows 10 Version 2004
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/Singapore (en_SG)

[sozoplamo]

Thanks for the tips guys!
I managed to get the draft array working, but the curves seems misaligned.
Anyway for me to get this working?

OS: Windows 10 Version 2004
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/Singapore (en_SG)

[Roy_043]

The source object needs to be properly aligned to get a better result. I have transformed (Std_TransformManip) the Body by eye, and then I have nested it in a Std_Part. The Part is in the default position, that is important. Of course I have also 'unnested' the path object from the Body. Note that the result will never be 100% accurate.

[chrisb]

Results are usually best (though not exact, see Roy's comment) if you place the middle of the two rotation points in the center. In this case you should have aligned the whole object around the center of the coordinate system.

[chrisb]

I managed to get the draft array working

What did you finally change to make the wildly splattered PathArray into a chain?

[sozoplamo]

I managed to get the draft array working

What did you finally change to make the wildly splattered PathArray into a chain?

Hi Chris,
I deleted the sketch and drew it again.
Edited the pad to the origins as well which arranged it pretty decently albeit a little misaligned on the radius.
I further edited it by using Roy's comment and placed the origin smack in the center of the pad which arranged it really well!
One small obstacle I had, was that I tried to attach it into assembly 4, but it couldnt see it as a body. I ended up doing a work around by saving it as a step file and manually arranging it as I cant get the coordinate system out. Worked out pretty well though.