Repositioned item reverts to original position when making union

[Cered]

I have three pieces which I am trying to join together to make an assembly. I can position two of the pieces correctly and then in the Part workbench I make a union of these with success. Now if I try to use the same procedure to position and join a third piece to these two then as soon as I click the tool to 'Make a union of several shapes' I find that the third piece repositions itself to it's original position and does not join. Is there a way of locking the piece that I move before I attempt the join?

[TheMarkster]

I'm unable to reproduce this behavior with the version I'm using.

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.25306 (Git)
Build type: Release
Branch: master
Hash: 5f5b3d9b67136edda1f6738f1a83154990f7839d
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)

[chrisb]

Upload a file we can investigate. And note that the union is a new object with its own placement.

[Cered]

Sorry, I omitted my details.
Using windows 10 on desktop. Using FreeCad 0.19 I'm not sure how to find any additional information.

[chrisb]

Using FreeCad 0.19 I'm not sure how to find any additional information.

You find how to attach your full FreeCAD info in the IMPORTANT forum rules linked above.

[Cered]

Sorry chrisb
Can't seem to locate the about freecad page and my last reply did not seem to submit successfully. I think I must be needing to get to my bed so I'll have another look tomorrow.

[chrisb]

Can't seem to locate the about freecad page and my last reply did not seem to submit successfully.

Here is a detailed description: Std About.

[Cered]

Hi all again,
After a good nights sleep everything is now making a lot more sense. So here's the information which, I've no doubt, you experts will find useful if not essential.

OS: Windows 10 Version 2004
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.6+
Qt version: 5.15.1
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/United Kingdom (en_GB)

I'll attach one of the files where an object moved to the desired position ready to make a final union would immediately revert to it's original position when the 'Make a union' tool was selected.
Well, isn't that interesting! If I open that file this morning it seems that it has made the union of the parts overnight so I now have my assembly completed and ready for the next stage with the 3D printer.
Thanks to you all for your help particularly chrisb who has directed me to TheMarkster and his well made and easy to follow videos of numerous FreeCad projects.

[papyblaise]

To sleep better the next few nights, accept some good advice for beginners
If the end is to have a unique piece, draw everything in one body
rather than moving the body002, change the position of the sketch (3mm to the left in X), and Pad = Reverse (if you ignore the 1st advice)

[TheMarkster]

When using a Part workbench tool with Part Design objects you should only reference the Body and not the internal features of that Body. Easiest way to do that is to select the 2 bodies to be fused in the tree (rather than in the 3d view), and then use the Part union tool. This avoids out of scope warnings in the report view and red arrows in the dependency graph.