Grouping in FreeCad 0.20

[pgershon]

Hello FreeCad people,
Its time, I think, to learn a little more about the quirks of FreeCad 0.20 29177 )6/13/2022)

With the very kind help of folks here, I had generated, I think, a reasonable model that was essentially finished (Stage-Test10, attached). It appears that, with kind help, I have conquered the topological naming problem for a moderately complex model. But I still want to tinker with the design a bit.

For example, I decided to extend one pad ("Pad-block4") by an additional 1 mm in the reverse direction, and I noticed some pockets had now become opaque (filled). The result of this single modification is shown in the file "Stage-Test11", attached.

So to try to isolate the issue by viewing individual objects (Block2, Block1, Block3, Block4, Block5) I decided to try the simplest thing according to all the videos I have seen: Toggle things on and off with the space bar. It did not work like in the movies: Toggling individual rows of the tree (under "Body") on and off causes all kinds of bizarre and apparently random bits of the overall model to appear and disappear. I guessed this may be because I have no proper hierarchy in the tree,

OK, so I thought it was therefore time to take it to the next level: Start to develop a hierarchy by creating a group for each "Block". But every time I go to the "Create Group" icon it creates a new group OUTSIDE the body. So I look at a few videos, and everyone just either creates a group within the body without issue, or there is a "Create group" option in the right-click dropdown when on a row of the tree, and it successfully creates a group below that point in the tree. But I don't see this option in my right click menu. At this point, I figure I have gone right off the rails, and I wonder if somebody here might be kind enough to point me in the right direction.

Many thanks and best regards, Paul

[Bance]

User error, the tree can be thought of as a time line, if the visibility is changed it is akin to going to an earlier stage in the modelling process.(I.E. before the pockets are made.)

The small green mark on the feature represents the 'tip' this is the state of the model as seen by the rest of FC, and is the actual state of the model.

Change the visibility to this and the pockets magically reappear.

[Bance]

The process of changing visibility from the top of the tree down in turn, is the method to analyse how the model was built, stage by stage.

The 'tip' also allows one to temporarily reset the condition of the model, such that features can be added prior to others. A case for this might be to move a feature so that it can be added to a feature pattern.

[Shalmeneser]

DatumPlane BottomFace-Block3 should have z=-9.525 and not -9.52 (holes are not opened).
You can use this expression for z :

Code: Select all

-<<Pad_Block2_CamHole>>.Length / 2 - <<Sketch_Block3>>.Constraints[17] 

You should use expression for every logic repetition :
<<Sketch_Block3>>.Constraints[17] should be <<Pad_Block2_CamHole>>.Length and not 6.35

If you modify 6.35 in the 1st pad, the construction will follow ? Not in your file !

Do not pocket twice the same hole but use Hole tool with flat drill point and Counterbore.

[pgershon]

Shalmeneser,
Thanks for all the good advice.

I tried changing DatumPlane BottomFace-Block3 from z=-9.52 to -9.525, and got a red exclamation point adjancent to "Pocket_Block3_Slot. So I changed it back.

Best regards, Paul

[pgershon]

Overal,
Thanks guys for your excellent advice, there was a serious dose of user ignorance regarding the green tip and timeline. However, if grouping of objects is potentially beneficial in turning individual "blocks" on and off, in my tree, I would still be curious how to get a new group to fit under "Body" in the hierarchy. Sorry if this is obvious, but when I looked at:

wiki.freecadweb.org/Assembly3_GroupObjects

I noticed the documentation was unfinished, which prompted my question initially. Related questions in the forum seemed to be with older versions of FreeCad.

Thanks again and best regards, Paul

[Bance]

You did not mention Assembly in the OP.

To get good answers one needs to ask good questions. Failing that FC info may have shed a light, but that was absent also.

Finally Assembly3 questions are best asked in the Toponaming and Linkstage forum

[pgershon]

I can't quite fully understand what you wrote, e.g. what is an "OP".

The link I gave was simply the top hit in a google search for "freecad group objects". Google chose it.

I thought I had originally asked whether grouping would be beneficial in the example file that I had given, and why a created group was only appearing at the top level of the tree, and not appearing below the active (selected) line in the tree.

It does not appear to be answered at this link either:

https://wiki.freecadweb.org/Std_Group

I got that link by typing "group" in the search box of freecad wiki.

Anyway, I guess the definitive answer to these questions are that they are not good questions and the logical outcome, therefore, is that there is no good answer, assuming I follow your line of reasoning correctly. Maybe groups can only be created within groups, not within a body, is that the answer?

Thanks, Paul

[Bance]

OP is forum speak for Original Post.

There is no concept of groups in a body, other than the body itself.

Perhaps you could point out one or two videos that describe this behavior.

As I explained earlier, the disappearing features are a consequence of effectively going back in history when changing visibility in the tree structure.

Think of the PD body as a piece of modelling clay, you can add to it or take from it, but it always remains a single solid.

The features in the tree are not unique objects, they are homogeneous to the whole, because they have been booleaned together (this is abstracted from the user in PD WB.)

They therefore cannot be grouped. The order in which they are created has a direct effect on the outcome.

[pgershon]

@Bance:
Thanks. I am just returning to this now, many weeks later after many distractions, but freecad has been working well for me and I am getting to know it. I like it.

You asked a question about videos I had watched:

Previously I had done a DuckDuckGo search "freecad group objects". My history shows I viewed the following video from that search:

https://www.youtube.com/watch?v=pdm-GUvisJo

Best regards and thanks again, Paul