FreeCAD Forum

Hello all, I wonder if anybody can help:

I am creating bolt through holes with counterbores in the base of an object. This means creating two pockets. I tried creating two pockets based on the same sketch (the sketch had concentric circles), this was unsuccessful. So I created two sketches on the same face: One 3mm diameter padded to 1.6 mm depth, the height of the bolt heads, and the other 1.6 mm diameter and padded through the object. On both sketches, holes are fully constrained by symmetry and from edges. However, when I add the second sketch, the first one loses constraints to edges.

The file should be attached. The two relevant sketches are under pocket008 and pocket010.

Also, overlapping ghosts of prior hole placements seem to remain. They are visible in the initial view in the attached file.

There were no error messages.

Many thanks for any kind advice.

Best regards, Paul

Create a sketch with one or more circles. The circles define only the center point of the hole. Close the sketch.

Then select the ske8in the the tree view and us ethe Hole tool. In the hole tool dialog select the bolt size etc. and selected the counterbore. option. Click ok, and the bolt holesmwill be created at the center points of the sketch.

https://wiki.freecadweb.org/PartDesign_Hole

You've been hit by the topological naming problem - making external references to edges that can change names and attaching sketches to faces that can change names.

I attached your last two sketches to the XY-Plane and offset them by -Pad.Length This is stable. I changed the external references in the sketches to lines in the sketches that created them. Unless you change the geometry of the sketches, this is stable.
https://wiki.freecadweb.org/Topological_naming_problem

Dear Ed,
Thanks so much for your kind help. You are right, it seems a topological naming problem. On your solution,, the sketch under Pocket008 is now not fully constrained, I guess because there is no external geometry (no 'edges linked to external geometry') on the sketch any more. I wonder whether you may have any insights into this. I have no idea how I would create constraints: Previously when selecting external geometry I simply picked lines that successfully highlighted.

I read the wiki on the topological naming problem, but was not clear whether, if I subsequently rename sketches the problem could reappear.

By the way, according to forum rules I should probably say I am using v0.19.

Thanks a lot!

Best regards, Paul

edwilliams16 wrote: ↑Wed Jun 29, 2022 11:41 pm You've been hit by the topological naming problem - making external references to edges that can change names and attaching sketches to faces that can change names.

I attached your last two sketches to the XY-Plane and offset them by -Pad.Length This is stable. I changed the external references in the sketches to lines in the sketches that created them. Unless you change the geometry of the sketches, this is stable.
https://wiki.freecadweb.org/Topological_naming_problem

You can rename sketches to which you make external references - no problem. but if you go back and decide your base sketch should be hexagonal rather than square, you will almost certainly have to go through and redo your external references. You change dimensions no problem.

As to your sketches, I hadn't noticed you were pocketing two identical sketches. I'm not sure of your design intent, but one would suffice. Had you needed to pocket both up and down, you would use the two dimensions option.

Re version information, what is wanted is

Open the Help --> About FreeCAD menu then click on the "Copy to clipboard" button, and paste its content in the text input area. This will provide us valuable information on your exact version and revision number, your operating system as well as FreeCAD's internal libraries. (Mac users: the About FreeCAD menu is under the FreeCAD menu.)
Please do not attach a screen capture instead of posting the Help > About FreeCAD information from the clipboard. Don't add your FreeCAD info or any other version data to your signature. When you change your signature, the forum software shows the updated signature in every post you ever made, obviously this means that over time your version data in a signature would become wrong for all your previous posts.

Dear dmacro,
Keeping just one sketch and using the hole function: I think that may have fixed it. Many thanks for your help!

Best regards,
Paul

drmacro wrote: ↑Wed Jun 29, 2022 11:14 pm Create a sketch with one or more circles. The circles define only the center point of the hole. Close the sketch.

Then select the ske8in the the tree view and us ethe Hole tool. In the hole tool dialog select the bolt size etc. and selected the counterbore. option. Click ok, and the bolt holesmwill be created at the center points of the sketch.

https://wiki.freecadweb.org/PartDesign_Hole

Dear Shalmeneser,
Thanks for your help, though it appears to have become a unibody and the design was for a multi-part.

Best regards Paul

Shalmeneser wrote: ↑Thu Jun 30, 2022 9:43 am

pgershon wrote: ↑Fri Jul 01, 2022 2:06 am ... though it appears to have become a unibody and the design was for a multi-part.

ONE body = ONE object (from your own file)

If you want different parts, you need to have different bodies.