Unable to use Project Geometry where I need it to

[nima360s]

As an extra assignment for my CAD course I need to project some circles (dots of a lego piece) to the cavity on the underside on the piece so that I can then add some "hooks" I am posting the full translated task with pictures. 

All that is given is a list of tips and a drawing.

- Use project geometry in order to project geometries you are unable to reach in the sketch mode

- Snap the lower cavity in the center of the dot to the lego piece's top. Observe, because the dot is on the other side of the lego piece it will not show in your sketch. Therefore, rotate the lego piece so that you are able to see the dots, press project geometry and then on the dot. Rotate back and you will be able to see a yellow circle being projected to your sketch. You can now snap the circle for the lower cavity in the center of the projected circle

[YannickEnrico]

If I understand the task correctly, you need to create a sketch on this inner surface, and use the button "Project Geometry" on the circles outside (you can actually reach them through the part of you hover your mouse carefully)

The assignment is teaching you to reference other geometry, and you can do that via project geometry.

[CCarreiras · Accepted solution]

Hi!

It will something like this:

 Of course you can do all 4 at once, using the same sketch and the same extrusion.

[nima360s]

Thank you, I see now that the problem was I was trying to use project geometry after choosing the top instead of the cavity. 

[nima360s]

If it is okay that I ask more questions, as you can see in the blueprint I need to make ridges aligned with the dots. I am able to create them but only find how to snap the corner to the middle of the dot, which makes the ridges misaligned. I need to know how to center them. 

[CCarreiras]

Keep projecting geometry from solids or other sketches to use as reference in the present sketch:

[CCarreiras]

Tip:

If you design the inicial square centred with the origin planes, you just have to create 1/4 of the features, then just mirror them using the origin planes as the final in the previous video.

[nima360s]

When I try to mirror i see a projection of another legoblock outside my project. The mirrored pillar ends up outside instead.

[CCarreiras]

As i said... "if you design the inicial square centered with the origin planes".
And that's why one of the basic "rules" is to design the parts centred with the origin planes.

Probably you didnt design the part centred, and that's why the mirror lays outside the part.
In that case you need to add auxiliary planes to use mirror.

If you place here the part, we can show you...

[nima360s]

I apologize, in my textbook we were told to use the centerpoint as a corner. Probably a bit easier for a complete newbie.

I have moved the body so that it is over the centerpoint, but it still seems like it wants to mirror outside.

It seems like the move body function only moves the 3d image not the actual sketches etc as it highlights outside the red piece

[CCarreiras]

Usually, moving the body is used at the end of the modeling (or near the end) to move the complete body to a new position.

Moving the body will not work in this case to do that mirror, because all operations occur before the moving.

The correct way to do it is, edit the first sketch and place the geometry centred.
All the model will adjust (sometimes with small fix/adjustements).

[nima360s]

I'm so sorry for all the headache.

I have tried experimenting and using chatgpt but I can't find a way to move it so that CP is in the exact center. 

Teacher only said "the answer is in the textbook" but moving and placement has not been touched upon at all. 

[YannickEnrico]

Enter the very first sketch of your part and press F8

All the icons that show up are constraints. You can right click those constraints to remove them and free the geometry.

Then you can place some new constraints, so the sketch is in the center.

[nima360s]

Im trying to use hori and vert constraint but this is basically what I end up with. I press the middle of one of the 4 sides and then the centerpoint

[SBix26]

Here is what you get with the Centered Rectangle tool (and why I have a hotkey assigned to that tool).  You can easily add a diagonal construction line or two to your existing rectangle, plus a parallel or perpendicular constraint to make it work the same.  Note that I added the perpendicular constraint between the two diagonals to force it to be a square, requiring only one dimension.

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Sam B

Inventor Pro 2025 | Windows 11 Home 23H2

[CCarreiras · Accepted solution]

You have to add Horizontal and vertical constrains between the CENTER LINE POINTS and the ORIGIN POINT:

Its one minute job...

If you place your part, we can check how you are doing it and suggest the proper way to do it.....