How to rotate a sketch, using its side as axis?

[ifohancroft]

Hi,

I have a FreeCAD document, that has two sketches, each of them looking like this:

one.png (9 KiB) Viewed 861 times

Together, from the top, they look like this:

two.png (9.08 KiB) Viewed 861 times

From the right side, they look like this:

three.png (8.2 KiB) Viewed 861 times

I want to rotate the second sketch so from the side, they will look like this:

four.png (8.63 KiB) Viewed 861 times

However, instead, when I rotate the second sketch on the X axis by 5 degrees, I get this:

five.png (8.85 KiB) Viewed 861 times

I presume this happens because the second sketch gets rotated around the middle as opposed to by the side.

How do I rotate it to achieve the result I want?

I will upload the FreeCAD file as an attachment in the next comment.

[ifohancroft]

Here is the FreeCAD file:

Curve-Test.FCStd

(15.08 KiB) Downloaded 27 times

[bejant]

In the Placement widget (not the Placement Properties in the Data tab) first tick "Apply Incremental Changes" to True, then change the Center, and finally do the Rotation.




https://www.freecadweb.org/wiki/Tasks_Placement

[papyblaise]

hi it's that you went : you have to type the position of the hinge

[ifohancroft]

@papyblaise Thank you! That worked. Not sure why I couldn't get it to work earlier. Btw the right position is 9.525, not 9.75.

@bejant Thank you! Maybe I'm an idiot but I cannot get your method to do anything. I may have a problem understanding how the placement dialog works or something:

1. After I check Apply Incremental Changes, do I hit Apply or Ok?
2. After I have enabled Apply Incremental Changes (without hitting Apply or OK) I change the Y of the center to -9.525.
3. Then I change the rotation angle but nothing seems to move?! I thought maybe there is no live preview and I need to hit OK, however even after I do, there is still nothing changed?! I thought maybe I then need to rotate via the Attachment Angle in the Data Tab but it rotates as if I haven't do anything in the Placement Widget.

What am I failing to understand or do?

[Vincent B]

A easy way is to use a datumplane.
choose an edge and make a datumline, make a datumplane with it.
rotate it on the right axle as needed.
Then map a sketch on the datumplane and draw the next sketch.

[papyblaise]

A easy way is to use a datumplane.

yes but the question is not to draw a sketch as an angle , but I have two sketch on the same plan : how to rotate one around a line of the second

[Vincent B]

La fin justifie les moyens.

[ifohancroft]

@GlouGlou Thank you! That's a good idea too. I keep forgetting about datum planes.

@papyblaise What GlouGlou said also works for me. I should have probably posted what I want to do that I need this step for.

I have found an easier way that works for me. Sketching the side profile, then padding towards the back and then creating the holes.

Now I need to figure out an easy way to also create such "strips" to the sides, with also 5 degree angle between the "strips". I have figured out how to do it but after I finish it, I need to check if there is a better way.

[bejant]

1. After I check Apply Incremental Changes, do I hit Apply or Ok?

No, just tick the Apply Incremental Changes..." tick box to True (do this first).

2. After I have enabled Apply Incremental Changes (without hitting Apply or OK) I change the Y of the center to -9.525.

I think you want to make Y = 9.525 (no negative sign).

3. Then I change the rotation angle but nothing seems to move?! I thought maybe there is no live preview and I need to hit OK,

You should be changing the Attachment Offset using the Placement widget, don;t think I was clear before. In the Placement widget, above the "Apply Incremental Changes..." tickbox, change the Axis to Y and then change the Angle field to whatever angle you need. There is a live preview so you should see the Sketch rotate as you change the Y angle value.

I trued to use your file but got a message: "Cannot compute Inventor representation for the shape of ((the file name)" so I just tried using my own new file.

OS: Ubuntu 18.04.3 LTS (ubuntu:GNOME/ubuntu)
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.19. (dated 2020-01-05)
Build type: Release
Python version: 3.6.9
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)