## Datum plane tangent to surface

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FredOP
Posts: 51
Joined: Sat Sep 26, 2020 1:25 pm

### Datum plane tangent to surface

How can I make a datum plane that would be tangent to the surface ? Or at the point on the surface closest to fixed point in space.
Attachments
revolution.FCStd
revolution.png (57.6 KiB) Viewed 441 times
chrisb
Posts: 28855
Joined: Tue Mar 17, 2015 9:14 am

### Re: Datum plane tangent to surface

It is not yet possible to place a tangent in Sketcher in the middle of a B-spline, leave alone a to curve controlled by such B-spline. You can compose the B-spline from several tangent segments though and use the endpoints.
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
freedman
Posts: 1680
Joined: Thu Mar 22, 2018 3:02 am
Location: Washington State, USA

### Re: Datum plane tangent to surface

Here is another option. Create a datum plane above the shape and scar the surface with a sketch. This gives you two lines ( in Green) to create an additional datum plane that is tangent, we are splitting hairs here but at least this gives alot of control on all surfaces.
Attachments
slice1.JPG (42 KiB) Viewed 376 times
saso
Posts: 1584
Joined: Fri May 16, 2014 1:14 pm
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### Re: Datum plane tangent to surface

revolution_tangent_plane.FCStd

DatumPlane is using edge of the Revolution as support and is set tangent to the surface by FrenetTB map mode and positioned by the map path parameter.

planebyedge.gif (805.37 KiB) Viewed 350 times

DatumPlane001 is using the DatumPoint and the face of the Revolution as supports and is set tangent to the surface by the TangentPlane map mode. DatumPoint is using the Line and the face of the Revolution as supports, you can double click on the Line and move the outer point around to change the position (activate the DraftWB before). Instead of the Line you can use a sketch or other tools to have a more precise control over the exact position of the DatumPoint.

Note, regardless if you use the Line, the sketch or some other similar tool, you don't have to make the line tangential to the surface, the line is used only to drive the position of the point on the surface, the TangentPlane map mode will make the plane tangential.

planebyline.gif (750.39 KiB) Viewed 352 times
Last edited by saso on Tue Oct 20, 2020 12:22 pm, edited 4 times in total.
freedman
Posts: 1680
Joined: Thu Mar 22, 2018 3:02 am
Location: Washington State, USA

### Re: Datum plane tangent to surface

I can't wait to try this.... Really, I need to load the Draft workbench first, what's that all about? Loading it does what!
Thanks for showing this.
chrisb
Posts: 28855
Joined: Tue Mar 17, 2015 9:14 am

### Re: Datum plane tangent to surface

saso wrote:
Sun Oct 18, 2020 8:30 pm
DatumPlane is using edge of the Sketch as support and is set tangent to the surface by FrenetTB map mode and positioned by the map path parameter.
Is it possible to make it tangent to two points of the solid?
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
saso
Posts: 1584
Joined: Fri May 16, 2014 1:14 pm
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### Re: Datum plane tangent to surface

chrisb wrote:
Mon Oct 19, 2020 3:50 am
Is it possible to make it tangent to two points of the solid?
I am not sure I understand the idea, on a curved surface like this the plane will always be tangent to it just in a single point, if you want to define a plane differently then you normally need three points to define it or a point and a line,... ?
saso
Posts: 1584
Joined: Fri May 16, 2014 1:14 pm
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### Re: Datum plane tangent to surface

freedman wrote:
Mon Oct 19, 2020 1:05 am
You don't have to do it all the time, just the first time when you open FreeCAD. It is because the Line is from the DraftWB and at least on my system it has given me errors that it does not recognize the command when I double clicked on it to edit it after I restarted FreeCAD, so it is just so that the DraftWB tools get loaded. But as I said you can use a sketch or other tools instead.
mario52
Posts: 3215
Joined: Wed May 16, 2012 2:13 pm

### Re: Datum plane tangent to surface

hi

tray Macro_WorkFeatures macro

mario
Maybe you need a special feature, go into Macros_recipes and Code_snippets, Topological_data_scripting, Dialog creation. My macros on Gist.github.
GlouGlou
Posts: 2611
Joined: Sun Apr 05, 2015 9:02 am
Location: La Rochelle, France

### Re: Datum plane tangent to surface

This a way to do that. 2 splines perpendicular to a line.
Then use the Revolve's vertex to hook a datumplane.
Attachments
tangentplane.FCStd