Datum plane tangent to surface

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FredOP
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Datum plane tangent to surface

Post by FredOP » Sun Oct 18, 2020 1:31 pm

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.
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chrisb
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Re: Datum plane tangent to surface

Post by chrisb » Sun Oct 18, 2020 3:21 pm

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.
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freedman
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Re: Datum plane tangent to surface

Post by freedman » Sun Oct 18, 2020 7:54 pm

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.
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saso
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Re: Datum plane tangent to surface

Post by saso » Sun Oct 18, 2020 8:30 pm

revolution_tangent_plane.FCStd
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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
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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
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Last edited by saso on Tue Oct 20, 2020 12:22 pm, edited 4 times in total.
freedman
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Re: Datum plane tangent to surface

Post by freedman » Mon Oct 19, 2020 1:05 am

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
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Re: Datum plane tangent to surface

Post by chrisb » Mon Oct 19, 2020 3:50 am

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?
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saso
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Re: Datum plane tangent to surface

Post by saso » Mon Oct 19, 2020 7:07 am

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,... ?
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saso
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Re: Datum plane tangent to surface

Post by saso » Mon Oct 19, 2020 7:12 am

freedman wrote:
Mon Oct 19, 2020 1:05 am
Really, I need to load the Draft workbench first, what's that all about? Loading it does what!
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
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Re: Datum plane tangent to surface

Post by mario52 » Mon Oct 19, 2020 12:09 pm

hi

tray Macro_WorkFeatures macro Image

Image

mario
Maybe you need a special feature, go into Macros_recipes and Code_snippets, Topological_data_scripting, Dialog creation. My macros on Gist.github.
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GlouGlou
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Re: Datum plane tangent to surface

Post by GlouGlou » Mon Oct 19, 2020 6:42 pm

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