Part Design – Shape binder

How to link Sketches, Edges and Faces to Another Sketch ( without formulas. )

For a careful fully detailed explanation of the Shape Binder head over to: https://wiki.freecadweb.org/PartDesign_ShapeBinder. The article there provides more use cases, more details and the limitations.

When designing a multi-body part or multiple parts, the designer is often in need of a simple way to cross reference between Bodies. A common example being matching up holes between bodies. We can use the Shape Binder tool to accomplish this task, in a robust way.

You can watch a video tutorial here:

And here is the model that the video tutorial produces :

https://mathcodeprint.com/freecad-primitives-based-case/

The Shape Binder tools is very simple to utilize,. With the Active Body where which you wish to utilize features of the source bodies you add a Shape Binder.

One of the cited examples for the Shape Binder is aligning case holes. It is a nice straightforward example, so lets try it out.

First let’s build the base of our case. We can use the additive box, thickness and additive cylinder to get there more quickly.

The Case

Add a Box

Set Length to 80, Width to 120 and Height to 10 ( Phone Sized )

Add a Fillet to the Four corners.

Add a thickness using the top face as the selection, leave the defaults and click ok.

Add a Cylinder with radius of 5 and height of 10,

Select the radius of your fillet, inside the case, and the attachment and reverse the cylinder ( flip sides ). I used this as the attachment so we can change the height of the box without affecting the cylinders.

Make sure the attachment mode is Concentric and use Flip Sides if the cylinder is facing the wrong way.

Repeat this four times.

Subtract a cylinder with a radius of 2.5 and height of 8

Attach the subtractive cylinder the same way the additive cylinder was attached.

If the the red prototype cylinder is not within the post, click the “Flip Sides”

Repeat for all four corners

The Lid

Add a Second Box, usr the same dimensions as the first box.

With the Body of the second box active select the Shape Binder.

In the Shape Binder dialog, toggle the Add Geometry. The button will remain greyed out until you select a Geometry.

Select the face of one of the Posts inside the first box

Repeat this with all four post-faces

If you have done everything correctly you model should look like this:

Finalize the “Datum shape parameters” with the OK button.

To make holes, select Subtractive Cylinder and click one of the Yellow circles.

Set the Cylinder radius to 2.5 ( You can use the scroll wheel )

Repeat for all four posts.

The Shape Binder relies on Internal naming so it can still be easily broken, but there certainly ways to mitigate. For instance, attaching the Cylinders that make up the posts to a feature that is less likely to change.


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