# Blender > Parametric Press Fit Kit¶

Tutorial by Rico Kanthatham, Skylabworkshop, 2024

The model originally created by **Fab Guru Santi** (Barcelona), this amazing Blender File utilizes **Geometric Nodes** to create **2D shapes for Week 2 Press-Fit Kits with adjustable parameters**. Parameters allows the adjustments of key dimensions such as slot width and depth…and also allows the specification of the number of sides for the geometry and the number of attachment slots per side. It is an elegant demonstration of Blender as a Parametric modeling tool for Fab Academy.

## Building Santi’s Geometric Nodes¶

### Getting Started with Blender Geometry Node¶

- Change a window to become a Geometry Node editor window…by clicking the icon on the upper left corner of a window…

…then choosing **Geometry Node Editor**

**Select the default cube**(yellow outline) in the 3D Viewport window…click**”+ New”**in the Geometry Node Editor window

OK! Now we are ready to build a new **Geometry Node Tree!!**

### Step 1 > Adding a Curve Circle¶

- In the Geometry Node window…
- Disconnect the
**Group Input**node from the**Group Output**node (left click on one of the connection socket and disconnect the green line).

**SHIFT + A**…to add nodes- …add a
**Curve Circle**node

This will be our

Base Geometryto be modified by parameters and slot cuts

#### Creating Parameters¶

- …connect the Curve Circle’s
**Resolution**and**Radius**input nodes to empty connection sockets (below the “Geometry” socket) in the**Group Input**node. - …
**rename the connection sockets**in the Group Input node from “Resolution” to “No_Sides” by typing**N**in the Geometry Node window to**open the pop-up menu**on the right side. Click the**Group**tab and type**“No_sides”**in the ” ” input window.

### Step 2 > Creating the Press-Fit Slot Geometry¶

We will add a **Quadrilateral** (basically a rectangle) which will be used to cut **Press-Fit Slots** into the Base Geometry.

- Add a
**Quadrilateral**node and a**Math**node. - Select
**Subtract**as the math operation from the drop-down menu in the Math node. - Connect the
**Value**output socket of the**Subtract/Math**node to the**Width**input socket of the**Quadrilateral**node. - Connect the
**Height**input socket of the**Quadrilateral**node to an empty socket of the**Group Input**node…rename it**Slot_Depth**. - Connect the topmost input
**value**socket of the**Subtract/Math**node to an empty socket of the**Group Input**node to make it a parameter…rename it**Material_Thickness** - Connect the bottommost input
**value**of the**Subtract/Math**node to an empty socket of the**Group Input**node…rename it**Kerf**. - Add a
**Subdivide Curve**node and attach its**curve**input socket to the**curve**output socket of the**Curve Circle**node. - Connect the input
**Cuts**socket of the**Subdivide Curve**node to an empty socket of the**Group Input**node…rename it**side Subdivisions**.

The subdivision location of the Base Geometerywill become the locations of thePress-fit Slots.

### Set the Primary Parameters¶

By connecting node sockets to the **Group Input** nodes, we create adjustable parameters in the **Geometry Node Modifier** properties (lower right side of the screen…the blue wrench icon).

Parameters that can be adjusted include…

**Number of Sides**for the Base Geometry- The
**Radius**width of the Base Geometry - The
**Material Thickness**dimension that will define the slot width - The
**Slot Depth** - The lasercutter’s
**Kerf** - The
**Side Subdivisions**

Set these parameters to your liking.

### Instancing the Slot Geometry to the Base Geometry¶

Now that we have the **Base Geometry** with subdivided sides, it is time to instance (duplicate and place) the **Slot Geometry** onto the sides of the Base Geometry at the subdivision locations.

- Add an
**Instance on Points**node - Connect the
**Curve**output socket of the**Subdivide Curve**node to the**Points**input node of**Instance on Points**node - Connect the
**Curve**output socket of the**Quadrilateral**node to the**Instance**input node of**Instance on Points**node

- Add an
**Align Euler to Vector**node and a**Curve Tangent**node. These nodes will allow us to rotate the**Slot Geometry**to its correct perpendicular position on the sides of the**Base Geometry** - Connect the
**Rotation**output socket to the**Rotation**input socket of the**Instance on Points**node

To see what we have made so far, we will temporary…

- Add a
**Join Geometry**node…place it after the**Instance on Points**node - Connect the
**Instances**output socket of the**Instance on Points**node to the**Geometry**input socket of the**Join Geometry**node - Connect the
**Curve**output socket of the**Curve Circle**node to the**Geometry**input socket of the**Join Geometry**node

…and you should see a **skeletal preview** of what we have made so far. **Play with parameters and see how things change.** Don’t mind that it looks a little weird at this point…we skill have more nodes to add!

Tip:If you want to see what a node does…select it and pressMto mute and unmute its effect!

### Refining the Press-Fit Part Base Geometry¶

Now that we had a preview of the geometry, let’s…

- Delete the
**Join Geometry**node (select it and click**X**). - Add the
**Fillet Curve**,**Fill Curve**and**Mesh Boolean**nodes - Connect the
**Curve**output socket of the**Curve Circle**node to the**Curve**input socket of the**Fillet Curve**node - Toggle the
**Poly**option for the**Fillet Curve**node…and set the**Count**to about**5** - Connect the
**Radius**input socket of the**Fillet Curve**node to an empty socket of the**Group Input**node to make it a parameter…rename it**Corner Radius**. Set the Corner Radius to something you like. - Connect the
**Curve**output socket of the**Fillet Curve**node and connect it to the**Curve**input socket of the**Fill Curve**node - Toggle the
**N-gon**option of the**Fill Curve**node - Connect the
**Curve**output socket of the**Fill Curve**node and connect it to the**Mesh 1**input socket of the**Mesh Boolean**node - Set the
**Mesh Boolean**operation to**Difference**(since we want to cut holes in the**Base Geometry**with our**Slot Geometry**)

Our **Base Geometry** now has a nice shape with round corners!

### Organizing the Node Tree with Frames¶

The node tree can get a bit confusing after many nodes have been added. It is helpful when related nodes are grouped together to make later modifications a bit easier.

- Add
**Frames**and you will see a small black rectangle - By selecting a number of related nodes (hold down the SHIFT key as you select them) and then dragging them into the empty black
**Frame**rectangle…you will create a moveable group of nodes within the node tree - The
**Frames**can be given labels by typing**N**in the Geometry Node Editor window to toggle open the side menu…then in the**Node**tab you can enter a name in the**Label**text input cell

Here are my framed groupings…

### Adjusting the Instanced Slot Geometry¶

The next few nodes added will adjust the appearance of the **Slot Geometry** which will then be added into the **Mesh Boolean** node as the cutting or **Difference** geometry at the **Mesh 2** input socket

- Add the
**Separate Geometry**,**Fill Curve**,**Extrude Mesh**nodes - Set the type option of the
**Separate Geometry**to**Instance** - Connect the
**Geometry**input socket of the**Separate Geometry**node to the**Instances**output socket of the**Instance on Points**node - Connect the
**Selection**output socket of the**Separate Geometry**node to the**Curve**input socket of the**Fill Curve**node - Toggle the
**N-gons**node of the**Fill Curve**node - Connect the
**Mesh**output socket of the**Fill Curve**node to the**Mesh**input socket of the**Extrude Mesh**node - Set the mesh selection type to
**Faces** - Connect the
**Mesh**output socket of the**Extrude Mesh**node to the**Mesh 2**input socket of the**Mesh Boolean**node

Not done yet! A couple more nodes to add…

- Add 2
**Math**and an**Index**node - Set the operation for one
**Math**node to**Add** - Set the operation for the other
**Math**node to**Floored Modulo**(Returns the positive remainder of a division operation) - Connect the
**Index**output socket of the**Index**node to the top**Value**input socket of the**Floored Modulo**node

The

Indexnode provides the sequential number associated with each of theSlot Geometryinstance

- Connect the bottom
**Value**input socket node of the**Floored Modulo**node to the**Value**output socket of the**Add**node - Connect the
**Value**output socket of the**Floored Modulo**node to the**Selection**input socket of the**Separate Geometry**node - Connect the top
**Value**input socket node of the**Add**node to the**Side Subdivisions**socket of the**Group Input**node - Input the number
**1**into the bottom**Value**cell of the**Add**node

I will drop a frame to group all these new nodes…

### Oops!! I made a mistake!!¶

Early on, from the **Quadrilateral** node I connected the **Width** input socket to the **Material Thickness** socket…and the **Height** input socket to the **Slot Depth** socket…of the **Group Input** node. It should be the opposite.

**Width** is the **Slot Depth** of the **Slot Geometry** while **Height** is the Material Thickness (I renamed the parameter to “Slot Wide”).

Here is an image of the corrected connections…

After making this correction, we can see a great preview of our **Press-Fit Part** with the **Slot Geometry** carving slots out of it at the subdivision points specified at the beginning. Hooray!!

### The Final Touches > Add Fillets¶

Now we will add a few final nodes into the **Output** group of nodes…in between the **Mesh Boolean** node and the **Group Output** node. These last nodes will add **fillets** to our geometry.

- Add the
**Mesh to Curve**,**Fillet Curve**and**Fill Curve**nodes

I won’t even bother to describe the process this time…the connections are so easy. Here is an image to refer to…

**That’s it!!! All done**

### The Parametric Press-Fit Part in Blender¶

Here are some sample images of parts created with the model…

**3-Sided with 2 Slots per side**

**4-Sided with 2 Slots per side**

**5-Sided with 1 Slots per side**

And here is the Blender File for you to play with!

And here is a link to **Luis Pancheco** page where he shows how to use a script to generate gcode from the Geometry Node shapes