Parametric Clip-On Hook

I made this as a cad excercise for myself and to have a model that can handle almost all pipes and beams i would want to add a hook to. The first use case was to add a clable holder to a square beam under the table.

How to set the Parameters?

To set the parameters yourself you need to download and install FreeCad: https://www.freecad.org/downloads.php?lang=en

Following that download the parametric_clip_hook.fcstd file from here and open it with free cad. If you are familiar with FreeCad jump to the explanation of the parameters. Following that download the parametric_clip_hook.fcstd file from here and open it with free cad. If you are familiar with FreeCad jump to the explanation of the parameters. 

When you open the file you should see a tree view on the top left with an element called parameters. When you open the file you should see a tree view on the left with an element called parameters. Click on the element labled parameters and a table view will appear on the bottom left below the tree view. If you want to set a parameter click a value on the right next to the name of the parameters and enter a numeric value.When you open the file you should see a tree view on the top left with an element called parameters. When you open the file you should see a tree view on the left with an element called parameters. Click on the element labled parameters and a table view will appear on the bottom left below the tree view. If you want to set a parameter click a value on the right next to the name of the parameters and enter the desired numeric value.

What do the Parameters mean?

Width and Length

Width and length determine the main dimensions of the clip in the x and y directions from the hook. The values describe the inner diameter, so enter your measurements from your bar or pipe. On the left you see a hook with a width setting of 60mm and a length setting of 30mm on the right the values are swapped.

Roundness

The roundness value is a percentage and goes from 0 to 100 and decribes the rounding of the corners. If width and length are equal and roundness is set to 100 the resulting clip is a circle. In case the clip is not square a roundness of 100 will result in semicircles at the shorter edge (pill shape). The image on the left is the result of setting a width of  60mm and a length of 30mm with a roundness set to 100.

Thickness and Height

The height value determines the z dimension of the hook whereas the thickness describes the wall strength. For a stronger hook increase thickness. On the left you see a hook with a height of 10 mm and a thickness of 5.8 mm on the right you see a hook with a height of 20 mm and a thickness of 2.8 mm

Opening Angle and Opening Direction Angle

The opening angle determines the width of the slot cut out of the hook. The effect is illustrated in the following figure. The origin of the cutout will always be in the center of the clip part of the hook. The opening direction angle is the angle of the bisector of the opening angle relative to the x axis. So an opening direction angle of 90° would show straight up the y axis. The example on the left shows an opening direction angle of 99°. If the hook is intended to be slotted onto a plate, like for example to hold headphones on a table the opening angle can be set to 180° and above.

Hook Lenght and Hook Neck Length

The hook neck length describes the distance of the hook from the clip and can be used to adjust opening width. The hook length is the distance of the point of the hook from the inside of the neck. On the left you can see a hook with a hook length of 45 mm and a hook neck length of 16 mm whereas on the right the hook length is 18 mm and the neck length 32mm. The hook curvature in both cases is set to 45 and will be explained in the next section.

Hook Curvature

The hook curvature works in a similar fashion to the roundness of the clip and is a percentage that describes how much of the neck should be circular. If you set the last example with a hook length of 18 mm and a neck length of 32mm to 0, the hook will look like the depiction on the left.

Setting a hook curvature of 0 makes the following parameter almost unneccessary, which will be addressed in a coming revision.

Hook Upper Angle

The last parameter determines how far around the corner the end of the hook bends. The size of the bend is dependend on how rounded the hook is. For small curvatures the bend almost disappears. All displayed examples use a hook upper angle of 96°.

Limitations

This far the parameters for the clip can only describe rounded rectangles. Parallelograms like diamond shapes or trapezoids and triangles are currently not possible.