At Bray, we use a slotted spoil board with our CNC Router. This enables us to attach clamps to a t-slotted table below:

One of the legs in the foam jig

In the past, we have used the Rockler Hold Down Clamps to secure material. However, this clamp can damage our router bits due to  collisions with the clamps:

We 3D printed clamps to mitigate this issue. The PLA and ABS plastic clamps prevented damage to the bits from collision:

However,the plastic clamps cracked under the clamping forces:


The clamps were then printed with a combination of nylon and carbon fiber on a Markforged Mark Two 3D Printer:

These clamps were much stronger and able to flex without cracking. The clamps were tested on the mill to simulate a bit collision.  The milled carbon fiber broke into fairly large chips.  There was a concern that the carbon fiber and nylon material might melt onto the bit. However, the bit came out clean. Check out the video clip below:

Testing carbon fiber clamp on mill