YouTuber demonstrates technique for stable FDM 3D printing

YouTuber James Clough (Clough42) is working on converting his PM-728 milling machine to CNC and needs a suitable holder for his toolpost grinder. For a one-time use, the holder should above all be functional, quickly available, and sufficiently stable. Instead of opting for a complex metal solution, he decides on a 3D-printed Multifix holder made of PLA as a practical interim solution.

The component combines the complex toothing of the Multifix tool holder with a precise bore for the grinding spindle. Clough designs the part in Fusion 360, but discovers that a freely available GrabCAD model of the Multifix geometry is inaccurate. He adjusts the contour step by step until the holder locks cleanly onto the existing tool carrier.

The biggest challenge lies in the FDM printing itself. Depending on the orientation, the layer lines run either through the clamping hole or through the anchor holes, weakening the structure there. At the same time, round surfaces create strong overhangs, which would lead to rough surfaces in classic printing with many support structures.

Clough therefore orients the model on a beveled edge and prints it at an angle. This way, the layers run diagonally through the hole and clamping zone and distribute the forces better. To prevent the part from tipping off the print bed on the narrow bevel, he designs a separate rib and connects it to the component via many small bridges.

The rib supports the part during printing, but can be broken off afterwards with little force. In addition, Clough only places tree supports in Bambu Studio where overhangs of more than 30 degrees occur. He chooses standard PLA as the material to avoid warping and ensure a good fit for the Multifix gearing.

In testing, the finished holder sits securely on the Multifix post and holds the toolpost grinder safely in position for light threading work. For continuous operation or high grinding forces, however, Clough recommends a metal part.