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StrongArm

Prototype 1

Here is the first physical iteration of my generatively designed filament spool holder. The aim was to test the fit of the assembly and the way that the arm branches would print, aswell as give an initial idea of scale and strength.

Firstly, the bearing fits well in the conical shaped part at the top end of the arm. However, the tolerance was set slightly too low, allowing the bearing to wobble a little. Since this is a key part that locks the rotating cylinder (featuring in later images) to a fixed axis, the wobble also affects the alignment of the cylinder to the conical shape, despite the fact that they do technically fit together alright, allowing the cylinder free rotation.

The rails of the block part at the bottom end of the arm slot nicely into the body of the Ender 3 Pro, but also with slightly too much wobble, preventing it from sitting flush with the profile of the beam shown below.

The spool holder does technically function (as shown below), but with a large amount of flex towards the front of the printer (pointed away from the camera in this shot). This may be mitigated by the greater rigidity of steel in the final part, but is still worth noting.

Another notable, but easily fixed design issue, is the length of the cylinder which is slightly too short, being only just long enough to reach across the total width of the spool.

Due to the arm being 3D printed laterally along the print bed, the layers within the branches of the arm stack with a small amount of surface contact (as shown below), due to the angle of the branches from the print bed.

I initially considered this to be an issue, but testing the holder seems to have proved the the adhesion is strong enough to support the load of the spool without shearing or buckling past the point of breakage.

Despite this, I would still like to see how this (or something with a similar shape) prints when the branches are aligned closer to parallel to the print bed. This would enable the structural integrity of the arm to rely more on the tensile strength of individual layers, rather than the collective strength of the adhesion between multiple layers (although adhesion between layers would also increase due to larger contact area).

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