The pilot truck axle is a rod about 1/4" in diameter and 2.75" long. Such a high aspect ratio part of relatively small diameter would be a relatively high risk to make. It would need to stand vertically and might distort or topple over during fabrication due to the drag of the hot ABS filament being deposited by the 3D printer head. To help mitigate the risk, a feature was added to the top end that caused the Axon build software to add support material to hold up the overhang of the part. The overhangs faced each other of two identical axles thinking that the Axon software would build a support frame between the two axles. Instead the software built a support frame that essentially surrounded each axle and at the top a bridge was thrown across to support the overhangs. This works as shown above. It took seven hours to print the parts due in large part to the warm up time for the two ABS materials when the heads switched at each of the 200+ layers.
The support materials were easily removed mainly by hand. The two axle rods had very little green ABS support material except at the bottom end where the rods were anchored to the raft. The bridge between the two overhang features at the top took a bit more force, but still came away easily.
The above photo shows the two axles that were built, one with the top end towards the camera and the other bottom first. The top has the overhang feature which will be removed and the bottom has the green strips of ABS raft material that need removing. The top overhang feature snapped off nearly clean.
The Dremel tool sanding wheel was used to remove the residue green ABS and smooth out the region where the overhang feature was snapped off. The axles took very little time to clean up. The above photo shows that the axle and wheel fit as built, neither requiring any adjustments.
The pilot wheels are 1.44" in diameter and 0.26" thick and came out well during fabrication as reported in a previous blog. The above photo shows the arrangement of axle and pilot truck wheels.
The pilot truck as in the main drivers have bearings that surround the axle. An assembly of four was created and printed. Unfortunately, the 3D printer experienced a separation of the green raft and support part way the printing process which resulted in two bearings being destroyed. The other two however came out very well.
The two good bearings are shown above in the orientation used for printing. The axle hole in the middle has some support material in place to hold the top of the part during fabrication.
The two good bearings cleaned up with very little work using a model knife to cut away most the material and the Dremel sanding wheel to remove the green strips at the bottom.
The bearings also came out well on dimensions and slipped on the axle with free rotation as built. The above photo shows the axles in their approximate position on the axle. The pilot truck frame will slide on the slots of the bearings after assembly.
The above photo shows the approximate position of the pilot truck wheels under the front frame. The open section of frame to the left of the pilot wheels will mount the cylinder assembly.
Above photo shows a bit more of the front frame section from drivers to pilot wheels.
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