Quote:
Originally Posted by KrazyCarl92
It seems like you're misinterpreting the suggestion of reaming. The suggestion was to use a reamer on the plastic molded part after it ejects from the mold, not on the injection mold itself. This would allow the manufacturer to hit tighter tolerances on the hole diameter than can be achieved through molding alone, and without any risk to the mold. This is called "rework" and is often avoided in the real world because it is time-consuming and potentially labor intensive at high volumes (higher cost). It's not desirable, but if a manufacturer is in a position where it is the only way good parts can be sent out the door it is sometimes a reasonable course of action. However, Andy stated it is not clear whether this tighter tolerance would even make much of a difference.
I would say "a reamer? oh that's easy enough to test on a few parts", but it sounds like AndyMark is unable to reproduce the problem on more recently molded parts (actually a good thing, but frustrating if you're troubleshooting the issue...). So it would be difficult to evaluate the effect of reaming without a failing baseline for comparison.
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I know you meant on the Part itself, not the mold, but I'm concerned about shattering since although reaming is a light process, the injected plastic is very brittle and could snap or fracture under very light stress. Again, my team is modifying the 3D part to increase structural integrity before printing. If someone could try reaming and see how goes that would be great.
However, I do not think the problem lies in the tightness of the bearing recess, but in the thickness of it's walls. The recess has very little support along the edge of the bearing, and when it is under a shock load such as after crossing the rock wall, it shatters. This is what our 3D model adresses, by filling in the large gaps around the recess, we add extra, and constant support throughout the arc of the pulley's rotation. If anyone has thoughts on this I'd love to hear.
-Jacob