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Mechanism Prototypes #2

A project log for Functional Pip-Boy 3000 Mk4

Bringing a virtual device into the real world.

zapwizardzapwizard 06/06/2016 at 03:580 Comments



Hey Folks, it has been a month since I posted an update. Real-life is getting busy again. But I did find time to go in an fix issues with my first round of prototypes.



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The radio knob assembly was re-designed such that the needle and the electronically read potentiometer were directly connected. In the first build they were separated by a secondary gear, and so if a gear tooth ever slipped the readout would be inaccurate. The new design works very well and is more robust. I also managed to print up some temporary gauge faces. Everything with this prototype works well, so I don't expect any more changes to this part of the design.



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The Holotape cassette mechanism was next. I managed to fix the closing mechanism, and all the springs. But when there is too much friction in the system the eject mechanism can get caught up during opening. I may make a few more tweaks to ensure the mechanism is robust and can't get caught up. Otherwise the design is close to finished.




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The cable retraction mechanism unfortunately is a different story. I did make some improvements, such as adding a guide for the cable to reel into.
I also removed a spring from a 3ft tape measure, it was the perfect size, however the spring simply isn't strong enough to overcome all the fiction in the system. The reel will feed out and retract if the catch isn't installed, or the slip-ring PCB, but just barely. If the spring were about 3x stronger than the mechanism would work great. However, I can't find any small (20mm Dia x 6mm Thick) springs which are stronger than I have now.



The 3mm thick cable also plays a part in the friction. I have taken apart a retractable USB car-charger which works very much the same as my mechanism and using a smaller spring, but it also uses a much thinner cable. That thinner cable doesn't look game accurate to my eyes, and it only has two wires so would only support charging, and no actual data. Still reverse engineering the car charger has gave me a few ideas, so I will take one more crack at this mechanism to see if I can get it all working.

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