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Straining

A project log for Interact

Physically interacting with the world can be extremely difficult for some. This project aims to make it a little easier.

Mike TurveyMike Turvey 08/03/2020 at 20:090 Comments

When I started switch adapting toys, I quickly found out that adding a working switch port is only half the battle.  It's got to be robust.  Siblings will take a switch adapted toy and ruthlessly drag it around by the switch cable.  So, I learned the importance of making things strong and "toddler proof."   

Here, you can see a couple of aspects that protect the switch from being tugged all about.  The obvious protection is the curving inside the switch with posts to keep the cable in place.  It dissipates even a strong tug on the cable.  I'm still a little concerned about the long term protection this will provide with repeated tugging.  If that becomes an issue, it may be necessary to place a glob of hot glue around the wire at the base of the switch.  So far, I haven't seen any failures here, so we'll see.

The other protection is more subtle.  Another failure mode is where the wire goes into the switch.  With prolonged use, this point will flex repeatedly and the copper wires can break inside of the sheathing.  That's why you see strain reliefs on so many cables-- basically to spread that bend over a larger area.  But there's no good way that I'm aware of to add a traditional strain relief here using traditional 3d printing without adding undue complexity.  (I'm sure something could be done with TPU, for example, but keeping this easy to manufacture with materials just about anyone would have is a priority of mine).  So, instead, I molded a U channel that the wire sits in.  This resists the bending, and the resistance increases as the wire gets closer to the entrance hole.  The intent is spread the force of a bend over a longer area, as flexing of the wire laterally requires it to be pulled up and out of the U channel.  I'm curious to see how this works long term-- crossing my fingers.

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