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Comment by kh2engab

9 hours ago

When I read 'Hacking washing machines' the first thing that came to mind was how to open that damn thing once the program had finished.

3 comments

kh2engab

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mikeayles  8 hours ago

Most washing machines use a wax motor to lock the door, it heats up wax to cause it to expand when it melts, which drives a pin. They're fairly failsafe as if you kill power, they will open no matter what.

Latching relays/(technically solenoid) could be driven on/off fast, the downside is in a power cut or an emergency, the relay wouldn't release unless specifically driven so.

So the third option is a momentary solenoid, which would need to be powered the whole time the door is shut, and they require a surprisingly significant amount of power. Typically 10-20w. Negligible when it compares to the KW+ heating elements, but they do add up for the energy ratings..

Fwiw, I currently have a haier, which does have one of the second options, and opens immediately after a wash and it's amazing. Can't go back.

But, wax motors continue to be used because they're just the right tool for the job.

  • bob1029  6 hours ago

    You can still buy machines without the lid lock. They use an alternative design that can stop motion quickly enough to meet safety standards. I can open the lid on my washer in the middle of a heavy spin cycle at max RPM if I want to, but it will brake aggressively and come to a halt within 1-2 seconds. Being able to add laundry mid-cycle without asking permission from the computer is really nice.