Detect that dishwasher arm is not spinning

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Starina

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#280345 10-Dec-2020 00:06

Looking for a solution how to detect that dishwasher arm is not spinning because it's blocked by dishes.

We've got a new dishwasher from F&P: double dishdrawer. Works fine, but it's much easier to make a mistake while loading the dishes. Especially with lots of people and kids having access to it.
Any ideas what sensor I can use to detect that the arm is spinning?
I know about hall sensor, but the distance should be really small for it to work. Not sure where I can install it. Infrared and ultrasound probably won't work in the water.
It'll be connected to ESP8266 and eventually will send me a notification that something is wrong.

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Smpl Mnmlst
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#2619041 10-Dec-2020 03:28

Not sure about dish drawer but with our conventional washer, I just give the arm a spin by hand before closing the door - to make sure it’s unimpeded and spinning freely. Low-tech approach.

Sometimes I just sit and think. Other times I just sit.

SirHumphreyAppleby

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#2619049 10-Dec-2020 06:52

eracode:

Not sure about dish drawer but with our conventional washer, I just give the arm a spin by hand before closing the door - to make sure it’s unimpeded and spinning freely. Low-tech approach.

It's quite difficult to do that with these models. If you lift out the basket and lift the door underneath it which gives access to the filter, you can often reach the arm and spin it.The filter will also loosen over time as the rubber degrades. When this happens, it will knock the arm off during loads, so checking down there before starting a load is probably a good routine to get into.

Sorry, I have no recommendations for sensors other than the human ear. You can often hear when things aren't working as they should.

k1w1k1d

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#2619054 10-Dec-2020 07:29

I usually do the same as eracode.

Inside the dishwasher is a rather nasty place to mount a sensor: hot, wet, with a strong chemical cleaner.

timmmay

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#2619055 10-Dec-2020 07:29

Probably easier to use a low tech method like spinning it as above, or listening once you start it. You'll get used to it fairly quickly and won't need anything to check it for you.

nickb800

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#2619061 10-Dec-2020 07:50

I'd imagine something inside the dishwasher 'washing area' is pretty much impossible.

Given you seem keen for a tech solution - I wonder if you can put some sensor in the 'engine bay' underneath that detects the arm spinning e.g. current transformer on the power feed to the arm spinning motor. I'm not sure if there's some sort of slip coupling between the motor and arm, but regardless there may be a subtle difference in current draw between when it's operating correctly and when it's not.

Bung

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#2619082 10-Dec-2020 08:35

I don't know if a Dishdraw is the same as more conventional washers but usually the spin is imparted by the water squirting out of some nozzles on the arm. Stop the arm and the pump continues to squirt the same amount of water, it just isn't being directed into all the dishes.

You can anticipate some problems. We had some spatulas that were long enough to stop the arm if they were stood up in the basket - fixed by chopping a couple of cm off length of handle. Plastic that retained water in concave areas facing up - if it didn't affect normal use add a small drain hole.

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nickb800

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#2619090 10-Dec-2020 08:42

Ah bummer, that rules out that idea. Only thing left to do externally could be some sort of vibration sensor, calibrated to know what is normal and what is not. Bit of a moonshot really

Eva888

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#2619115 10-Dec-2020 08:59

I always lay all long handled utensils flat across the cups or nestled down the sides. Boards stacked at the edges where arm doesn’t reach.

trig42

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#2619126 10-Dec-2020 09:07

This is why I load the dishwasher.

We have dishdrawers, and the most frustrating thing is halfway through unloading realising that half the dishes are not clean, and discovering that someone has chucked something in there which has gone down though the racks and impeded the arm.

Agree with above, a quick spin of the arm after loading (can usually get a finger through somewhere).

Paul1977

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#2619127 10-Dec-2020 09:07

eracode:

Not sure about dish drawer but with our conventional washer, I just give the arm a spin by hand before closing the door - to make sure it’s unimpeded and spinning freely. Low-tech approach.

This is what I do with our standard dishwasher - the missus never does though :(

Looks like it would be a lot more fiddly with a dishdrawer, but if you removed one or two plates you might be able too do the same thing (just going by pictures on F&P website)?

It would actually be a really good feature for dishwashers to stop and beep with an "arm obstruction" light/message. I wonder why they've never implemented something like this on dishwashers.

linw

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#2619162 10-Dec-2020 09:21

We inherited a F&P dish drawer in our place and immediately had that problem. Took a while to find some broken mesh in the base of the cutlery basket. So, guess what the knives did? Wired the gap up and OK now.

But, yes, it can be fiddly doing a test spin but better than having to rewash and dry the load! And, also, it took me a while to realise the blade was spun by water pressure!!

Can't imagine how a sensor could survive in the horrendous environment. Especialy a home grown one.

Sorry, no help to you.

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Bung

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#2619186 10-Dec-2020 09:33

Early NZ level crossing alarms were like a propeller with a loose attached ring at the tip of each blade. As it rotated the rings struck a bell. We get a muted variation depending on where the large plates are stacked. Some slots result in the plastic jets on the arm just clipping the plate so you get a rhythmic clonk clonk.

nickb800

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#2619195 10-Dec-2020 09:39

Could you epoxy a magnet on the arm and have a reed switch outside the dishwasher body to detect it? Would need to consider sensing distance

Dairyxox

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#2619198 10-Dec-2020 09:45

Just train an AI agent to listen to the washing machine using a mic. It will learn the difference in noise of a non-spinning arm. No internal sensor needed.

eracode

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#2619289 10-Dec-2020 11:29

Is this problem a result of bad design by F&P? Surely it shouldn’t happen so easily.

Sometimes I just sit and think. Other times I just sit.

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