airfry
Posts: 5
Joined: Sat Aug 10, 2019 4:32 pm

Homemade airfryer

Sat Aug 10, 2019 7:01 pm

Edit: Decided to go the homemade route a few posts down. Updated the original title to reflect that.




Original post as follows:

I've been considering building a custom "airfryer" to be controlled by a Raspi, as it seems pretty straightforward - not much more than a heating element plus a fan in an air-circulating enclosure. But after reading some other threads regarding similar functionality, it looks like it could actually be easier and safer to use an existing, pre-made airfryer or similar mini-oven.

If you're unfamiliar with airfryers, they're pretty compact and make delicious, relatively healthy food: https://youtu.be/9pbJUn2y6Aw?t=160

I was wondering if anyone has any experience with or might be able to point me in the right direction for controlling pre-made appliances like this with a Raspberry Pi.

I'm still open (and would prefer) to build something of my own so that it can be more easily customized (plus it'd probably be cheaper right?), but using an existing appliance seems more realistic right now.

This is what I'm currently using at home: https://www.usa.philips.com/c-p/HD9641_ ... n-airfryer

There isn't much to it other than setting the temperature and time to cook. It seems like there should be some way to "hook" into the appliance's circuit board and send whatever signals are necessary to 1) set the temperature 2) set the time to cook and 3) turn it on.

Does this sound feasible? Or should I just make my own?

Also, FWIW, I have a bachelor's degree in computer hardware engineering but I'm really rusty in that regard as I've spent the last decade working on software.
Last edited by airfry on Sun Aug 11, 2019 5:42 pm, edited 1 time in total.

blimpyway
Posts: 184
Joined: Mon Mar 19, 2018 1:18 pm

Re: Controlling a premade appliance?

Sun Aug 11, 2019 1:24 am

Yes you can but since you will likely have to deal with mains AC switching, you shouldn't.

And the obvious question is why? How would it improve the interface & taste the built-in buttons/dials/whatever the fryer already provides?

PhatFil
Posts: 1411
Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: Controlling a premade appliance?

Sun Aug 11, 2019 3:42 am

Well Interfacing with the existing control system may not be possible but could be worth investigating.

If not possible you could control each aspect of the system Fans heaters motors solenoids etc vi your pi either directly or via a wifi or bluetooth enabled slave dev board But would also need to replicate the various programs too.

Neither will be easy.. But could be educationally fun..

An alternative approach might be to find a device you can program in advance like a washing machine, and simply use a smart switch to power on the device on demand. tasmota is a firmware replacement for many smart devices that removes reliance from remote comercial servers and gives you local control, imho a number of tasmota compatible devices would make ideal replacement controllers too..
https://github.com/arendst/Sonoff-Tasmota/wiki

drgeoff
Posts: 9886
Joined: Wed Jan 25, 2012 6:39 pm

Re: Controlling a premade appliance?

Sun Aug 11, 2019 10:42 am

Any decent air-fryer should have safety mechanisms eg to prevent dangerous overheating if fan or thermostat fails. Be sure that your homebrew version has similar or your mods to a premade one do not compromise them.

And sorry to be blunt but "a bachelor's degree in computer hardware engineering", even without 10 years of rust, would be no evidence whatsoever of your competence to be attempting either approach.

airfry
Posts: 5
Joined: Sat Aug 10, 2019 4:32 pm

Re: Controlling a premade appliance?

Sun Aug 11, 2019 4:14 pm

Thanks for the quick replies! :D
blimpyway wrote:
Sun Aug 11, 2019 1:24 am
And the obvious question is why? How would it improve the interface & taste the built-in buttons/dials/whatever the fryer already provides?
Idea is to have many of them working alongside each other to cook many different things at once. Some things also taste better if you cook them on lowish heat for a while, and then crank it up for a few minutes at the end, which currently has to be done manually with every device I've seen thus far.
PhatFil wrote: An alternative approach might be to find a device you can program in advance like a washing machine, and simply use a smart switch to power on the device on demand.
I had looked into existing WiFi powered airfryers. Only one I found was by some company called "Gourmia" but the Philips is overall better for my use case.
PhatFil wrote: tasmota is a firmware replacement for many smart devices that removes reliance from remote comercial servers and gives you local control, imho a number of tasmota compatible devices would make ideal replacement controllers too..
https://github.com/arendst/Sonoff-Tasmota/wiki
This is really interesting. Thank you for this.
drgeoff wrote: Any decent air-fryer should have safety mechanisms eg to prevent dangerous overheating if fan or thermostat fails. Be sure that your homebrew version has similar or your mods to a premade one do not compromise them.
Yup. Most of the safety has already been handled with the premade devices, and is exactly the reason I want to try to reuse them. I'm sure there are more than a handful of potential safety hazards someone like myself would overlook.
drgeoff wrote: And sorry to be blunt but "a bachelor's degree in computer hardware engineering", even without 10 years of rust, would be no evidence whatsoever of your competence to be attempting either approach.
I wasn't meaning to humblebrag or anything. It's just to let anyone replying know that they don't have to fill in every minor detail for me, although details are more than welcome.

Overall I'm just looking for a nudge in the right direction by anyone who may have done something similar, and I should be able to handle the rest. :D

airfry
Posts: 5
Joined: Sat Aug 10, 2019 4:32 pm

Re: Homemade airfryer

Sun Aug 11, 2019 5:40 pm

Welp... It is entirely too tedious to take apart my Philips airfryer, so it looks like I'll need to make my own. (Or worst case scenario, I'll make due with hacking into that Gourmia WiFi airfryer.)

Would anyone be so kind as to guide me in the proper direction so that I don't miss anything? It looks like I'll need the following:
  • Circular turbine-ish metal enclosure to withstand high heat + circulate air
  • Heating element, temperature controlled via PWM?
  • Metal fan to circulate air, directly next to heating element (so it will of course need to be able to withstand the heat as well)
  • Raspi-compatible thermostat?
I wonder if there are any prepackaged standalone thermostats w/ heating elements (and maybe fans too)? It would be nice to have something premade to simply send a signal to. I've been looking on Digikey and the sites listed in this thread: https://www.raspberrypi.org/forums/view ... p?t=197477. Any other sites I might want to look at?

I'm also curious as to the best way to wire everything up to avoid the wiring being exposed to too much heat.
Last edited by airfry on Sun Aug 11, 2019 6:01 pm, edited 1 time in total.

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lpsw
Posts: 157
Joined: Thu Jun 25, 2015 4:45 pm
Location: USA

Re: Homemade airfryer

Sun Aug 11, 2019 5:58 pm

The first step I would take - check with my insurance agent to verify that any personal injury and/or property damage, caused by a DIY high temperature appliance, would be covered.

I already know what my agent would say.
Self-education is, I firmly believe, the only kind of education there is - Isaac Asimov

airfry
Posts: 5
Joined: Sat Aug 10, 2019 4:32 pm

Re: Homemade airfryer

Sun Aug 11, 2019 6:03 pm

lpsw wrote:
Sun Aug 11, 2019 5:58 pm
The first step I would take - check with my insurance agent to verify that any personal injury and/or property damage, caused by a DIY high temperature appliance, would be covered.

I already know what my agent would say.
LOL. I will be taking every precaution to prevent anything stupid.

PhatFil
Posts: 1411
Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: Homemade airfryer

Mon Aug 12, 2019 2:04 am

have fun and keep us posted with your progress and build.. I for one like to follow builds ;)

a few tips based on my own attempts at diy solutions,,

Qmax punches are the best tool for cutting clean holes in materials such as the stainless steel walls of cooking pots for inserting elements/vents/feeds/drains.

silicone rubber baking sheets make ideal doner materials for diy food/heat safe diy washers/gaskets.

card templates wrapped with copious volumes of ptfe plumbers tape (3-4mm thick ,, it traps air and pillows as it builds up) can be used for large or irregular food/heat safe gasket/seal needs and under compression will emulate hard ptfe seals.

If using SSRs to switch Hi load heaters/elements DONT SKIMP ON THE HEATSINK especially if using rapid switching to limit the power via a pid or similar and over spec the amp rating by circa 8-10x

airfry
Posts: 5
Joined: Sat Aug 10, 2019 4:32 pm

Re: Homemade airfryer

Mon Aug 12, 2019 2:20 pm

PhatFil wrote:
Mon Aug 12, 2019 2:04 am
have fun and keep us posted with your progress and build.. I for one like to follow builds ;)

a few tips based on my own attempts at diy solutions,,

Qmax punches are the best tool for cutting clean holes in materials such as the stainless steel walls of cooking pots for inserting elements/vents/feeds/drains.

silicone rubber baking sheets make ideal doner materials for diy food/heat safe diy washers/gaskets.

card templates wrapped with copious volumes of ptfe plumbers tape (3-4mm thick ,, it traps air and pillows as it builds up) can be used for large or irregular food/heat safe gasket/seal needs and under compression will emulate hard ptfe seals.

If using SSRs to switch Hi load heaters/elements DONT SKIMP ON THE HEATSINK especially if using rapid switching to limit the power via a pid or similar and over spec the amp rating by circa 8-10x
Exactly the kind of tips I'm looking for! Thank you!! :D

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