Mastering Oven Control: Precision Resin Curing with DIY Modifications - How Hard Can It Be?
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- čas přidán 12. 07. 2024
- Toaster ovens can be bought cheap and repurposed for curing resins, reflow soldering, and more. Katie picked one up, but found that it wasn’t very accurate when it came to reporting its temperature during cooking. Not ideal when you want to be precise!
She wanted to fix that, so how hard could it be to make a Raspberry Pi Pico-based oven temperature controller with a K-type thermocouple and a relay? Find out in this episode!
Discuss Katie's project and ask her questions on the element14 Community! bit.ly/3OHEsqt
Engage with the element14 presents team on the element14 Community - suggest builds, find project files, and see behind the scenes video: bit.ly/3tmdewv
Visit the element14 Community for more great activities and free hardware: bit.ly/3q6YMpu
Tech Spotlights: bit.ly/3qPrDhM
RoadTest and Reviews: bit.ly/3pV5Bux
Project14: bit.ly/31wbnJY
#0:00 Welcome to element14 presents
#0:18 Overview
#1:52 First Steps
#10:00 Let's Get Soldering!
#10:45 Buttoning Up the Case
#15:52 Give Your Feedback
#raspberrypi #raspberrypipico #raspberrypiprojects #raspberry_pi #toasteroven - Věda a technologie
Nice project! :D I made something similar years ago, but used an off-the-shelf PID controller. I used it for curing resins, drying paints, driving off solvents and so on.
For cutting apertures I just drill out and cut close, then spend a LOT of time filing out to dimension :O You could also make a bezel from thin aluminium sheet and cut an aperture in that :D
That’s great, thanks for sharing 👍
Cheers Katie ! Really well put together project, and one I have been looking for for ages. I have had an Aldi oven in my shed for years I picked up from a second hand shop. Now I have no excuse ! I'll be honest, I haven't looked at Element 14 since Ben left, but you have got me watching again. Thanks :)
To create a nice clean opening in a casing. I use a paint marker that can be easily wiped of so it doesn't leave a stain on the surface. I mark out the area I want to cut out as precisely as possible and then I cut out the opening smaller then needed by about 0.5~1 mm. Finally I use a file to get to the exact desired dimensions and to make the edge or the cutout nice and smooth I just use some fine sandpaper. It takes a while but the result is well worth it 🙂
The paint pen is a great idea, I've been using a tippex pen, which gets messy, so might try a paint pen instead.
I did mark it with the tippex, and then cut it, but I am probably a bit impatient and just hack away with a dremel, I should probably finish by hand with a file and sandpaper to get a better finish.
Cool project, and I'm already thinking how these techniques might be used to control other hardware. Nice!
I'm hoping it'll be a super useful tool
Even though I didn't understand what the hell was going on here, I still loved watching your presentation of this. Thank you!
Great stuff - thank you!
Nice video. In my experience even decent ovens tend to fail temperature control HARD when below 100 celsius. They assume your cooking happens in the range 100-250 degree and kalibrere/build for that range.
Our kitchen oven is actually really good at lower temperatures, will go down to 40oC, but it's a fairly nice model, and does that for bread proving mode. I don't really want to put chemicals or glues in it though, so this was my solution.
One trick when using a kitchen oven to dry 3D printing filament is to turn on the oven light, it provides just enough heat to get it done. Or if you have an oven dedicated for that use, run a 240V oven on 120V.
I love this!
Great work Katie. It would be great to know how you go using it, including reflowing.
I'm going to give reflow a go with the project after my current one, so keep an eye out for that one!
if you can't cut a clean hole with the tools you have, cut a rough hole and 3d print a bezel to make it nice.
I think a 3D printed bezel would be super useful. I've used this model of screen on several projects now, so sure I'll use it on more in the future, so will put it on my todo list to design!
Great project, thanks for sharing with Us!
Hi, great project. To cut openings in my projects I have used nibblers, though this not always practical because the case may be too small.
nibblers sound useful, have you got any recommendations for ones to look for?
@@hifromkatie Yes, I have two tools, the one I would recommend is Klein Tools, part no. 76011B. It is slightly smaller and can get into smaller cases.
nice idea! For displays cutouts in metal without a cnc machine, i always made a mess of it. What i do now: cut it oversized in any way i can (drilll holes, file, jigsaw,etc), and then just 3d print a nice looking bezel that has a width that covers all my 'crimes' ;) For most standard sizes you can also get ready made ones for a few cents.
thats a very handy trick!
Great job on this project... Reminds me of the Silicon Chip / EPE Mag 'PCB Reflow Oven' project of a few years ago...
The element doesn't *instantly* cool when the power to it is cut, so even though it's turned off its thermal mass will keep heating the oven for a little while. That's one reason for the overshoot. One way to combat that would be to completely change the behaviour when it gets to ~10 below the target temp and rather than having the element constantly on start doing short cycles of on and off. I do think that some trial and error to get some data (or a "profile" as you called it) so you can get a better idea of exactly how to program it.
I think the critical bits of info are the rate of temperature rise while the element is on (which isn't necessarily constant across the working temperature range) and how long the oven temperature continues to rise after the element is turned off.
The more I think about it, the more complex a problem I think it is to get a really reliable, constant temperature. You have to balance several factors including the rate you're putting energy into the system, the rate of energy loss (an uninsulated toaster oven doesn't retain heat efficiently), and the factors that cause overshoot such as the elements' thermal mass and sensor reading lag.
But, it might not actually be that difficult a problem given some careful thought. I think the biggest factor is to work out a "duty cycle" profile where the cycles get shorter as you approach the target temperature, understanding that there will be a minimum on time of several seconds, and the off time will be longer than the on time because the element heats up faster than it cools. But the thermal mass of the element will have less of an impact with the longer duty cycles and more and more of an impact as the cycles get shorter. As a wild guess, I would start with a maximum on time of 20 seconds with an off time about the same when it gets to 10 degrees below the target, ramping to about 5 seconds on and 10 off when it's within about 2 degrees of the target. Depending on how well (or poorly!) that works, I would then fine-tune the duty cycle range until it gets a satisfactory result.
I assume that the reason you used an external enclosure was to avoid all the possible issues that could be caused by putting the circuits and components inside the high temperature environment of the oven's enclosure, which is a really valid approach.
I like using a sharp razor blade cutter tool with a metal straight edge, very carefully, going over and over the lines for the cut outs that are plastic. Have something solid like a piece of wood behind where you are cutting as well. You can mark and punch then drill the corners with a twist drill first before cutting if you want more rounded. Hole saws are handy as well, though then I wind up using the blade in a more rocking motion that isn't so safe where I've actually had the hole saw cut up my thumb and index finger one time due to me holding the piece when drilling out. Thankfully no issues with a razor blade cutter, though have with a deburring tool again holding with my hand not carefully and that time the part wasn't against a surface. For metal, I usually use a Dremel or similar style tool with cut off disc. Though a handy tool that is slow and sometimes jambs is the hand held nibbler tool. That makes better looking cuts when careful, though sucks donkey bum when gets jammed.
Oh and I forgot to mention, using painters or masking tape over the whole surface for a cleaner markup and final surface.
I used to wonder why precision lab ovens were so very expensive, and now have a better appreciation for what is involved. BTW, as far as I know, all thermosets will benefit from a nice post-cure.
you could use P.I.D for the temperature control.
How hard could it be? LOL. I have been wanting to do something like this myself so I like this video quite a bit. Also, a word of caution on epoxy: when it gets hot prior to cure, it also tends to get thin and runny. Often it might be better to use a more modest temperature for at least an hour or so to get an initial set before going all the way up to 80 C. Also, ovens usually have some type of over-temp cutoff in series with the heating element. I couldn't tell if you kept that. But it would be a good practice to do so in case the relay fails short or something.
Attach a metal cookie cutter to an old soldering iron. It'll melt a perfect hole in whatever shape you want. You could probably bend a metal food can into a rectangle shape as well.
I once had a kit to refill laser printer toner cartridges and it came with one of those to make the fill hole.
I can see a PID (proportional-integral-derivative) controller in your future.
Me too!
good work. and nice project. but katie, why do you always seem so scared and nervous? you always do a great job is all your videos. so don't worry and keep up the good work :)
I have this oven and the first time I turned it on it smelled so bad I ended up running it outside, I dont know what happened but if anyone else buys it maybe do that first.