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I'd like to make an oven for curing adhesives that require an elevated temperature for a proper cure. I'd like for the temperature to be settable from 60 degrees C to 75 C plus or minus 5 degrees over time, and over the volume of the container. I'd like for the volume to be about 6" x 6" x 6" or 15 cm x 15 cm x 15 cm.

Primary objectives are to keep the cost down and to make the oven out of easily available materials from home depot or mcmaster carr or similar. Ideally would prefer to repurpose some home appliance. The ideal for me might be just repurposing a toaster and adding a temperature controller to it, but I worry about a toaster having consistent temperature through its volume.

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I like the toaster + PID controller idea. The big challenge to insuring even temperature distribution in the oven is properly insulating the chamber. If the chamber is insulated to minimize temperature change from design discrepancies and thermal "leaks", the PID will eventually figure out the switching. Similar to heat treating ovens/kilns. Just a PID, thermocouple, and heating elements. The 6" or so thick, overlapped, fire brick chamber is what makes it work right. More PID's/thermocouples/heating elements to create more "zones" will increase your level of control too.

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Even distribution of temperature is the worst part of the challenge, and a toaster oven, being a radiative heat source, will irradiate the sides exposed to the heating elements to way higher temperature than the remaining sides. Consider a convection oven or an air fryer instead; it keeps the temperature quite constant throughout the volume.

PID is overkill for this kind of application and risky because it can easily overshoot the control and overheat your adhesive; you should use plain hysteresis control (lower 'on' threshold, higher 'off' threshold) - you might even be able to tweak the bimetallic switch built into the oven/fryer, by tuning it way down (they normally rarely go below 100C.) And you can get after-market air fryers quite cheap.

Depending on time of curing, another good alternative may be a slow-cooker aka crock-pot. Seal your item in a zip-loc bag and immerse in water. It may again need tweaking of the bimetallic switch (they usually operate around 80-90C so you should be able to adjust it easier), and it will provide good several hours of 'cooking' at far lower electricity cost and without the noise convection ovens or air fryers produce. While convection ovens and air fryers come with timers that allow setting up up to about 30 minutes of operation, crock-pots often allow values in range of 8-10 hours.

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you can just put a pot full of water with a thermometer on an oven and adjust the heat to bring the water to a steady 65 c.

Then submerge the adhesive container in it.

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    $\begingroup$ Is the adhesive in a container or already spread over the object? Think possibly it is the second case... $\endgroup$ – Solar Mike Jan 14 '19 at 15:31
  • $\begingroup$ Adhesive is already applied in a few internal parts of the object $\endgroup$ – Evan Jan 14 '19 at 17:56

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