Hey everyone,
I recently built my own DIY hotplate stirrer using a 2000W iron base and PID controller (pic attached). I’m really proud of the build, the magnetic stirring works flawlessly, and the PID locks the plate temperature perfectly.
But I’ve run into a massive heat transfer wall and I’m losing my mind.
My hotplate reaches 250°C with zero problems. I put my oil bath (in a 1.8mm thick aluminum pot) on top of it. After waiting for what feels like an eternity, the oil bath is barely hitting 70°C, and the liquid in my flask is sitting at 60°C.
To be completely honest, I’ve never owned a professional lab hotplate before. Because of that, I’m not really familiar with standard heating curves or how long it should take to heat up a mass like this. A part of me thought, "Maybe this is just how hotplates work?" but 250°C to 70°C delta feels physically wrong.
I absolutely don't like dirty solutions. I know some people suggest using a sand bath, but I really don't want to scratch my expensive glassware. I also don't want to smear thermal paste or oil between the hotplate and the pot because I want to keep my setup clean.
So, experienced lab rats and DIYers, how do you fix this? Any advice would be massively appreciated before I throw this thing out the window.
A quick disclaimer to preempt the safety police: Yes, I am aware that parts of the chassis are MDF and I am using a brushed motor. I am fully aware of the potential spark/fire risks. I operate under strict safety precautions, monitor the system constantly, and I mostly work with high-flashpoint/hard-to-ignite organics. Please spare me the condescending "you shouldn't be doing chemistry" lectures, I'm strictly looking for heat transfer advice here.
Thanks.
