Isothermal Heated Bed - Last Pass

With many thanks to the digital dentist, my go-to bed is borosilicate, with a microscopic waffle pattern of matte black glaze, and was commonly supplied with AnyCubic printers as "UltraBase Pro". It works as intended, with some caveats, but provides a pretty good target for IR guns as regards emissivity (i.e. it's matte black, not transparent).

In any case, the final discussion of the assembly of the vapor chamber heated bed is attached. I used a DS18B20 sensor, lightly coupled with Krytox grease, as a probe, and can confirm that the entire surface is within 0.0625C at 60C. While the DS18B20 may not be wildly accurate in absolute temperature terms, it IS very consistent and sensitive.

For anyone needing a surface that is very consistent in its temperature over a large area, this idea may be of use, you can etch meander heaters into the lower laminate, and remove the upper copper surface completely to reveal a very stiff and flat ceramic loaded material that works very well as a printing surface. It has a glass transition of 285C.

It is imperative that you get all of the air out of the assembly prior to seal off. Also, keep in mind that the entire point of this exercise is that you can apply, say, 500 watts of input to a few square inches of the bottom surface, and expect very consistent spreading of that input to the entire top surface. Almost instantly, like a lid on a boiling pot of water.