It has been a problem to heat the whole object without a heating chamber.

What about infrared heat lamp etc?

Placed on both sides one should be able to focus the heat coming from the lamp just right so that there would be no warping..?

Possible yes, but worth trying?

... with IR-heaters the amount of heat absorbed by the plastic is dependant of the colour and mass, so you have to adjust the temperature for every job and during print.

An enclosure heated from outside with heater barrels or resistors is much easier to build - look here (in the attached image) for some other heaters: [forums.reprap.org]

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]