Prusa Mendel printbed

I put together a heated printbed for my Reprap using three parallel 10 Ω 100 W power resistors. The resistors are screwed onto a 220 mm x 200 mm x 5 mm aluminum sheet. This will make the whole printbed a 3.3 Ω 300 W heating element.

Printbed power resistors
Three 100 W power resistors connected in parallel will act as a heating element.

On top of the sheet I will place a 220 mm x 220 mm sheet of glass to use as a print surface.

Top of printbed plate
Top of printbed plate

When printing the printbed should be between 60° C and 110° C depending on which plastic is used.

Since the main voltage used on the reprap is 12 V, maximum power that can be achieved is

\frac{U^2}{R} = \frac{12^2}{3.3} = 44 W

My guess is that it will take at least two eternities before it gets hot enough, but for a start I’ll use the printbed temperature logic built into the RAMPS controller card.

Later on I think I’ll build my own temperature controller with either a step-up or a separate power source with a higher voltage to get more power out of the printbed.