I’ve ‘installed’ a heated print bed – its 4x 2.2 ohm resistors wired as [(2 in parallel) in series with (2 in parallel)] giving 2.2 ohms. This gives ~5.46 Amps and ~65 Watts @ 12 Volts which heats the bed to 55C (dibond underside) in a few minutes (I haven’t timed it!). Its driven from an old atx pc power supply with a max of 6 A @ 12 V and I’m using RAMPS to drive a relay to control it (my main atx gives 15 A @ 12 V but the printbed trips it out). Hopefully the relay will survive….
The first tests, some shamrock i designed for my children to paint for St. Patrick’s Day, came out pretty good:
Here is an image of some 20x20x10mm ‘cubes’:
The one on the left is 100% fill @ 6 mm/s, WoT of 1.8 and layer height of 0.25 mm. It seems to be well filled, possibly bordering on overdone. The one on the right is the same at 20% fill. The top surface is pretty good but the light scatter from layers below makes it look bit worse. The next thing to do is print a few different sized cubes to check the dimensions in case there’s backlash present. Then I an hopefully move onto printing Prusa parts….
Here’s the latest image of the repstrap contraption: