I finally completed the heater bed for my Series 1.
- A piece of 1/4″ cut aluminum.
- 36 X .22 ohm resistors in series.
- An ATX power supply with 20 watts on the 12 volt rail.
- Benchtop Power Board from Sparkfun. https://www.sparkfun.com/products/9774
- An Ohm meter that reads temperature.
From this, I got a working heated print bed.
However, the bed strained to reach 30° C. For the golden grail of ABS plastic I’d need 80° C. So, I got an additional ATX power supply, this one with 17 watts on 12 volts, I split up the series of resistors to 1 group of 20 for the 20 watt psu, and a group of 16 for the 17 watt psu. That’s as close to evenly distributed as I can get. About 1 watt per resistor.
Now it strains to reach 50° C. Progress, but not quite there. I do have a third power supply. My next step it to bring that into the mix. Right now I’ll have to be satisfied with what I have because I only have 2 Benchtop Power Boards. (One borrowed from a friend.)
To compensate, I’ve covered the board with klapton tape and a slurry of waste ABS material dissolved in acetone.
Here’s a print of a rhino vase, I downloaded from thingiverse:
It printed remarkably well. Gcode by Kisslicer. Only problem I had was that the infill was too sparse and the skin thickness was too thin. You can’t see it, I’m now showing it to you in the picture, but on the other side there’s a crack where the layer’s came apart.
Still, for a first try, I’m satisfied. Then to get it right, I went back into Kisslicer and thickened up the inner supports. I changed the skin thickness from 1mm to 2.5mm, and changed the infill to 12.5%. This is what I got on the 2nd run:
The supports were too flimsy from the start. This is something I hadn’t changed from the first to second runs. The ABS started warping with an hour. I thought I could still salvage the job and let it continue. This is after about 10 hours of printing.
That’s all for now. Heed the lessons learned.
Oh, btw this is where I got the inspiration for the resistor-driven heated bed:
This man built his 3d printer from scratch. Everything!