Beginner needing help with Bed Temperature and Power Supply Electronics

[jumi1174]

Hi there

I've recently purchased and completed building the Prusa i3v 10". It's my first personal 3D printer, and I love everything about it so far.

I have a couple questions:
1) When printing ABS, the bed starts at 110 °C but after the first couple layers, the bed drops in temperature to around 70 °C. Is this normal? My ABS prints are having issues sticking to the bed, and I'm wondering if this may be part of the issue.

2) What's the safest way to install a power switch to work with the 12V/30A power supply? I don't want to accidentally fry any of the electronics, but I don't want to have to keep plugging and unplugging the power supply from the wall when I use the printer.

3) Is 10 awg wire too thick to wire FROM the power supply to the necessary inputs on the printer electronics?

Thanks in advance!

[JimG]

1) When printing ABS, the bed starts at 110 °C but after the first couple layers, the bed drops in temperature to around 70 °C. Is this normal? My ABS prints are having issues sticking to the bed, and I'm wondering if this may be part of the issue.

Check the settings in slic3r (or whatever slicing software you are using). Dropping the bed temp to 70C after the first layer, in my experience, will cause ABS prints to lift 100% of the time.

2) What's the safest way to install a power switch to work with the 12V/30A power supply? I don't want to accidentally fry any of the electronics, but I don't want to have to keep plugging and unplugging the power supply from the wall when I use the printer.

Not sure about "safest", but here is how I did it:

1. Locate a spare PC power cord. Use diagonal cutters to snip off the female end.
2. Strip the wires in the cord (white, black, green) and crimp on #6 or #8 ring connectors. Use a real crimper, not pliers!
3. Connect the ring terminals to your power supply (black to "line", white to "neutral", green to "ground").
4. Plug the cord into a switched outlet strip and use its switch to power on/off.

3) Is 10 awg wire too thick to wire FROM the power supply to the necessary inputs on the printer electronics?

10 AWG is pretty thick! I used 14AWG super-flexible silicone insulated wire and am pleased with the performance. I would guess 12AWG would fit in the RAMPS terminals, too. Not sure about 10AWG, though.

If you decide to use heavier wire on the leads to the bed heater, be aware that soldering wire this heavy to the PCB will be very challenging.

Jim

[AbuMaia]

I'm pretty sure my 12v/30A switch isn't safe, but it's complicated. Same as above, I used a spare computer power cord, cut off the female end, stripped the wires. I used fork terminals, not ring, but otherwise the same. I connected a fuse to the black wire coming out of the cord, connected the other end to the common terminal of a SPDT switch. NC of the switch was connected to the NO of a relay, and the switch NO connected to the relay NC. Then the relay common was connected to the line terminal on the power supply.

This allows me to power on/off the printer via relay, switch, or both, just like dual light switches in a hallway or staircase.

[printbus]

3) Is 10 awg wire too thick to wire FROM the power supply to the necessary inputs on the printer electronics?

There's no reason to be running 10 AWG from the power supply to the RAMPS board if that's what you mean. The i3v-10 has to have a relay wired in for the heat bed, so the other wires going to RAMPS only need to carry about 5 amps. #16 or #18 is OK for that.

[jumi1174]

Thanks for the replies everyone! Prints are sticking to bed now!