Slow getting to 110C bed target on 10" i3v

[printbus]

The heater lead wires are only 18 AWG, which is really too small. I probably will solder in one or more parallel leads. I think replacing with a single heavier gauge wire might cause it not tolerate the movements?

The thermistor readings are good. During my build, I stuck a fine wire type T TC on the underside of the bed to use for confirmation of the thermistor readings. The TC responds much faster to the heater, but always reads within 4C of the LCD display.

Jim

Oh, man. 18 gauge is definitely too small IMO. What I've recommended a few times is check into your local R/C hobby store and ask if they have silicone wire. It's ideal for the bed wires that are subjected to a lot of flex. The silicone insulation is more flexible than the standard PVC jacket, and the wire is made up of a significantly larger number of finer strands that will keep it highly flexible. One source says, for example, that their 12-gauge silicone wire consists of 680 strands. Some neighborhood R/C stores and online places sell it by the foot, so you only have to buy what you need. It can be pricey if you have to buy a prepackaged amount like 10 feet and only need a couple.

I've also suggested, simply for good measure, that once the size for the wire to the heat bed is chosen, use the next larger gauge wire for the fixed wire between the heat bed relay and the power supply. Like you said, it's also possible to double up on smaller gauge wires. There's nothing wrong with that other than the increased bulk of the extra insulation.

Now I'm wondering if my heat bed might have actually had 18-gauge wires before I swapped them out with some of the silicone stuff I had on hand.

If you have the chance, measure the voltage at the bed itself so we can calculate how much power the bed is actually getting.

[JimG]

...What I've recommended a few times is check into your local R/C hobby store and ask if they have silicone wire...

...If you have the chance, measure the voltage at the bed itself so we can calculate how much power the bed is actually getting...

I've got some 14AWG R/C wire on the way. I thought the 14AWG would be a little more flexible, plus I don't have any crimp fittings or ferrules that will fit the 12AWG.

Plus, I think I will just run the GND wire direct to the PSU from the heater. The relay board only switches one side of the circuit. That will save a few feet of wire run.

When I make the changeover I will try and remember to take a few voltage readings. The solder joint where the lead wires connect is hard to get to without a disassembly.

Jim

Jim