heater cartridge wiring gauge

gnydick

looking at the docs for the toolboard 1LC, it says the heater can sustain up to 5A. Figuring 24V and 5A would yield 120w. I want to hook up an 80w heater I have but the wire guage is much too large. What am I missing here?

gloomyandy

@gnydick What heater are you using? If it has a particularly heavy set of wires attached to it I'd be checking that it is actually 24V 80W and not 12V 80W. Other than that I'm not really sure what question you are asking. It may be that the heater designers are expecting a long cable run and so have chosen a heavier gauge of wire, but that is probably a question for them.

gnydick

@gloomyandy it's the 80w heater that can be ordered from Luke's Lab for the Chube hot end. I'm running the air cooled so it uses the 6x20 cartridge, not the super volcano length.

What I'm asking is, is that normal? If it's that large for 80w, how could a 120w ever fit, etc.

droftarts

@gnydick What gauge is the wire? Is it too big for the ferrules, or too big for the screw terminals of OUT0? In https://docs.duet3d.com/Duet3D_hardware/Duet_3_family/Duet_3_Toolboard_1LC#wiring-notes we say

Screw terminals: These are not high current so fitting the wires directly into the screw terminals is fine. Using small ferrules is also fine; Duet3D supply 0.5mm^2 white ferrules.

EDIT: Is it these? https://lukeslabonline.com/collections/general-3d-printer-parts/products/high-wattage-heater
They say 18 gauge wire, which is 1mm diameter or 0.823mm^2. So won't fit in the supplied ferrule, but should easily fit in the screw terminal, even with a larger ferrule.

Ian

gnydick

@droftarts, yes, exactly. I couldn't even get the strands in a ferrule that would fit.

Originally, I tried just reducing the conductor count but that caused the wires to get hot to the touch and the toolboard's mcu was over 100deg C.

So I ended up making a step-down connector that reduces the diameter. basically additional high temp heater cord spliced in and fit in the ferrule.

It's working better now. The MCU is only 64 deg and nothing is hot to the touch.