Toolhead with Multiple Heat Zones / Hot Ends

  • I am looking to try setting up my super volcano with 2x 40W heater cartridges and 2 thermistors rather then the stock single 80W heater cartridge and thermistor.

    In theory this would allow me to have 2 zones of heat in the hot end, an upper zone and a lower nozzle zone. The upper zone should regulate a higher temperature than the lower zone to help heat the filament faster while the lower heater would regulate a more consistent and lower temperature at the nozzle. For example, I would want to stick to 235C on the lower heater while running 260C+ on the upper heater.

    This may or may not work, but IMO, it's worth trying. The first issue that comes to mind is the 2 heaters will fight each other. The upper will run more because of the higher temperature, and cause the lower to run run less, but under load, the lower should increase power to maintain the nozzle temperature.

    Second to this would be multiple hot ends in series with heat breaks separating the heat blocks slightly in order to get true multiple zones, But still requires multiple heaters on a toolhead. For example, adding a V6 after the Super Volcano.

    While I understand the physical connection of this to my 6HC, Im not exactly sure how I would configure the firmware to control this. Im even less sure of how I would tune something like this as the heaters would always fight each other and both heaters would need to tune at the same time.

    Im interested in hearing others thoughts on this and if Im just totally crazy. 🙃

  • @adamj12b I've done an awful lot of work on various experimental hot ends and I can tell you that you won't get that sort of temperature gradient unless you put a heat break or insulator between the two zones. Or possibly, use a metal which is a poor thermal conductor such as mild steel but that will give you all sorts of other problems. Even then, you might need to actively cool the lower section. But if the melt chamber is made from aluminium or copper alloy (which it should be) then thermal conduction will ensure that you won't have 25 deg C temperature gradient, even if the heater only extends to the upper half of length of the hot end. So if you heat the upper section to 260, then I'd be very surprised if you even see a temperature as low as 255 in the lower section.

  • What benefit are you looking for?

    Its possible to build a hotend with a many thermal zones as you want. Gets a bit complicated to assemble, plus it gets very expensive fast.

    But what benefit do you think you'll get from that cooler nozzle?
    Because having wildly different temps in the zones just increases the risk of boiling the polymer when the dwell time is too long.
    Plus when extruding at a high rate, that polymer flow is going to equalise the temps quite quickly.

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