A few Hotends


Here are a few hotends i have lying around,. While i obviously use the Merlin most, i also employ the Hexagon sometimes.

I haven’t come around to actually using the E3D yet, though i did some extruder designs for it. The Prusa hotend will very likely remain unused till the end of time 🙂


  1. Hi Mate,

    I’m considering building an Ultimaker-themed printer – with aluminum extrusion frame, 300×200 heated bed, a bowden extrude, 1.75mm filament aimed primarily at ABS printing.

    I’m considering closing the sides to make it into a heat chamber and leaving the top open. A crossflow fan is to provide an aircurtain both to trap the heat inside and to cool the hot/cold end. I plan to have no fans other than a crossflow fan.

    I’m also quite afraid of fire hazards so I’m trying to find a design with as much metal and as little plastic close to the hotend as possible.

    Could I ask for an advice on strengthes/weaknesses of the hot ends that you have tried? These merlin hotends they are produced ready made somewhere right? (I’m extremely scared of the prospect of RTD/thermistor falling off the hot end btw..) The hotends where PTFE doesn’t go all the way to heat block don’t really work do they? Why do you use hexagon?


  2. bmarl

    2016-02-22 at 19:57

    My experience with different hotends is quite limited since i created the Merlin out of desperation because no good hotends were available to me at that time. Apart from the Merlin it was basically only the Hexagon that i used to any noticable degree. Like the old E3D the Hexagon is a full metal hotend, created to allow printing temperatures in the range >260°C. Full metal has the disadvantage of posing problems with materials like PLA or sometimes PETG that stick very good to polished metal. In your case it should make no difference since ABS works fine with hotends that use either PTFE or are full metal.
    Afaik by far the most hotends come unassembled, i know this to be the case for the E3D, the Merlin and the Hexagon. You need to follow procedure to the letter to make them work correctly since even small deviations can make the difference between success and total failure.
    As far as the mounting of the thermistor goes, yes it needs to be done properly to avoid dangerous mistakes. E3D solves this by screwing it to the heater block, i prefer to glue it in with high temperature cement, something like this:
    The reason why i prefer to glue is simple, if you make any small mistake when screwing it in, or mounting it in any “hard” mechanical way, it can be damaged easily and finding and solving thermistor errors have cost me many days over the years. Glueing them in creates less stress.
    Regarding fire hazard, one step i do is using a high temperature silicone sleave over the heater block. It reduces the risk of burned fingers etc. and can hold a runaway heater for that bit of time longer it takes you to take action. I am currently redesigning my extruder so the parts close to the heater block are made of polycarbonate, which is usually not flamable. I have yet to have any hotend catch fire though, this is just a precaution, not something born out of neccesity.
    For your purpose all three hotends mentioned should do the job just fine.
    The reason for using the Hexagon is easy, it was given to me for testing and since it worked i used it 🙂

    Some words on your printer housing. I fear you will discover that the crossflow will not be enough to keep the heat in. A lso you need less temperature than you mught expect, for me 50°C do the trick easily, often enough 30°C – 40°C are sufficient as well, depending on the size of the object and the exact material. In general modern ABS filament is much easier to print than the stuff from three or more years ago.
    Good luck 🙂

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