Reprap hot-end

Initially, I was going to order a Makergear hot-end from the US, but - at approx. 90 euro after postage - it was quite expensive for a hot-end alone (i.e. not including the rest of the extruder) so I changed my mind and resolved to at least try to build one myself. I could have sourced cheaper hot-ends from somewhere in Europe, but I had already acquired the rest of the extruder parts at this stage - and thus limited my choices of hot-end.

The hot-end I have at the moment is based more-or-less on the hot-end which Adrian Bowyer designed for the "Reprap universal mini-extruder": http://reprap.org/wiki/RepRap_Universal_Mini_Extruder . Mine is basically a simplified version - but the dimensions are approximately the same. I used PTFE rod as a thermal insulator and brass for the heater block. The power resistor is a 6.8 ohm vitreous type, and is held in place using car exhaust putty. I used bootlace ferrules to crimp the resistor leads to their wires - and insulated the connections with heatshrink. (The insulation is very important as otherwise the resistor leads can be shorted by the heater block). This is all in accordance with Adrian's design - I claim no originality in this regard.

I don't have a lathe, so used a mounted power-drill to turn down the diameter of the brass and PTFE rod. (Specifically, this involves mounting the power-drill in a stand, and using the drill chuck as a makeshift work-holder. I used a file rather than a chisel. This is similar to the "Afghan lathe" technique described by Vik Olivier, but slightly different.)

Drilling the .5mm hole in the melt chamber was quite difficult. I had initially hoped to use a smaller diameter, and tried .35mm, .4mm, etc. - but the drill bits broke in the process. Even the .5mm bit ended up warping.

Having said all of this, I have yet to test the hot-end properly - and might end up buying one pre-made after all.

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