Monday, 26 November 2012

All Metal Hotend

After my thermister fell outof it's little hole and fooling my arduino into thinking my hotend was still at room temperature, i now have 1 roasted jhead mk2,sadly unusable now but i may revive it later with a new peek body,

for those who haven't roasted one of these the first giveaway is the smell, it's not only rather uncomfortable but it lingers .. FOR DAYS  and i'm not too sure the gas given off is good for your health. so i set off the build a new hotend, i have been down the path of the PTFE and brass barrel arrangement,  this worked fairly well but there are limitations to it one of the being that the meltzone isn't static and that the design is prone to leakage and failure at the most opertune time one of them being towards the end of a very long print.

the main problem i had with this design was that the ptfe rod would swell up and either leak or the barrel would just get pushed out,

so i set out to build somthing a little more reliable and after a little research into the topic an all metal hot end was needed, that way there is nothing to soften and cause a problem.

this is the first iteration:
i replaced the brass barrel with a stainless steel one and made up an aluminium mounting piece for the cold end, remarkably even with no active cooling (a fan) and even though the cold end actually got rather hot enough to burn flesh it was very successful at extruding 1.75mm abs so much so i printed a new direct drive extruder body for it:
i wanted to extrude PLA as well so i had a few changes and experiments along the way to what is today i call the ALUHOTENDV1

the last picture is the final V1 version during winter i had it extruding pla and abs quite reliably with no active cooling for hours at a time, however recently as summer has set in extruding pla is a bit of a different story without a fan, the cold end is 16mm in diameter and the groove at the top matches that of the Jhead so it fits in any Jhead mount, the total length is 80mm and the length of the heater block is 35mm,

2 of the main concerns people have had:
1 - the strength of the thins stainless steel section
2- the orientation of the heater block

as i hear it the first concern stems from peoples experiences with the arcol hotend which have a habbit of breaking so to solve that problem:

you can see the hotend mounted in the vice with the plastic bags hanging off the nozzle,  there is about 4.5kg of water in those two bottles hanging off the end of it, well and truely more than what it is likely to be subjected to on any 3d printer,

concern 2, with the orientation of the heater, the reason for mounting the heater block in such a way is really one of convenience and also heating concerns i don't think it would make much of a difference with the heating resistor mounted the other way, if anything worse

after months of testing this hotend, 1.75mm ABS will extrude really well with of without a fan
1.75mm pla is another story you will need a fan and it's dependant on the type of pla you have, there is a lot of pla out that has been blended with other plastics and is sold as pla and behaves differently,

ultimately if you are running at the correct temperature this hotend will extrude pla and keep it solid right down to the meltzone, like with any hotend if you extrude your pla too hot it will swell and jam up

this hotend is now up for sale at

and on ebay (search for ALUHOTEND)

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