This is the Aluhotend in it's most current format currently it is a 5 piece design:
Heatsink - all of these are manufactured with a M6 threaded hole right through the centre of the heatsink. The mounting point is dimensionally identical to the [jhead] and should mount in anything the [jhead] does.
Thermal Barrier - these have taken a few forms before this one. Most of them have been turned and reduced in diameter from the outside leaving no room for a PTFE liner. With the latest version, the thermal barrier is a 35mm length of stainless steel threaded rod with a hole bored through it at 4mm, then either a 2mmID 4mmOD or a 3.15mmID 4mmOD PTFE tube is inserted. The advantage with this configuration is that not only is the liner held captive by the heatsink, the large diameter on the thermal barrier provides a great deal of strength and protects against crashes into the bed which would cause damage to previous versions.
Heater Block - the current design is made in a CNC shop. It has 5 holes, 2 of them are threaded. The M3 threaded hole takes an M$ capscrew for clamping a heater cartridge or a resistor in the 6mm hole. The holes for the thermistor are 2mm, 2.5mm and a M3 threaded hole which allows the use of a through hole type of thermistor. The reasons behind this were mainly safety, the thermistor cannot physically fall out leaving the hotend to overheat. It can accommodate the common bead type thermistor used with the jhead or a screw type thermistor can go in the M3 threaded hole.
Nozzle - the nozzle is a fairly standard M6 threaded nozzle, with the current version (v7) using a modified Ultimaker nozzle. They are drilled out at the back to 4mm to accommodate the PTFE liner going down into the nozzle. This also seals up the joint between the nozzle and thermal barrier.
1 - screw thermal barrier into heatsink
2 - screw nozzle into heater block all the way
3 - insert ptfe liner into thermal barrier cut off with about 6mm remaining on the end
4 - screw thermal barrier into heaterblock until it hits the nozzle (todo: insert pictures here)
5 - back off nozzle by 1/2 turn (todo: insert pictures here)
6 - tighten thermal barrier by 1/4turn (todo: insert pictures here)
7 - tighten nozzle against thermal barrier
when completed your nozzle should be pressed against the heaterblock, if there is a small gap try again
Wiring it up
is simply the reverse of assembly however if the hotend has been used it is advised to do it while it is hot otherwise the nozzle can potentially be damaged
disassembly is not really unless absolutly nessessary recommended , ideally you should run a filament cleaner to avoid blockages.
can be used normally just like most other hotends, one suggestion for easy feeding especially with 3mm filament is to cut the filament at an angle so that the pointy end wants the curl into the middle of the tubing, this will allow the filament to slide all the way down instead of a 90 degree curly end digging into the PTFE liner, this is somthing that should be done on any PTFE lined hotend to maintain the integrity of the PTFE liner and make it last as long as possible
swapping plastic and colors can be done simply by backing out the filament being used and loading the next up to 50mm of plastic should be pushed through the hotend preferably by hand to purge the old plastic out.
The temperature limit is about 245 C if fitted with an internal PTFE sleeve. It is highly recommend that a filament cleaner is used with any hotend, in the event of a blockage unblocking can be done with the pull method or with a 0.4mm drillbit
Standards of Filament
there are no particular standards for filament and each manufacturer seems to be different, in the early all metal hotends v1 and v2 some colors exhibited more back pressure than others which is why the ptfe liner was introduced at the time some colors like the florescent yellow would only run for a short time before jamming where as black and other colrs would run for months continuously with no issues, generally you want to run the best filament you can afford to run, for development purposes these hotends are tested in a production environment on filament which is in the lower part of the quality spectrum.
Cooling on this hotend is and has always been rather simple all of the setups i have built and tested this hotend with have been in the opposing fan configuration this setup allows both the cooling of the hotend and also the part , it also has the added benefit of redundancy if one fan fails during a print you still have one running see below as an example however it will function just fine on one.
|3D industries Australia||Australia||link||-|
the images below are somewhat out of date, as of 30th july dxf sources are available on my github https://github.com/jgrjgr/Aluhotend nozzle:
Internal hole depths: 2mm hole depth: this value determines the length of the orifice, ideally the orifice length should be about 0.5mm calculate this based on your drill type,
the 3.5mm hole is 7mm deep any less and it no longer becomes a compatible replacement for the up! nozzles,
- this value is likely to change in the future and we may have to make up different nozzles, for different hotends eg highspeed and retractionless,
This Hot End is mounted to the extruder Cold End using a standard Groove_Mount.
Videos and testing
<videoflash type="youtube">QcRHd9Gh5Q0</videoflash> <videoflash type="youtube">y4gk3yjslwU</videoflash>