RepRapPro Hotend

When choosing an hotend, I kept the eMaker/RepRapPro Hotend, because it was compact, great, and cheap.

But their design evolved [reprappro.com]

Quote

The stainless barrel and brass nozzle have been combined into a one piece stainless steel nozzle to speed up assembly time.

As I needed more nozzle I ordered 50 parts to make more hotend around this one piece nozzle.
It seemed fine at first, easier for the assembly and perfect to level in dual extrusion setup.

But as we are just starting to use it, we have a little problem, symptoms :

puching filament by hand, ok
starting to extrude, ok
but after some time it get harder, then stop
like if in the short one-piece stainless nozzle, the thermal break is not as good as the two part version and heat ramp up and soften the filament making it harder to extrude.

Maybe on the Huxley/Mendel the geared extruder can cope with it, but with the actual direct drive nema14, we need to find a way to solve this...

Here is a thread to keep a track of reflections.

Solutions :

1) try with the tapered nut because it will place the heater block a little higher (may soften the jam)
2) try to place the heater block at the lowest point possible (to prevent the jam)
3) more cooling ? (better fan to increase the temp gradient)
4) geared extruder ? (small enough to fit in the FoldaRap)

Or, and I think I will go this last option : have the old version manufactured again, because it was great.
For that I bought all the remaining nozzle (03mm) and we will make the stainless steel barrel, I'd even say we will try to have it like in my first eMaker Huxley, without ptfe liner. Because it's still working fine on the FoldaRap#033 where I ported it

---

about // liberapay // flickr // wiki // thingiverse - github

I didn't try to change the heater block position or the cooling (would probably don't change much things), and it was quicker to make a derivate from Andy3D mini-extruder (derivated from the reprappro one)

[www.thingiverse.com]

---

about // liberapay // flickr // wiki // thingiverse - github

Hmm still far from what I'm used to with the two-parts-nozzle, but at least it seems usable with the geared extruder and after having lowered the temps from 205°C to 175°C






(before lowering the tempn the plastic had a "too hot" look with tiny bubbles and not smooth surface)

Video : [www.flickr.com]

---

about // liberapay // flickr // wiki // thingiverse - github

Interesting fact : from the FoldaRap Workshop at the FacLab the other week, a machine is running a one-piece-nozzle, with the normal direct-drive.



We didn't had many time to try it but the oshw logo I usually make as a first print was good.

Bad news, when I tried to repeat the experience on a recenlty build FoldaRap, it didn't worked...
Good news, on another machine finished the day after, it worked !
But on the last one made, it don't : / (or somewhat, but not as great as the two which works)

So for the moment it's a 2-2, and while I was relieved to see it working the first time I'm now more convinced than ever that we need the two-part model made again. We are working on it and ordered a hundred barrels as a start to a local CNC shop we are partnering with

---

about // liberapay // flickr // wiki // thingiverse - github

Hi Emmanuel,
thanks for keeping us informed :-)

Your problems with the new nozzle remember us, if needed, that despite the apparent simplicty hot-end are actualy quite complex.
Do you have any clue or hypothesis why it's working only on some Foldarap ? It's quite an "interesting" situation.

In any case it is a good example of the interest of open hardware :-)

Good luck for the future,
Michaël.

I guess it's all related to the temperature gradient and the viscosity of PLA in the hotend.

The one-piece nozzle is maybe a little short if you compare it to the prusa-nozzle (right on the picture), and despite the cooling block I guess the heat goes up enough to heat the filament sooner than on the two-part design, making it harder to push (while it's not a problem on geared extruders, we were already at the limit of the direct drive nema14 configuration)



Thanks for the encouragements ^^

---

about // liberapay // flickr // wiki // thingiverse - github

Hello, after disassembling about six time the hotend, because of clogging, I found that if I set the fan on, before heating the hotend, it work quite well, if I forgot the fan before heating, it clog.

---

[www.thingiverse.com]

(indeed, don't forget the fan, it's supposed to be always on ^^)