The mechanics were bolted, glued and zip-tied together, the headers of Rostock-Marlin somewhat configured for the dimensions of my RoStrap, pronterface was able to issue some commands (move to X/Y/Z, extrude) and read the temperature back…
…time to try a first print!
!?
OK, trying to print PLA on Kapton tape, that has not even been glued wet, was not a good idea. And the metal plate seemed to be flat enough, but it’s quite cold – so let’s do something else.
As I did not have adjustable end-stops, I tried to tilt the “platform” (cork table mat, “base plate” see below). But next the PLA jammed.
Filament grinding is always an issue with these direct drive bowden extruders – even with 1.75 mm filament. Additionally I had ordered my hot end too cheap – http://airtripper.com/1236/j-head-mk-iv-hot-end-clone-design-quick-review/ sums up, what can go wrong, when you just buy any hot end on eBay.
Furthermore: IMHO the PTFE liner tube thing is a design flaw. Period. [*]
Moreover: in my installation the filament was not guided properly. http://www.themgames.net/j-head-conversion-to-1-75-mm/ gave me some hints, so I tried to improve this point wit a “sharpened” tube running through the whole PEEK insulator.
Afterwards I was actually able to have the PLA squeezed out of the nozzle in a controlled manner!
Somewhere I read that Lexan or Makrolon was a suitable substrate…
…but although the speed was still slow there was a considerable amunt of force needed to feed the material. The feeder motor got hot enough to just fold the (softened) filament.
Having overclocked plenty of PCs in the past I coose to keep a high current running through the motor windings an getting rid of the heat afterwards:
“Baking” as well as lubricating the PLA were on the agenda afterwards. To no avail. I had to da something about the nozzle. Back then I had not heard about the atomic / cold pull method (http://support.3dverkstan.se/article/10-the)…
[*] Update, after my experiences in 2018 with the TronXY X5S: Nowadays it is absolutely possible, to run down the bowden tube to the nozzle – E3D did a nice wrtiteup, when they released the “Lite6 HotEnd”.
Basically the effective melt zone gets smaller (compared to a “Full Metal” version with stainless steel HeatBreak), but PLA won’t jam in there. Thus it’s also less likely, that you have trouble with China clones, because there are less critical surfaces inside your hot end for them to polish. 😉
I still don’t understand, why there are “hybrids” with the 4mm OD / 2mm ID bowden tube running to the heat break and then a (3mm OD) PTFE tube inside the heat break – that way you get all the drawbacks without any benefit…
burningbecks 