Question Dragon hotend poor performance

[stevereno30]

Does anyone know what could be preventing my Dragon hot end from extruding to its potential? Printing with ABS, I get significant die swell and my Galileo2 can only push 93 of the requested 100mm when extruding into open air at 10 mm³/s. Brand new nozzles don't help, and it still cannot push the full 100mm when printing 20°C above the ABS' max print temp. Without a hotend mounted, my extruder pushes exactly 100mm when I ask for 100mm. My machine is a time vampire with so many inexplicable issues, so I'm trying to knock out the issues that *should* have easy explanations. Any help is appreciated!

 

[StevenB]

A dragon standard flow is rated about 15 mm3/s flowrate, which is about 6 mm/s extrusion speed.
A high flow version is about 35m 3/s which is about 14 mm/s.
So a couple questions. What temperature are you extruding at?
What version of the dragon are you running

 

[stevereno30]

I'm using the version that Trianglelab sold two years ago. It has a copper heat block plated in something more durable. My nozzle is a Trianglelab diamond tipped nozzle that is also plated copper and has copycat CHT internal geometry. I've used a dragon HF core before, and it also struggles to push anything close to what it should be able to push. The ABS I am using is rated for temps between 190 and 230 (low, I know... But it looks like butt if printed higher than that). 220 is ideal based on temp tests. The dragon cannot push more than 2mm of filament per second without falling behind, even if printing at 250 °C. There is also significant die swell throughout the temp range. Other ABS filaments with more normal temp ranges also have these issues, so it isn't specific to the filament I am currently using.

 

[vinnycordeiro]

and has copycat CHT internal geometry

There lies your answer: cloned CHT nozzles does NOT perform to the level of the original thing. In fact, you are not the first one saying that the performance is worse.

For science, put a plain nozzle on your hotend and repeat the tests. Also, increase the temperatures: 190C to 230C is the temperature range for PLA, not ABS, no matter what the manufacturer says.

 

[NoGuru]

Also have you tried to extrude with no nozzle just to rule out an issues with the extruder?

 

[stevereno30]

There lies your answer: cloned CHT nozzles does NOT perform to the level of the original thing. In fact, you are not the first one saying that the performance is worse.

For science, put a plain nozzle on your hotend and repeat the tests. Also, increase the temperatures: 190C to 230C is the temperature range for PLA, not ABS, no matter what the manufacturer says.

Here is the test (Ellis' tape method starting at 120mm) repeated with a never used standard brass nozzle. Plastic was extruded at 240°C and 5mm/s linear, 12mm³/s volumetric.

 

[stevereno30]

Also have you tried to extrude with no nozzle just to rule out an issues with the extruder?

Extruding with the hotend hanging off to the side results in exactly 100mm extruded. I tested it with the same extrusion rate, and for lols I tested it at 30mm/s. Both extruded 100mm of filament.

 

[stevereno30]

It may be worth noting that this issue also happens when I fully swap my hotend for a cloned V6. It has been a while since I've tested other extruders, but in addition to the G2 currently mounted, I have a fully assembled G1 and a CW2 I could swap in.

 

[NoGuru]

What PTFE are you using. Is the path easy to push through?
The only other thing I could think of is you have a bent heatbreak but you say it happens with other hotends and extruders.
What current are you running the motor at? Have you tried increasing the current?

 

[stevereno30]

The PTFE in my toolhead is Capricorn brand. My reverse Bowden is 3mm Chinese stuff. I've tried three different heatbreaks (dragon standard, dragon HF and V6 titanium). The motor is running at the stock G2 0.6A. I can try higher current for the purposes of the test, but other G2 users can push plastic at 30mm³/s with their motors set to 0.6A. Mine can't do anything above 10.

 

[stevereno30]

Interestingly enough, it appears to be marginally worse at 0.8A

 

[NoGuru]

Take out that Capricorn, I used to use that stuff but it causes noting but issues as it's too tight.

 

[stevereno30]

Damn... No change. Swapping the PTFE was the first original test I've tried. I was really hoping... Part of me thinks it might be a power issue at this point. I get weird artefacts that cannot be explained with resonance testing, and I get "timer too close" errors from my pi from time to time. The problem is I have no idea how to test for this outside of throwing more money at the printer. Does anyone know any electrical engineers in this community that could tell me what to poke with my multimeter to figure out if my PSU(s) is(are) the problem?

 

[NoGuru]

One other thing I have seen is over torquing the screws to the extruder. Maybe try backing them out a turn to see if its binding inside.
Like disassemble it most of the way and just loosed all of them, but just a little.

 

[stevereno30]

That's an interesting thought, though I'm almost positive that the G2 design is such that there isn't really any way the housing could bind the drive gear unless the screws were so over tightened that the plastic started deforming in a way similar to an elephant foot. Either way, I'll give it a shot.

 

[stevereno30]

Well, nothing seemed to help, so I'm throwing more money at it. I have a Bambu X1C hotend on it's way from China. Though I have strong doubts that my hotends are faulty, I have no clue what else could be causing this.

 

[NoGuru]

Well, nothing seemed to help, so I'm throwing more money at it. I have a Bambu X1C hotend on it's way from China. Though I have strong doubts that my hotends are faulty, I have no clue what else could be causing this.

From China? If you are USA it will come from California.

 

[Dave32]

Is your thermistor type set correctly? And have you run a PID tune?
If the thermistor type is set wrong, then the indicated temperature might not match the actual temperature, and the resulting extrusion (and flow rate) will be impacted.

 

[leograyc]

Here is a thought, have you try different filament type? Like PLA ? We have proved the problem stay with different hotend, G2 is working fine. Given the low temperature of your ABS, it sound strange and that might be the issue.

 

[stevereno30]

Sorry I missed your message Dave. My thermistor is set correctly. I've verified (and tried swapping with a known Generic 3950) with no noticeable changes. My X1C hotend also behaves the same way though it heats up MUCH faster than my Dragon. Temps are PID tuned etc.

For filament types, I could almost definitely print PLA faster, but I don't print PLA. Most of what I print needs to be photostable (PETG) or heat stable (ABS). I know PLA is photostable, but where parts are going to be exposed to sunlight, they tend to get too hot for PLA. Sometimes too hot for PETG as well. Also, the ABS I am printing with now prints well at 260c, and it seems to extrude a little better than the lower temp spool. I am now somewhat convinced that underextrusion is almost guaranteed at Voron speeds. If top surfaces/perimeters are printed slow enough, it doesn't really matter. I want my machine to be perfect, and it seems like it cannot be perfect *and* fast.