Slow Print Speed With 0.2mm Nozzle

Hello!

I have successfully built and started up my first 3D printer (Heacent Prusa Mendel 3DP02) and I have a question about the nozzle size I selected. With a 0.2mm nozzle, what kind of print speeds should I be able to achieve with 1.75mm PLA? The reason I ask, is that I cannot seem to get any faster than 10mm/s without running into problems with not enough extruder flow.

I have tried different multiplier factors on the extrusion (up to 1.2) and tried adjusting the E-Step calibration in the firmware, but it just does not extrude enough to print cleanly.

Should I have gotten a larger nozzle?

Thanks!

That is pretty slow. I will ask a few questions to kick it off.

What temperature?
What layer height?
What extrusion width?
What slicer?
Can you link to a gcode file?
Photo of extruder?
If you watch the extruder carefully when trying to go faster- is the filament slipping or extruder slipping backwards?
What hot end?
Did you set extruder current?
Is extruder motor getting hot?
Is driver very hot?
The reason for the questions is that a larger nozzle may not help if the problem is elsewhere.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Quote
Paul Wanamaker
That is pretty slow. I will ask a few questions to kick it off.

What temperature?
What layer height?
What extrusion width?
What slicer?
Can you link to a gcode file?
Photo of extruder?
If you watch the extruder carefully when trying to go faster- is the filament slipping or extruder slipping backwards?
What hot end?
Did you set extruder current?
Is extruder motor getting hot?
Is driver very hot?
The reason for the questions is that a larger nozzle may not help if the problem is elsewhere.

Thank you for your reply!

What temperature? (215c for PLA)
What layer height? (0.2mm in Slic3r, 0.14mm in Cura)
What extrusion width? (I'm not sure about this one)
What slicer? (Slic3r and Cura)
Can you link to a gcode file? (Attached)
Photo of extruder? (K-Style Attached)
If you watch the extruder carefully when trying to go faster- is the filament slipping or extruder slipping backwards? (Not as far as I can tell)
What hot end? (J-type from China)
Did you set extruder current? (No)
Is extruder motor getting hot? (Not really, a little warm)
Is driver very hot? (No)

I forgot about setting the stepper current. I will check that tonight. Thanks for letting me know it should be able to extrude faster than what I have been getting. As a complete newbie, it is hard to know what is "normal"!

Here are a couple of rules of thumb:

- Maximum layer height is nozzle diameter x 0.8.

SO, for your (tiny) 0.20mm nozzle you would want to set layer height no larger than .16mm.
This is so the extruded filament profile is squished slightly onto the previous layer. That's the maximum layer height, however for better adhesion you may choose to go lower than that.
So one reason you may have had problems is the layer height with Slicer was too high, and that will cause a greater volume to be extruded, this could cause a stall.

- Extrusion width should be between nozzle diameter * 1.05 and 1.70.

So your extrusion width should be between .21 and .34mm. Lower than .21 and you could have adhesion problems (the filament will be stretched), > .34mm and there could be curling.

If you look at the top of the Slicer gcode file it will tell you the extrusion widths it is using. If you use 0 for all the widths then it will do automatic settings for sane extrusion widths as above, but auto settings will vary greatly between different kinds of features - so I recommend NOT using auto, but instead setting a medium value for all widths to start with, say .25 in Slic3r's advanced settings, and set all the speeds the same. Then you will have consistent pressure in the nozzle - easier to calibrate and debug, good layer bonding. You can raise speeds later...

Printing at a slightly higher temperature will make the PLA less viscous, so faster speeds can be achieved.

Please attach a photo of the hot-end on the machine. It has a heat break - do you have a fan wired to blow constantly on that heat break (hardwired)?
The fan should blow there, but not on the metal bottom part of the hot-end. If the heat break is not cooled then that can cause a jam.

Make sure the extruder is clamping the filament very tightly (but not enough to crush it) - so it does not slip.

Another problem can be: the nozzle temp may not be consistent - have you done a PID tuning for the hot end?

Since you have a Chinese clone hot end there could also be manufacturing issues with it (they do not follow the specs), but that's for later...

Hope this helps.

Edited 1 time(s). Last edit at 01/19/2016 01:26PM by Paul Wanamaker.

Wow! Thank you Paul!

It will take me some time to go through everything that you have mentioned, but I appreciate you taking the time to explain it to me. I have learned a lot since Christmas, but having it explained in direct relation to what I have is tremendously helpful.

It is amazing to me how intricate and challenging this is. You have to meld so many disciplines... mechanics, software, materials, and on... what fun!

Anyway, I'll get back to you with my findings!

OK. I have made some progress!

I was checking the extruder feed and noticed that it barely seemed to move when I was printing. This seemed like an e-stop issue so I went back to adjusting my calibration setting in firmware. I increased the value for the extruder from 160 to 240 (50%) and I finally started to notice the extruder motor turning during printing. Now my test prints seem to have too much feed, as I am seeing build up under the print head and getting blobs. I increased my print speed to 20mm/s and it was better, but there was still excess material.

I have also been working with my slicings to get those corrected. I only worked with Cura last night, mainly trying different layer heights between (0.1mm and 0.14mm). It must calculate the extrusion widths internally, because the only setting I see is "Initial layer line width" which I set to 100%. I will experiment with Slic3r tonight and the manually set extrusion widths.

Here is my hotend...





I guess I should think about better cooling. The fan just blows over the entire area...even the heating block.

Ok, I'll tackle the first big issue. Take a look at the following photo (not my printer), at how the fan is blowing on the black peek heat break, but not on the bottom metal part of the hot end.
This is still not ideal, there should be a little shroud directing the air so it doesn't blow on the hot-end at all (that will cool it), and no tape over the black part if possible.
If the black Peek plastic heat break is not cooled then heat creeps up and softens your filament, causing jams.

You need to remove all the tape from around the black peek heat break on yours as a first step. You can duct it later...



Second, you need to calibrate your e-steps per mm. Hit the Wiki button at the top, and then Reference on the left side, and Tutorials. Look for Triffid Hunter's guide. That's a good start to make sure the measured amount of filament being pushed in is correct. I'd do it with the hot end hot (the same environment as when it will be printing).

To fine tune you can use this guide: [github.com]

The calibration pages on the Wiki need to be updated.

OK, I have managed to increase my print speed up to 30mm/s. I was actually able to do 40mm/s but ran into some serious shaking when filling small gaps (I had not discovered the "Gap" speed in Slic3r yet). In part, I think my problem is that my 0.2mm nozzle requires a minimum amount of pressure to extrude... so going slower was only making it worse. It's like there is no middle ground... it's either extruding (a lot) or it's not. Once I calibrated my E-steps and started using some reasonable slicing settings, I finally started to see better results.

BTW: I found this article enlightening...
Extrusion Rate Article

Anyway, I still plan on installing a small 30mm fan to blow on the heat break. It will be a tight fit, but I imagine it can only help.


Thanks again for all your help!

You're welcome. Glad you got it going!

Yes, that's a very good article. I've confirmed that with my own testing.

That is an interesting result - that may be indicating heat creep is the issue - perhaps too slow extrusion and the filament has time to get soft before it hits the hot zone.

Will a fan fit between the rails?

BTW, I've just added a Slic3r Tutorials page to the Wiki that may interest you.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!