MakerFarm Pegasus 8' Printer Problem

Hi, I use MakerFarm Pegasus 8' printer: http://www.makerfarm.com/index.php/pegasus-8-kit.html

I have been getting some melting or filament (1.75 mm PLA RoHS) issues with my 3D printed parts. The spaces are coming together. I changed the temperature of the extruder and changed a couple of different parameters but they did not solve my problem. I attached the pictures of the parts. Hope somebody can help.

Thanks.

Layer Height: 0.25
Perimeters: 2
Shells: 3, 3 (bottom and top)
40% Infill
0.4 mm nozzle diameter
180C Extruder Temperature
60C Bed Temperature


Attachment 9179Attachment 9180

I am having a hard time understanding your problem. Can you rephrase what the issue is and what brand of filament are you using?

Well, I think the pictures are pretty self-explanatory. I do not know what to say more. That front part in the second picture and side in the first supposed to be rectangular side by side, by as you can see some of them are almost sticking together. Some people say that it is due to retraction parameters but changing them did not solve my problem.

Has the printer extrusion been calibrated?

In what order do the uprights get printed? Am I correct to guess that the layers are printed on the left upright first, and on to the ones on the right? I'm thinking this is still retraction related - perhaps that no retraction is occurring. This would be evidenced by the first upright coming out fairly well, with more and more excess filament being present as the printer moves to the uprights on the right. I'd elaborate on what retraction settings you've tried. Do you actually see the large gear reversing between each upright? It could be something like the extruder motor being driven too fast on retractions - a flaw in at least older configuration files MakerFarm provided.

EDIT: The extruder motor speed is the fourth value in DEFAULT_MAX_FEEDRATE, found in the configuration.h file. In at least older versions of Marlin, this was also Vmax E on the LCD display, or accessible via an M203 gcode command. MakerFarm used to set the extruder max feedrate to 22 mm/sec, a value some of us found to be hard for the printer to reach. I found 15 mm/sec was acceptable, but a value of 10 mm/sec has been recommended by some. If the motor can't hit the commanded speed, it just twitches and you get no retraction.

If this were a smaller object, I'd suggest applying some cooling airflow to ensure the layers are solid before being printed on - this can often be a problem with small uprights like posts. But on a large object like this appears to be, layers should be cooling off pretty well in between layers. Printing PLA on a hot bed while also using painters tape is unusual. Maybe the heat from the bed is keeping the print soft. Watch the print - if you see the uprights shifting AT ALL while a new layer is being printed, you'll never get a good result. If that's happening, try printing without heating the bed. Swabbing the painters tape with alcohol should give you plenty of adhesion. Or, go ahead and test a bit of airflow from a small table fan or something to see if that makes a difference.

Thanks for your reply.

Well, I built the printer in a workshop so before doing anything, we checked everything but after that have not done any calibration. I am new to 3D printing so do not know how to calibrate.

Yes, it prints as you described. I also attached new pictures and apparently, the problem is only the front part (towards to front). It seems that when it finishes a layer and comes back to start a new layer, it kind of pushes a little more filament. Yes, this might be still an issue about retraction.

I have not had any issues with the printer bed but I will keep an eye on it.

Retraction:
Length: 2.5mm
Lift Z: 0
Speed: 40 mm/s
Extra Length on restart: 0
Min. travel after retraction: 3 mm
Retract on later change: checked
Wipe while retracriong: unchecked

Attachment 9190Attachment 9192

There's a sticky in this subforum that provides some help with calibration. Or, google 'marlin extruder calibration' for any of a number of calibration resources. The calibration guide by Triffid Hunter gets a lot of recommendations throughout the reprap community. The key thing to focus on here is ensuring that your extruder is providing the volume of melted filament volume that the slicer is assuming. You also have to measure your filament diameter and set that in your slicer since raw filament is rarely the exact correct diameter. You really should do this before trying to work through any print quality issues. If nothing else, the calibration process removes a few of the many variables involved in getting a good print.

I just realized the Pegasus doesn't have a Greg's Wade extruder, so my earlier question on whether the large gear is ever reversing won't make sense to you. I guess what you could do is lightly pinch the filament above the extruder and feel whether the filament is ever being pushed upwards. Your settings should cause the filament to move backwards 2.5mm for each retraction.

One thing you could look at is the distance between the columns in the print. Note you're telling the slicer (you might clarify what you are using for a slicer, including the version) to NOT do a retraction for move distances less than 3mm. Any chance the distance between columns is less than that? You can also look at the gcode file in a viewer like gcode.ws to see what the slicer is telling the printer to do, including where it is supposed to be doing retractions.

I'm leaving further support to the thread to others with Pegasus experience - I don't know how sensitive the Pegasus is to retraction extruder motor speed, etc. Good luck.

Quote:

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Originally Posted by printbus

There's a sticky in this subforum that provides some help with calibration. Or, google 'marlin extruder calibration' for any of a number of calibration resources. The calibration guide by Triffid Hunter gets a lot of recommendations throughout the reprap community. The key thing to focus on here is ensuring that your extruder is providing the volume of melted filament volume that the slicer is assuming. You also have to measure your filament diameter and set that in your slicer since raw filament is rarely the exact correct diameter. You really should do this before trying to work through any print quality issues. If nothing else, the calibration process removes a few of the many variables involved in getting a good print.

I just realized the Pegasus doesn't have a Greg's Wade extruder, so my earlier question on whether the large gear is ever reversing won't make sense to you. I guess what you could do is lightly pinch the filament above the extruder and feel whether the filament is ever being pushed upwards. Your settings should cause the filament to move backwards 2.5mm for each retraction.

One thing you could look at is the distance between the columns in the print. Note you're telling the slicer (you might clarify what you are using for a slicer, including the version) to NOT do a retraction for move distances less than 3mm. Any chance the distance between columns is less than that? You can also look at the gcode file in a viewer like gcode.ws to see what the slicer is telling the printer to do, including where it is supposed to be doing retractions.

I'm leaving further support to the thread to others with Pegasus experience - I don't know how sensitive the Pegasus is to retraction extruder motor speed, etc. Good luck.

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I have not printed with my Pegasus yet but the last direct drive extruder I had required very little retraction like 0.3-0.4mm where as my Prusa requires 1.2mm.

Quote:

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Originally Posted by printbus

I just realized the Pegasus doesn't have a Greg's Wade extruder, so my earlier question on whether the large gear is ever reversing won't make sense to you. I guess what you could do is lightly pinch the filament above the extruder and feel whether the filament is ever being pushed upwards. .

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There is a bearing on the front of the extruder (mounted opposite the hobbed gear) that you can watch and see very easily what the extruder motor is doing.

Quote:

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Originally Posted by printbus

I'm leaving further support to the thread to others with Pegasus experience - I don't know how sensitive the Pegasus is to retraction extruder motor speed, etc. Good luck.

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Sorry, can't help there as I have not touched those settings on mine and know nothing about them.

I actually followed a few steps and checked my printer's calibration. It was really good. It almost takes the same amount of filament that I wanted to extrude (set to 100 mm and measured 100.21 after extrusion). Followed the instruction here:https://www.youtube.com/watch?v=YUPfBJz3I6Y

Quote:

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Originally Posted by flatty_420

There is a bearing on the front of the extruder (mounted opposite the hobbed gear) that you can watch and see very easily what the extruder motor is doing.

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I did check if the extruder does retraction and it does. I can even see the what the motor is doing as flatty_420 described.

I have been watching as it prints and as I said before, when it starts a new layer -at the very beginning of the new layer- the extruder extrudes just a little bit of more filament than it usually does and I guess that is why it causes this problem. (I also measured my filament and it was always around 1.75-1.74-1.76 so averaging it changed nothing).