hole in prints, problem ?

[ubi90 0]

Hi,

Got a problem on UM2 with bad prints (holes) as you can see on this pic :

https://www.dropbox.com/s/21cw7h9iqa11dah/20140512_121226.jpg

It seems that there are some very little holes happening during the print. it is not filled 100%.

PLA 210 / 75

Filament 3mm

Fan speed 100%

Layer 0.1mm

Thx for help !

 

[IRobertI 520]

That's underextrusion.

Is your filament actually 3mm or is it closer to 2.85mm? If it's actually 3mm that could be the problem as slight variations in the filament diameter might make it too thick to pass through the machine cleanly.

I don't know what speed you're printing at but 210C might be a bit low on the temperature side.

I would also drop the bed temperature to 60-65C instead. It improves overhangs on the lower sections of parts and it takes less time to reach temp if you're impatient

 

[ubi90 0]

thx for those advices. I will finish my print with 230°C.

The diameter is 2.94 2.92

Speed is 100mm/s

Speed is ok i guess.

 

[skint 61]

3mm is closer to causing friction in the Bowden tube, however should be fine. It`s much worse when there are bends or small defects in the material though. From the colorfabb I have measured they rarely go over 3mm.

Faberdashery filament that I use is pretty accurate, a constant 2.85.

Ubi, like Robert said drop your bed temp to more like 60c, you can see your parts have started to lift in the corners.

 

[IRobertI 520]

I think you will have better luck at 230C at those speeds. If you want to improve the surface quality I would cut the speed in half. Slower is almost always better if you're going for pure quality.

And to answer Osgar and also add to the original question. It's always recommended to put in the actual diameter of the filament for best results. Say your filament is 2.95mm in diameter but you have set it to 2.85mm (the default) in cura or on the machine, then you will actually be overextruding filament. The firmware expects that X steps of the stepper motor will extrude Y amount of plastic but since the filament is larger than what it expects you will actually get more plastic than intended.

 

[dtreacy 0]

This is the post I've been looking for.

Currently having the same issues and banging my head against the wall.

I have a large print which takes approx 17 hours and I'm on the 3rd attempt but am learning with each trial.

What I've learnt so far.

1st Print failed due large holes in the print. I believed that these were caused by too thin a surface thickness (6 layers) and low % infill (15%) was causing holes.

2nd print (currently running)

Based on some research I decided to increase the surface thickness to a magic 10 layers and the infill from 15 to 30%, however this was pushing my build times out, so being impatient I also increased the speed from 50 to 125 mm/sec.

Unfortunately this this has caused another surface problem as the horizontal surfaces are full of small holes which looks abit like "stuck together sugar crystals" ( a nice effect on the print) but this is still a failure.

As the print is currently running I've increased the nozzle temperature as per the advice above from 210 to 220 and this seems to have had a noticable improvement in the surface finishes (currently no holes)

The 3rd print (which will go on tomorrow) will hopefully be a success due to a good infill (30%), 10 layer surface thickness (1mm) at 0.1mm layer thickness and a nozzle temperature of 220degC or higher to compensate for the faster print speed of 125 mm/s.

Fingers crossed.