Consistent Gaps Between the lines of Infill.

[Abhishek_94 0]

Hi!

I am using Ultimaker 2 and facing a issue in Print Quality i.e. Consistent Gaps Between the Lines of Solid Infill of Top and Bottom Layer. I checked the software settings also, nothing strange with it. I checked the hardware too, its fine also. Actually, the material flow is consistent throughout the print. I am attaching the snapshot of the settings I'm using in Cura.

I am Using Cura 15.04.4 for slicing up the model and generating the gcode file.

I am attaching the image of the print as well.

I also changed the material flow to 130% but it seemed no help to me. However the dimensions of the print is coming out to be accurate.

What would be the problem? Please help!

Abhishek

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[DidierKlein 729]

Hi and welcome to the community!

First of all i find your speeds quite high just needed to mention that.

At 0.2 layers and 80mm/s with a 0.8 nozzle your are extruding at: 0.2 x 0.8 x 80= 12.8mm3/s which is a lot. Maybe reduce the speed to 40mm/s.

Anyway, the picture shows the top part of the print?

It could be either:

in expert settings; Solid fill top is unchecked so what you see is the 50% infill.

No enough top/bottom layers

Or underextrusion because of speed to high

[Abhishek_94 0]

@DidierKlien Solid fill top and Solid infill bottom is checked. I think that the material flow is stabilized but it is skipping some lines of extrusion consistently.

Can you help me with the procedure how to detect the under extrusion?

Thanks!

Abhishek

[DidierKlein 729]

but it is skipping some lines of extrusion consistently.

This is what under-extrusion means.

Really try with a lower speed it will most probably help a lot!

[Abhishek_94 0]

@DidierKlien I printed a simple box at printing speed of 40mm/s(almost half of the last time's speed) made all the speed to 0.0 i.e. 40mm/s.

It looks like problem still persists. Please Review the Image and Suggest me some solution for it. There's still gaps between the extrusion lines.

[gr5 1,998]

What temperature are you printing at?

I would put flow back to 100%.

You need to see how fast you can print before you get these gaps so reslice the cube to be solid and maybe set shell to 0% also (infill 100%). Set your infill speed to 100mm/sec so you can adjust the percentage and the percentage will equal the speed - so for example 20% will be 20mm/sec.

Then ignore the first layer of the print. Once it starts the second layer slow it to 20%. The lines should be touching. Then speed it up slowly until you start getting gaps. Make a note of the speed. Then raise the temperature in the tune menu by 10C and repeat the experiment. Repeat this a few times until you are up to 240C maximum (for PLA). Post your results please.

You will learn a lot in just 10 minutes because you can do this while it's printing from the tune menu. You shouldn't even have to finish the print.

[gr5 1,998]

By the way you have a second problem which you will probably think is your main problem.  It's not!  Your main problem is underextrusion.  The second issue is you have some play (aka backlash).  That is what is causing the two lines and then gap - two lines touching - then gap.

I don't know what is causing the backlash - make sure the long belts and also the short belts are tight - possibly the X or Y stepper slid up a mm within it's slot - loosen the 4 screws and push down hard and retighten the 4 screws on the stepper. Repeat for both steppers.

Alternatively you may have very high friction.  Push the head around with power off - look at the two 6mm rods that pass through the head - do they look perpendicular or crooked?  It's common that one of the belts slips a single gear tooth.  To fix - loosen the pulleys at both ends - make the 6mm rods perpendicular and retighten.  Tighten the hell out of those pulleys - enough to bend the hex tool.  it's easy to make them perpendicular if you push the head all the way to each end until the blocks can't go any farther.  it doesn't have to be perfect - just good enough that you don't have very high friction.

Edited March 2, 2016 by Guest

[Abhishek_94 0]

@gr5 thanks for the suggestion..I followed your first remedy .

I found that there are no gaps when the print is going on 20% , 30% and 35% repectively. However At speeds higher than the 35% the gaps started to form. Also I did a iteration by increasing the temperature to 10C but it didn't help.

Then I checked the Head along those rails. The rails are perfectly Perpendicular. The greasing on the rails are enough to provide the lubrication i.e No Excessive friction.

Now I am going to check back the pulleys and there relative motion with the motor shaft.

I will then revert you with the results. (hopefully good results)

[neotko 1,417]

Maybe you just one of that phantom 10% achines.

I would run a estep calibration at the temp speed you need to use and meassure the amount of filament moved. But for that you need pronterface/printrun and command the printer by usb to move the filament at the same speed as you print the top layers.

Slower speeds fills the gaps because the flat nozzle area has more time to flatten and blur the machine/preassure errors.

Ofc first check with other filament, check that you can manually push the filament (out of the feeder or with IRobertI feeder, or releasing the filament on +). And check how it fells to push it. At 230 it shouldn't need a "strong" force (hard to transmit how much by text.

Other option it's just to do it brute force and print different boxes adjusting the flow % (works less precise than esteps but works) until you get a perfect flat surface at the desired temp/speed.

More info about what I mean by nozzle faking and blurring:

http://www.3dprintingforum.us/viewtopic.php?f=9&t=4&start=15#p667

And my digging on the 10% extra that ultimaker uses on his esteps to compensate for bowden/filament/distance preassure:

https://ultimaker.com/en/community/19330-esteps-and-ultimaker-o-and-the-magic-missing-10

[gr5 1,998]

Great - now you know - 35% speed should be your max speed.  Trust me if you go up to 240C you can go faster than 35%.  I wish you tried lower temperatures down to 190C.  You will see the quality gets noticeably better at 200C but of course you have to go slower also.

So what was your printer speed and then what is that speed multiplied by 35%?  And what was your layer height?  I want to confirm that your printer is not defective.

[Abhishek_94 0]

I tightened the Motor Mounting Screws, Motor Pulleys of both X axis and Y axis.

I actually observed some knocking sound in feeder mechanism very frequently. Due to which everytime the knocking sound comes, the feeding stops for a second or half and hence creating gaps between the gaps.

Any Suggestions?

Abhishek

[gr5 1,998]

>suggestions?

Yes. Don't ignore the questions people ask of you. Please answer those questions as soon as possible.

The knocking sound is common - that's what happens when the force is too high for the feeder motor and it skips backwards and you get zero extrusion for about a second until it catches back up.

The pressure that the feeder motor can put out is impressive - about 5kg. So you have very high forces keeping you from printing. Answer my earlier questions and I'll let you know how to deal with the knocking and your underextrusion.

[Abhishek_94 0]

@gr5 My sincere apologies for that!

I set the infill speed to 100 mm/s as told by you and reduced the shell thickness to zero so there would be only the infill that printer will print.

35% of that speed will be 35mm/s. The layer Height was 0.2 mm.

I am attaching some images also for what happens to the walls of the model at 0.2mm layer height using 0.8mm nozzle. (if I provide some finite shell thickness).

Abhishek

[gr5 1,998]

So 35mm/sec at .2mm layer and .4mm nozzle is 35*.2*.4 = 2.8mm^3/sec. If that's the top speed at 220C then I think your printer is a bit sick. But your first post was more than 4X faster than that. So these are kind of 2 extremes.

Or was the test with a .8mm nozzle? If so that changes everything! I guess I'm getting very confused with partial information. What was that heart printed at - I need to know:

temperature, volumetric speed, nozzle size. Those are the 3 key variables. Volumetric speed can be calculated knowing layer height, print speed and nozzle width (just multiply the 3 numbers together).

Is your printer new? How many hours printing? If your printer is indeed defective (I'm not 100% convinced yet) then consider putting the filament on the floor and consider trying a new teflon coupler. Those are the top things to reduce underextrusion (other than printing slower/hotter):