A lot of bumps/pits on my prints.

[bassamanator 1]

I printed a little box that didn't come out as nice as I had hoped for:

So I thought that maybe this was all related to the TMC2209 stepper motor drivers I had installed so I decided to switch them back. But before that I printed the cylinder on the right (2209) and after switching to the stock drivers I printed the cylinder (same gcode file was used) on the left. All the bumps/pits are identical on both prints so much so that if this was a court case, there would be a conviction:

It's hard to see in the picture but I'm not exaggerating in how identical the bumps/pits are on these 2 prints.

 

https://imgur.com/a/UndkR46

 

I've done the following:

-temperature tower: 215C. I'm confident in this value.

-retraction tower: 5mm. I'm confident in this value.

-I also calibrated the extruder. It does extrude the correct amount.

 

I'm going to try the following:

-revert back to official firmware

-switch out the nozzle as soon as my wrench set gets here.

 

What more can I do to clear up these prints?

 

Thanks!

 

davidramiro v1.4.6 firmware (Marlin 1.1.9)

Anycubic Mega S

Sliced on Cura 4.8.0 on Manjaro

Ubuntu connected to printer

Octoprint

[Torgeir 264]

Hi @bassamanator,

 

Well, this also looks like it could be an issue with your filament.

If the filament has attracted water, it can look pretty much like this.

 

Thanks

Torgeir

[wjbdesign 1]

Hi @bassamanator. 

First a small disclaimer: This is my first post and I'm fairly new to 3d printing and especially using an ultimaker.

I had the same problem with a cylindrical object and cura 4.8 a few days ago. There are a lot of settings in cura that can help with this problem. For instance: adjusting the Outer wall wipe distance, turn of wall overlap compensation  changing the max comb distance without retraction or experiment with Z hop settings.  

However, I just kept on having problems until I lowered the STL refinement in my CAD software (fusion 360). I do not now exactly why, but it did the trick for me. Al objects printed perfectly afterwards (with no loss of detail)

I hope this will help you, 

regards, 

[gr5 2,230]

commenting on wjbdesign post above:

People think cranking up the resolution in CAD will make a print better but if there are too many triangles in the STL that means there are even more moves in the gcode and the firmware in printers can only look forward about 16 moves and has to be ready to stop and can get overwhelmed if there are too many moves in the next 8mm of printing at any given moment and this can cause the printer to stutter (slowing down and speeding up too much) and this can cause ugly prints.  Only one possible cause among many.

 

So yes don't have too many triangles in your STL.  I've seen prints with 10 triangles in 1mm of travel on corners.  That's too much.

[GregValiant 1,351]

When I first moved to Cura 4.7 I noticed a fall in print quality. Curves and arcs were very blobby, and I didn't know what had happened.

About the time that 4.8 came out I read a blurb someplace that explained that the Creality printers weren't capable of handling the fine resolution settings contained within the Cura machine definitions for the Creality printers.  The main problem was with the Mesh Fixes | Maximum Resolution of 0.05.  An adjustment to 0.4 made a huge difference in the quality around curves and arcs.  The number of extremely short line segments was reduced and my printer/planner was able to keep up with the information flow and the stuttering went away.  This is the same type of thing that gr5 is talking about.  All the printers are at least slightly different and in my case the settings were causing way more calculations than the printer was capable of handling in the time allotted for the moves and so it would stop and wait for the calculations to complete.  Every stop left a blob.  

That was about curves and arcs and may be an issue with your cylindrical models.  Another thing is the Zseam on cylinders.  I leave it in a line.  If I need to remove it it's easier to do with a file or sandpaper if all the blobs are in a row.

 

There are different problems that occur in straight lines because resolution likely doesn't come into play.

There have been many posts on Reddit where I see that a machine was put together by the proud new owner and not enough attention was paid to those parts that came pre-assembled.  The number 1 problem are machines that haven't been squared up.  The number 2 problem is not checking that the wheels and belts are adjusted correctly.  Any wobble in the print head (X) or in the table (Y) results in position inconsistencies and the nozzle doesn't follow the exact same path from layer to layer.   The result is that the layers aren't quite on top of one another and you can see that in the finish of your walls on that print.  The problem with loose belts is similar in that the stop positions can vary and when the print head takes off in the new direction it isn't quite at the correct point in space.  It's inconsistent.

 

I only bring this up just in case @Torgeir, @wjbdesign, and @gr5 didn't give you enough to think about today.  Good Luck, and remember "Everything affects Everything".

Edited April 5, 2021 by GregValiant

[bassamanator 1]

@Torgeir @wjbdesign @gr5 @GregValiant

 

All of you have given me much to think about. Thanks!

 

I have done a few more things:

-flow rate has been adjusted to 95%. I am confident in this value.

-the gantry (I think that's what it's called; the thing that moves the nozzle up/down on the Z-axis) was slightly lopsided. It is now square. I will check it again after printing.

-the print head does not wobble.

 

I need to check a few more things that were mentioned. Will report back. Adjusting the flow rate has had a significant positive effect btw. To be fair to the printer, I'm not unhappy with most of the prints, I just think there's room for improvement.

 

Appreciate all the wisdom guys/gals.