Artifacts -

Thoughts about Raise3D, 3D printing and making in general.
MDVolle
Posts: 43
Joined: Fri Oct 20, 2017 9:00 pm
Location: Fullerton CA

Artifacts -

Postby MDVolle » Mon Jun 04, 2018 6:56 am

Looking for a little help identifying/naming exactly what I am seeing in this part - its only purpose was to look at the artifacts -

These are not "problems" in my mind, I'm just curious what they represent - all but the melt at the top - that I understand but didn't do anything to prevent or avoid.

Its a cone that was cut to include a 75 degree section - printed with two shells and no infill - 50mm tall

Drawn in Fusion 360 - output as STL and sliced in Ideamaker

Material is PET+ and layer height is 0.05mm with a 0.35 nozzle. Shells were printed at 35mm/s inner/25mm/s outer.

The one side is completely aligned with the x-axis while the other is at a 15 degree angle to y-axis

I believe that the scar up the curved face is the point that the shell starts/stops - start point was set to "nearest" but I don't understand the texture, as it doesn't match the triangles in the STL - they were much longer/taller. I'll be trying to impact that with the "Make" settings in 360

I have ordered new SD2224 stepper drivers for X/Y and am curious to see how this changes with the new drivers.

Thanks

Mark


Curved face
_DSC0499.JPG

Face angled 15 degrees from Y
_DSC0498.JPG

Face along X
_DSC0497.JPG

Standing as printed
_DSC0495.JPG


75 degree cone.stl
(4.87 KiB) Downloaded 2 times

Jetguy
Posts: 2487
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Artifacts -

Postby Jetguy » Mon Jun 04, 2018 12:27 pm

I'll try to make a more detailed post later today and draw lines and circles on the pictures to identify the errors naming them and showing you where they might be coming from.

Just some basic notes and really a test and work for you.
#1 Print from an SD card directly attached to the mainboard for a proper test and comparison. This is because you likely increased the resolution AKA segmentation at the time of export of the STL before loading into the slicer. We know, it's proven, there is an architectural limit over USB of short segment gcode. You printed a curved object, there is no such thing as curves in STL or gcode, it's a polygon- the finer the polygon the more likely you will choke the USB limit and stall the motion planner in Marlin firmware when printing from the front display over USB. If you want to prove it's not, it requires either you share the gcode and I print it or you print it, but one of us has to print it over SD directly attached with a second control panel to the mainboard. If the same code prints with less artifacts when directly connected- you just proved you hit the limit. Again, pictures and a proven test in this topic. viewtopic.php?f=8&t=6776&p=27238&hilit=stutter#p27238
Either apply the test yourself or share the gcode file you printed- maybe the STL as well for good measure.
$14 on Amazon for a know to work LCD and cable set https://www.amazon.com/KINGPRINT-Graphi ... 076WQQX5K/

#2 Yes, on that print, I see both a Z "zipper" in the face and on the other side, the ringing effect as it rounds the corner. One is gcode, the other requires lowering the firmware Jerk value from the default 12mm/s to 10 or even maybe 8mm/s. Remember jerk is the value of a threshold where NO acceleration or deceleration is applied to the motion. That's why lowering the value stops ringing after a 90 degree corner. Understand what ringing is- deflection and resonance of the head and thus nozzle when it travels and then STOPS suddenly as a 90 degree turn, it stops moving in one direction and bounces back and forth from slamming to a dead stop. This bouncing back and forth decays but it happens as the nozzle begins moving in the opposite direction. This ringing or resonance is a function of the span of the unsupported round rods the XY can is made of. To understand unsupported- by that, I mean again, a round rod only is supported, mounted, held, at the far ends, and the rod spans free open space. When the load is in the middle of this, this is when you experience the greatest deflection and resonance of the system "mass and springing of the rods". Prove it, slice the part by moving it nearer the corner of the built area VS auto placing in the dead center. The Z zipper location is all the slicer settings. It's location and nature is all the slicer and gcode.

#3 PETG is not the best material to print artifact free in. It simply is the flow of the plastic and other details, in my experience it will show every flaw. However, in your case, that may be the intent here, show every single artifact and flaw.

#4. I think I see additional infill ribbing on the outside of the print. This is seen on the same side as the ringing on the corner. One way to be sure is turn off infill for this print (0% infill) and only 2 shells, or better yet, vase mode this print forcing a single shell spiral permitter with no Z zipper. Again- more than betting that would need a direct SD card print to ensure not hitting the USB limits for short segments.


None of this in particular seems to be stepper related. It's all slicer and gcode- along with machine architecture and mechanical derivatives making the artifacts, but we can work through them one by one.

MDVolle
Posts: 43
Joined: Fri Oct 20, 2017 9:00 pm
Location: Fullerton CA

Re: Artifacts -

Postby MDVolle » Mon Jun 04, 2018 10:07 pm

This is very interesting!

I did attach the STL file to the first post and this is hollow - zero infill - 2 shells.
Jerk was at 10 and I am printing one with the jerk at 8 right now - just to see how it changes.

The bottle neck is intriguing - makes perfect sense to me but seems like a real "fly in the ointment" kind of problem.

Does this also respond to print speed? it seems that if you slow down the print speed, the time to receive the next piece of code would go up - unloading the log jam in the USB path? Or are the segments so short that the actual print time is trivial compared to the message latency?

It seems like the "correct" (if there is such a thing) answer would be to have a buffer on the board although the idea of concatenating the code lines to reduce overhead would also seem to provide relief if it could be done in the panel processor.

This may explain issues I have had earlier with some extremely smooth but complex curved surfaces.

Essentially, the shape starts as an airfoil profile but it scales smaller as it goes while also raking backwards and up - I am sure that it contained MANY short segments and the surface was never smooth - so I abandoned the project until I found a better way to produce the wingtip.


I think my hobby budget for the month is "spent" (even to the point of a $15 controller) at the moment but I will attach the g-code file that IdeaMaker generated for this as well.

I had to change the .gcode extension to .txt to post it.

75 degree cone .txt
RENAME to .gcode -
(1.44 MiB) Downloaded 4 times

Jetguy
Posts: 2487
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Artifacts -

Postby Jetguy » Tue Jun 05, 2018 12:36 pm

I have to say, this gcode seems to be more troubling that I first guessed. I attempted multiple test prints last night using your exact gcode on both an N2 Plus and an N1 (after carefully checking to see the gcode would "fit" the smaller N1 build area.
None of the prints came out great. On the N1, I printed in Raise3D PLA and adjusted the temps, but otherwise ran your verbatim posted gcode. On the N2 Plus, the first print was with some older MadeSolid PET+, because the only other PETG I had around was clear and would not be good for trying to see and diagnose print quality. Twice on the N2 Plus I tried printing the same file from SD card via an attached GLCD to the mainboard, and both failed after the first few layers and stopped extruding. I mean literally, it was as if the extruder motor was no longer being commanded to feed filament.

That said, based on the PLA print on the N1, I think you might be experiencing the ripple on the front face from the stock feeder and A4988 stepper driver interaction. I'm trying to find a post by another N1 user I helped with the same issue who fought that artifact and then changed to a Bondtech and it went away. That just a feeder, not a hotend change so that literally means the filament and thus extrusion whas varying just slightly and may line up with the gear teeth or motor full steps. The reason a Bondtech would change that is the change in steps per mm to a higher value (415 for the current series of upgrades VS the stock 95). Yes, it can make a difference.

I'm not saying that all the problems with this print, but for me, there are some issues with the gcode and this print should turn out better than this.

MDVolle
Posts: 43
Joined: Fri Oct 20, 2017 9:00 pm
Location: Fullerton CA

Re: Artifacts -

Postby MDVolle » Wed Jun 06, 2018 5:41 am

JetGuy-

I have finished two more cones with slight differences -

These are ALL with the Bondtech dual direct, factory heatsink, custom copper block and a 0.34 nozzle (nominal actual extrusion about 0.331-0.337)

First layer is 0.20 and rest are 0.05mm - Two shells with zero infill and same temps for all

Same object sliced in the same settings except for one setting - I increased the minimum time/layer for cones 2 and 3 but didn't actually change the minimum speed allowed - so very minimal change and only effects the very top of the cone.

Cone 1 on left was with the jerk set to 10
Cone 2 in center was with jerk set to 8
Cone 3 on right was with jerk set to 8 BUT with new SD2224 drivers on X/Y

Photo of 15 degree off of Y-Axis side:

_DSC0503.JPG


Photo of curved face:

_DSC0502.JPG


Photo of X-axis side:

_DSC0501.JPG


I find the PET+ to be truly annoying to get to start - extremely small changes to table height go from not sticking to making strings all over - I have to adjust about 0.003 at a time and have a micrometer for the table "stop" that hits the switch.

If it starts right, PET+ seems like a great material for usability but melts on the nozzle, starts hard and shows everything - much prefer Nylon but that you have to keep drying out the stock...

MDVolle
Posts: 43
Joined: Fri Oct 20, 2017 9:00 pm
Location: Fullerton CA

Re: Artifacts -

Postby MDVolle » Wed Jun 06, 2018 5:45 am

This is another PET+ part with thicker layers and a random start point -

Its yet another stupid test object I use but this is printed in vase mode - Jerk 10

Factory Extruder
Factory stepper drivers
Copper heat block

On this, I don't think I see any sign of a z-axis artifact?

_DSC0504.JPG
_DSC0505.JPG
_DSC0506.JPG
_DSC0507.JPG
_DSC0508.JPG


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