New to 3D with Centauri Carbon - pressure advance?

[Dean_Rantala]

Good evening.

So just unboxed my CC and did my literal first print: riser w/ vents upgrade.

Used PETG (I already had a case of the stuff). Generic (no name) filament.

Used the built-in Elegoo slicer settings. Figured out enough to get it to print.

17 hours later… print came out okay. Looks rather decent - but absolutely not functional. After nearly 1 hour of trying to clean the supports off and free up the slider (well aware of the punchout hole in the side to help break it loose).. I literally shattered one trying to get it to slide.

I noticed that while printing, after the first 3 or 4 layers that there were these little boogers / nibs building up on a few spots.

This was a brand new roll freshly taken out of the dry vacuum sealed bag - so huidity is likely not too much of an issue.

Compating photos of my result -vs- what I found online leads me to beleive that I may need to do one (or both?) of two things:

1. Increase layer height by .02mm or so or…

2. Do a pressure advance calibration.

I figured I would start with #2. This is built into Elegoo (Orca) slicer. So I went to “Calibration” and then clicked the pattern. Sigh… the stupid slicer sprawls the patterns across 2 plates! Nothing seems to work like in the demo videos online.

Now I can not even click the dots (pre-slice) to drag them around to plate one (nothing is even clickable). I was trying to move all the patterns to 1 plate so it would all print in 1 round. I assume the second plate pauses and would prompt me to empty the 1st so the 2nd can continue? Hell - literally no documentation comes with a 3D printer to explain stuff like this that is likely obvious to 3D printing veterans.

2 days of messing with this thing and I feel utterly defeated. How the hell do I do the “12 pressure advance samples on one plate” like the online videos show? What am I missing? Is my Elegoo branded Orca slicer just screwed up? I entered “DD”, “Pattern”, “1000,2000,4000” and “50,100,150,200” as shown in the video and get 12 dots spread across 2 plates.

I know everyone says “start with PLA bla blah blah..”. I have absolutely no use for PLA - the only reason I purchased a 3D printer is to make functional parts that need to hold up. I will never make a trincket, toy, helmet, etc. PETG seems like the minimum I need to learn.

Already starting to regret not spending the extra $600 for a Bambu X1C lol..

Looked around YouTube and found very little specific to the Elegoo version of Orca slicer. I keep circling around to the same issue: things look similar but never the same as in videos.

Just trying to start with the pressure advance calibration. Should I do a tower instead? Or maybe a line? Again.. I am utterly overwhealmed with everything I am trying to come to grips with here. I write software for supercomputers 8 hours a day and this 3D printing has made me feel like a complete idiot.

Any pointers would really help

[WillAdams (William Adams)]

The physical stuff is different.

I would recommend picking one of the basic calibration guides and just working through it in order — I found one, which I was going to try, but first I need to try the Elegoo PETG-GF settings in the update I just downloaded (maybe it was there before and I missed it?).

That said, I’ve just been using the defaults (but I mostly buy Elegoo-brand filament) and it’s been working well in my CC.

[Dean_Rantala]

So I played around a bit last night with some small prints.

I watched the guides for all 3 versions of the pressure advance calibration. Regarding my “issue” of all 12 patterns not getting laid out on a single plate - seems the people in the example videos are using printers with larger build volumns?

Anyway, I realized that while the pressure advance IS something I should calibrate very soon - it was likely not the cause of the periodic “smearing” or “globular nibs” that would get boogered across a print. So I did the following based on photos and other recommendations found across the internet:

1. I increased the layer height from .2 → .24 for both first and normal layers.

2. I decreased the flow ratio from 1 → .92

From my reading around, it seems that the problem has not been inconsistent flow. It has been slightly too much. My last couple small prints came out pretty damn smooth and flawless. No periodic smearing or boogers.

I am going through some more videos now about fine-tuning flow rates, etc.

Part of all this is twofold: 1)I just had to start with a dificult-to-begin-with filament and 2) I am using some random no-name PETG filament that came from Aliexpress.

But so far, so good.

[dougl]

You will find you do not want to deal with any filament vendor which can’t produce consistent results. There is enough going on in the hotend, extruder and motion to deal with to then also have to deal with variations within the filament beyond temperature and possibly speed.

My CC out of the box, after the first running the builtin calibration routines it was tasked as job #1 to print the pre-installed Benchy and it came out perfectly. I used PLA which was freshly pulled from 5 hours in the drying box.
Next, I installed OrcaSlicer and set it up for the Elegoo CC and sliced the CC Mini Poop holder model with the Filament setting: Generic PLA and the Print setting: 0.20 Standard Elegoo CC 0.4 nozzle. It too came out perfectly.

I hope the you had run the initial machine calibration routines which are built into the machine firmware. And I know my filament is usable( HatchBox brand ) because I’ve used it in other machines so no unknown there. The fewer unknowns the better when doing anything for the first time.

[mcdanlj (Michael K Johnson)]

I’ve been satisfied with Duramic PETG in the past. (I’m using ABS now and mostly get Gizmodorks ABS.)

[Dean_Rantala]

So I have run a few more small prints.

I have both first layer and normal layer height at .24

Overall.. it seems to be printing better. The first layer is still a bit hairy here and there.. but overall the globbing afterwards seems to be gone.

I also slowed the speeds waaaay down:

1. First layer = 50

2. First layer infill = 80

3. Outer wall = 120

4. Inner wall = 160

The above seems to resolve some of the smearing around the corners for now.

I have certainly done all the initial calibration routines that come with the printer. 45 minutes or so. What I have NOT done yet is the pressure advance calibration - which I think will resolve some of the pending 1st layer issues. When drawing circles on the first layer, I notice where the seam is - that is where some of the globbing wants to start still. But this is only on the first layer - after the first layer, it seems to be running pretty clean.

I am going to do myself a favor after xmas and buy a few rolls of premium PLA+ and maybe even some of the Elegoo-branded PETG. I need all the help I can get lol..

I live in central mexico and we do not have the same veriety of filaments here that exist back state-side.

Man… this stuff (PETG) is just stringy as hell, too.

Honestly, most the stuff I will be printing is going to be guides, small brackets, structural parts for electronic circuits, etc. Maybe an occasional small enclosure for amplifier boards, crossover circuits, arduino project, etc.

Running a 2.5 hour print now - desiccant holder. Gonna see how it goes.

[mcdanlj (Michael K Johnson)]

Yes, PETG is stringy. You can experiment with temperatures. You might find that you need higher temperatures especially when printing faster. And PETG definitely behaves better when it’s dry. It adsorbs water aggressively. I hated printing with it until I bought (and then later built my own) dryer. That made a huge difference in printing experience. And I’ve removed substantial amounts of water (4–5g) from newly-opened filament. Sometimes you get lucky, sometimes you don’t.

[dougl]

besides pressure advance, retraction settings are what’ll effect blobbs at seams. Here’s my settings which IIRC are mostly defaults:

[Dean_Rantala]

Same as mine.

I have tweaked things to the point that I am now getting very reliable and good-looking prints except for the first layer. First layer still looks smeared with hairy-ish blobs here-and-there. The first layer IS completely covering the bed, however.

I asked over on Redit (where I can post pictures) about the first layer issue and someone commented that I may need to increase the height. They mentioned that due to how transparent the first layer looks, I may be starting too thin.

To which I replied:

“Should I then increase the first layer height from .24 to .26? Or should I increase the z-offset? If I do the later, should that be done at the printer or the slicer?

I just read up on retraction setting… my prints are currently featuring a .5mm z-seam where applicable. Would this also cut back on this a bit? How much should I add? Increments on .02 or .05? Or a while .1 at a time?

[Dean_Rantala]

Maybe I can upload pictures….

First layer:

3 layers in:

See that little glob on the brim around the 8 oclock position?

Finished product looks pretty good otherwise:

[dougl]

I recently installed OpenCentauri and after doing the initial recalibration/leveling my first layer was too thin so I just adjusted the Z offset in the slicer.

[Dean_Rantala]

Excellent, thanks for the advise. Seems someone over on reddit thinks the same.

I did some in-depth reading to understand the difference between first-layer height -vs- z-offset since they seemed like the same thing…

But lo and behold: nope. If I adjust the first layer height to be MORE, then more filament will be extruded (extrusion ratio is a direct function/product of layer height and travel speed).

But increasing/decreasing z-offset changes this same height without touching the extrusion rate.

My only question now is this - and it may be dumb..

Under the slicer z-offset, in order to add space - would I enter .02/.04 or -.02/-.04? Which way moves the bed down? My initial assumption is: z-offset is “distance from nozzle” and hence any positive number moves the bed further away (downward) for more first layer height.

Gonna try this when I get home this evening.

[dougl]

@Dean_Rantala

My only question now is this - and it may be dumb..

Under the slicer z-offset, in order to add space - would I enter .02/.04 or -.02/-.04? Which way moves the bed down? My initial assumption is: z-offset is “distance from nozzle” and hence any positive number moves the bed further away (downward) for more first layer height.

Not dumb at all. you move Z offset a positive number to increase the z height(ie bed goes down and effectively the hotend goes up).

It’s good to see someone working out what’s going on instead of just asking for someone to tell them an answer. We like seeing people learning and understanding besides just fixing a problem.

[Dean_Rantala]

It’s good to see someone working out what’s going on instead of just asking for someone to tell them an answer. We like seeing people learning and understanding besides just fixing a problem

This is the default mindset for us who started with Atari 800’s and built our first 386 DOS computers on the bedroom floor

That said… I hate printers in general. Think “office space” level of hate. lol

[Dean_Rantala]

So I did some more trail and error and am close.

I changed my first layer height from .24 back down to .2.

I have my z-offset (in Orca) set to .04.

I downloaded a first layer test: 5 tiles that measure 25mm x 25mm x .2mm. A tile in each of the 4 corners of the build plate and a 5th one that prints right in the center.

Here is the interesting part: the 4 tiles in each corner print absolutely perfect. Every one turned out super smooth. One of the 4-corner tiles had just a ever-so-slight nib on the very corner - not enough to complain about really.

But the center tile… that one - while perfectly even - it still has a bit of that hairy/fuzzyness to it.

Here is an example of one of the corners:

And here is another:

Now here is the center tile:

These photos were taken as the plate had started to cool down, so can disregard where they are starting to separate from the plate - it was actively cooling as I took the shots.

But that last photo - you can see some of the hairys/fuzzys. Running my finger across the 4 from the corners feels SMOOTH, the center one feels ROUGH.

Is this a leveling issue? Maybe re-run the bed leveling auto routine again? Perhaps after letting the bed heat up to the 85c that I nornally run the printer at? Or would this be something else?

Or am I just being too picky now? lol

[dougl]

using calipers do they measure something just over .2mm thick? THAT is what you are shooting for because when you say you want something 1mm tall you don’t want it to be .8mm tall because the first layer is squished and not really .2mm.

I say a little over .2 because you are using a textured build plate and the texture will add some extra depth/thickness but in the hundreds of a mm.

[Dean_Rantala]

So I did a quick check with my digital caliper before heading to the office…

.28 for the 4 outer ones…

The center one.. erm.. hard to tell with all the fuzzy and nibbly garbage on it.. between .29 and .3 maybe?

So my understanding is this: the first layer is supposed to be “squished” onto the plate. Which seems (to me) that if I configure it to be .2, it should then actually be something more like .19 or .18. Likewise… if I measure .28, then the first layer should be assumed to be .3 or so. Or is this wrong?

Back to my actual measurements…

I have the z-offset configured at .04 and first layer set to .2. That accounts for .26. The other .02? Is this extra .02 just acceptable tolerance for this class of printer?

So I am trying to chase down a couple possible issues here:

1. Why is the first layer of poorer quality around the center of the plate -vs- the outer edges?

2. If my first layer should be closer to the set point of .2, I assume I can move the z-offset back down another .02. But at “0”, it was really messy before.

[Dean_Rantala]

I am going to find my machinist straight edge tonight and dig out the feeler guages to see how flat the bed and build plate both are, too.

[dougl]

if you have your first layer and all subsequent set to .2mm then that is what they should be. Yes you tend to want the first layer squished some but that does not mean significantly thicker and it surely should not be part of the calculated system. ie what’s typically done is increasing extrusion slightly, ie send more plastic out the nozzle but the nozzle hight is not changed.

If you are getting .28mm measured when you have .2mm set for the layer height then your Z offset is just about .05mm too high. The goal of the Z offset is to get your first layer thickness to match what you have “programmed” into the slicer( .2mm ).

As for quality of the print in the center, do you have the part fan turned off for the first layer?

[Dean_Rantala]

99% Sure the fan is off for first layer.

Once I get home tonight, I will move the settings back down and tweak some more.

-Dean