New user: print quality issues

[EXEYE 0]

I'm very new to 3D printing (using an Ender 3) and am overwhelmed by all the lingo especially as used in the descriptions of settings.  I'm trying to print things with significant overhangs and need to figure out what settings will improve print quality.  Trial and error is impractical given the hundreds of settings and unlimited variations of settings, and the fact that it takes several hours to change something and do a test print.  I've also found that I get different results each time I print something without changing settings.

 

I suspect that some of my problems are related to filament feeding.  I'm trying to print a guide for the filament which should help, and I've ordered a better feeder and a ball-bearing reel support, which should also help (if this is in fact part of the problem).

 

The attached pictures show two prints.  One is a small parts box, which I'm printing right side up.  The pictures show two prints of the same item, upside down from the way it was printed.  The bottom of the box is raised a couple of millimeters off the bed by four feet.  This raised bottom is a mess.  It seems to be being printed as infill.  Shouldn't it start out as a solid surface?  What setting changes might improve this print?

 

The second set of pictures shows a filament support arm I am trying to make.  The bottom is nice and smooth, but the top is very uneven, the "inside" has infill showing and there are gaps all over.  Any suggestions as to how to improve this?

 

I'm not looking for information that is already available; a link will do.  But I've spent a lot of time searching and have yet to find anything that explains what might be going on.

 

Thank you!

[ChaosLord10 0]

The pock marks on your filament guide may be caused by an extrusion issue. Meaning your filament may not have a nice even flow. This can have several causes. If your filament is not stored in a dry environment, it could have moisture in it. Another simple thing to check is your nozzle. If it is used or old, it may be causing under extrusion. More in depth fixes include calibrating your extrusion settings. I’d start with checking your nozzle, then get a full bed level. Can’t hurt to do it multiple times. Then pick a small print. Like a 6 sided die or something (you can find one on Thingiverse for free), and play with your temperature. Print a few times to find the right temperature for the material you are using. Also be sure to store your material in a dry environment. You can pick up a water tight bin and some of those “do not eat” silica packets at walmart. (I just save them whenever I have new PLA delivered). Anyway, that’s something to start with.

[GregValiant 1,305]

Yes, intermittent under-extrusion and some of it is very severe.

The #1 problem with under-extruding Enders is the plastic extruder arm.  They all fail.  100% failure rate.  They have been known to be delivered broken.

This is the underside of a failed arm.

The only fix for that is an all-aluminum extruder.  They are available all over the place.  I got the one for my Ender 3 Pro from Creality.

 

Have you calibrated your E-steps?  It is necessary on Enders.  When lines in the gcode file ask for filament the printer must deliver exactly the right amount of filament.  The Extruder Steps/mm can be adjusted to insure what is asked for is what it gets.  I'm sure CHEP has YouTube videos in his Filament Friday's series.

 

Another common problem on Enders (they all share the same hot end) is a gap developing between the back of the nozzle and the end of the bowden tube.  Long retractions can pull molten plastic into that gap and it makes a sort of o-ring there and impedes the incoming filament.

The fix for that is to:

• Heat the hot end to around 200°.
• Pull out the filament.
• Remove the nozzle (carful - it's hot) using a correct wrench and NOT a pair of pliers.
• Remove the bowden tube from the fitting on the hot end.
• Shove a calibrated piece of coat hanger (about 1.5 to 1.6mm diameter) down through the heat exchanger and heat block (in a pinch you can use a 12" piece of filament but you have to move fast because the hot end is hot).  I'm betting you will push out a plug of plastic.
• Cut about 5mm off of the end of the bowden tube using a decent single edge razor blade or equivalent.  The cut must be as close to exactly square as you can get it.
• Put the nozzle back in and gently tighten it, then back it off 1/2 turn.  The hot end must be at least 180° for this as any plastic that has gotten into the threads needs to be soft.
• Shove the newly cut bowden tube into the hot end and while holding it down against the back of the nozzle - put the locking clip back onto the fitting.
• Gently tighten the nozzle.

You should end up with the bowden making a decent seal to the back end of the nozzle.  It should be good until the next time it happens.  The bowden tube is a "consumable" and with every trimming it will keep getter shorter until it needs to be replaced.

 

With your model loaded (either one) and Cura set up ready to slice use the "File | Save Project" command.  Post the 3mf file here and I'll take a look.  

[EXEYE 0]

Thanks for the replies.  I expected to get an email when someone replied which explains the long delay in my response.

 

I replaced the extruder with an aluminum one, which did help eliminate the gaps.  I also calibrated the steps/mm, which was way off.

 

I haven't done your recommended fix for the Bowden tube, but will do so in the next day or so.

 

I still have trouble with the bottom of the boxes I am trying to print.  I've attached a picture of the bottom side of the print showing all the squiggles I get.  There is also a picture of a box right side up, the way I am trying to print it.  I've tried various settings and temperatures and nothing seems to make any difference.

 

I've also created and attached the 3mf file per your instructions.

 

Thank you very much for taking a look and for any suggestions you may have...

CE3_hf_small.3mf

[GregValiant 1,305]

Here ya go.  Your model needed support under the base.  You will need an exacto knife to break the support loose from the model.  It's an acquired skill.  So is not breaking off the little legs when you remove the support.

The other item in the model file is a support blocker to keep support from building for the little overhang at the top.

GV_hf_small.3mf

[EXEYE 0]

Hi Greg,

 

You were right about needing a support (and about breaking off the little feet!).  The attached picture shows an almost perfect box, aside from the missing foot.  But I think I've figured out how to avoid that in the future...

 

However I have a new problem that has me stumped.  When I loaded your 3mf file and tried to print it, the printer moved to a position about 14mm above the build plate, tried to draw the purge line, then moved to the upper right corner of the build plate and started extruding filament very fast, faster than the feeder could feed.  I tried everything I could think of (or find online) to overcome this, with no luck.

 

Finally I deleted the cura folders in AppData to reset everything back to the defaults (why is there no way to do this from within Cura?), loaded the original stl file and manually set all the changed parameters, drew another support blocker, and it printed fine.

 

Then I saved the project as a 3mf file, reloaded it, and tried to print another box.  This time it did what yours did, but at a height of about 5mm.  Then I reloaded yours and it did its thing at a Z of 14mm, as before.

 

What this acts like is that saving (or loading) a model as a 3mf file corrupts it.  Next I should try to figure out how to save the settings (a "Profile"?), reset everything again, and start from scratch, avoiding the save/load project stuff.

 

But first I thought I'd ask you if you knew anything about this.  I am using Cura 5.0.0.  I've wasted spent enough time on this already today.

 

Thanks again for all your help!

[GregValiant 1,305]

What might be happening is that there is a bad sector on the SD card.  Some commands are being ignored and the printer just moves to the next one it can understand.

Try re-formatting the card to FAT32 (quick format is fine) and then try again.

 

I have changed the my default StartUp Gcode (that you will find on the printer in that 3mf file).  It does make a quirky move at the beginning before moving off to start the skirt as I was trying to wipe the nozzle off on the purge line so it wouldn't string across the build plate.

 

Cyano-acrylic Super Glue works really well on PLA and PETG.  Those legs might be too small, but if they were a tad bigger then printing them separate and then gluing them onto the box is a definite option.  A lot of people ignore that sometimes it is more efficient to print separate pieces of an assembly and glue them together than it is trying to do an "All At Once" part.

 

The bottom of the box looks pretty good.  Because the nozzle can't "squish" into the support very well the extrusions tend to stay round instead of being flat.  That's part of the FDM thing.

 

I've been experimenting with making support weaker so it's easier to remove.  Running the Support Intrface Flow at 90% works pretty good for me.  I'm able to remove the support easier which makes it slightly less likely that I'll cut a finger off.

Edited July 18, 2022 by GregValiant

[EXEYE 0]

Greg,

 

Thanks for the quick reply!

 

I'm not using an SD card; I just have the printer hooked up through the USB port, which has worked well so far.  I should probably try using the SD card to rule out the USB, but if the USB were flaky I'd expect random problems, not something repeatable.

 

The support comes off easily if I put the spatula thing on it (between the feet) and give it a careful whack.  I broke one of the feet off trying to get the box off the baseplate; next time I'll try on the support instead of the feet and see if that works.

 

I'm very suspicious of your modified startup gcode.  I guess I'll have to find a gcode reference manual and start figuring it out.  Could this be a problem caused by my printer having newer firmware than yours?

 

I've been a programmer working with CAD systems since 1972 (!) and over that very long period I've developed drivers for all sorts of devices, from pen plotters to laser printers to CNC milling machines.  So gcode is going to be second nature for me.

 

I'll keep you posted...

[GregValiant 1,305]

Ha.  I've got you beat by 4 years.

The startup gcode for any printer comes from the Printer Definition file.  A project file will over-write the StartUp Gcode of an installed printer if you select "UpDate Creality Ender 3" when opening a 3mf project file.

So what you can do is open that original CE3_hf_small.3mf file you posted and let it update your installed printer.  You will get your old Start and End gcode back.  An alternative is to install another Ender 3.  You can always change the printer name.

 

I originally wrote this for an analog computer (just kidding).  It moves most of the LCD menus and controls to a connected Windows computer.  No more clicking that damn button.  It includes Auto-Tune to adjust your hot end PID, a function for calibrating the E-steps, and a post-processor to add a cooling profile to a gcode file.  It doesn't print over the USB but rather controls SD card printing through the USB.  There is a readme file, it will install an icon on the desktop, and there is an un-install utility.  It is unsigned because I'm cheap.

 

Greg's Toolbox

 

 

 

Edited July 21, 2022 by GregValiant
Update Zip File

[EXEYE 0]

Hi Greg,

 

I followed your instructions and got my old start/end code back.  It's now printing the boxes pretty well.  I'm also learning more about how Cura is intended to be used.

 

I installed your program and it looks pretty nice.  You've lost me on some of the terminology.  What does PID stand for?  What is a cooling profile?  Why don't you print over USB?  It works flawlessly from within Cura, and it's so much easier.

 

You're right that those damn little feet usually break off.  I glued one on, which took a half hour, but I'm sure I'll get better with practice.  If I had a way to edit the stl file I could reinforce the feet by adding a fillet to where they attach to the box..  Maybe if I increased the infill to 100% it would make them stronger.

 

The first layer of the support included a 10mm flat surface around the outside of the support, presumably to increase adhesion.  but my problem isn't not enough adhesion but rather too much, so I turned it off.  We'll see if that helps.

 

I'm getting to a point where I can depend on it printing a box perfectly.  Next I want to try printing them 4-up or 9-up, so it can run all day.

 

-jimc

[GregValiant 1,305]

"What does PID stand for?"  It's either "Pelvic Inflammatory Disease" or "Proportional, Integral, and Derivative".  Since we're 3D printing it's probably the latter.

The hot end is controlled by PWM (another one) which is Pulse Width Modulation.  Tuning the PID is a sort of synchronization between the heater on the hot end and the thermistor that is next to it.  It effects how accurately the hot end stays at it's set temperature.  If it isn't "right" for your heater/thermistor combination then the temperature can bounce up and down.  The bed on your printer is controlled by a regular thermostat and so it is "bang-bang" on-and-off rather than PWM.

 

"What is a cooling profile?"   I use both PrusaSlicer and IdeaMaker once in a while.  IdeaMaker has a function for adding custom cooling to a print.  I took it a bit farther and you can change the cooling at different layers, or by feature type (Walls, Skins, Support, etc.)

(NOTE:  I was adding a cooling profile to a print yesterday and came across a bug.  I replaced the Zip file above with the new version with the bug repaired.  You can download the new version with the link in the previous post and re-install.)

 

Cura essentially turns the fan on and it stays on.  When I print with PETG I found that some cooling at certain places (like when a large horizontal hole closes up) require cooling, but then I shut it off again.  That's what that function does.  You can turn the fan on at layer 25 at 100%, then at layer 30, drop it to 50%, layer 40 100%, and then at layer 50 change it to 0% to shut the fan off for the rest of the print.

Because my post-processors work after the gcode has been built, they open the original gcode file and write it into a new gcode file while making the changes you asked for.  For he Cooling Profile, if there are M106 lines in the original gcode file they all get removed and the new M106 fan lines go in.

 

"Why don't you print over USB?"  It works flawlessly from within Cura, and it's so much easier."  You are new to this aren't you.  Bad things can happen during USB printing.  In particular is Microsoft kicking out a midnight update, shutting down your printer, and killing your 15 hour print.  Couple that with possible stuttt-ttt-ttt-ering because of buffer under-runs, and missed commands because of buffer-overruns, and M105 being misread as M1 "emergency stop" so no, I don't print over the USB.

 

"If I had a way to edit the stl file..."  You are on Windows and MS 3D Builder should be on your computer.  It isn't intuitive, but you can alter STL's quite well.  It can also repair model files that might have "non watertight" or other errors.

 

"The first layer of the support included a 10mm flat surface around the outside of the support."  That was the "brim".  You can also opt for  Skirt or Raft (raft is very thick and I never use one).  There is also a "Support Brim" that can help stabilize tall skinny supports.

 

 

Edited July 21, 2022 by GregValiant

[EXEYE 0]

Thanks for the explanations!

 

Yes I'm new at this.  I'm printing small simple things that don't take particularly long, so the risk of my computer rebooting during a print is low, and the consequences minimal.  But I am wondering if USB communication errors could be happening.  USB is pretty robust, unlike things like RS-232, so the odds of errors getting through are near zero.  I send a lot of stuff over USB and I've never seen a problem that could be attributed to communications errors.  But I'll try using the SD card and see if it works better.

 

Thanks a lot for the tip on 3D Builder.  I will try it, even though MS apps are usually awful.

 

I've been struggling with a bunch of problems but have been trying solutions I've found by searching.  I had pretty bad stringing but seem to have solved that (I'm not sure how) and have been getting nozzle clogs very often.  My latest try is the addition of a "filament filter" to hopefully keep dust and cat hair off the filament which may be causing the clogging.

 

It's slow going and I've used up most of a roll of filament so far which has yielded maybe a half dozen useable boxes, but I do seem to be making progress.

 

-jimc

[GregValiant 1,305]

"USB is pretty robust, unlike things like RS-232"

But in the case of 3D printers (most anyway) what we deal with is a USB port configured as an RS-232 emulator.  It's acting as a serial port.  Over-runs and under-runs remain a possibility.

I mentioned the "M1" issue.  Cura and Pronterface both sent M105 at timed intervals and would check the printer response to insure that the port was open and active.  If the receive buffer on the printer was almost, but not quite full, the M105 gets truncated to M1 which is "Emergency Stop".  You look at your printer and it has halted with "Click to resume..." on the LCD.

Octoprint/RaspberryPI work well for remote printing.

The SD card is simple and is what the printer was really designed to read from.  When the printer needs another line of code it grabs it.  There is no need to sync the speed of transmission through the USB to the printers appetite for lines of gcode.

[EXEYE 0]

Ok, now I understand why USB isn't recommended.  It's working well for me though (I think); I haven't had any M1 problems.  I wonder why Octoprint/RPi works well; doesn't it connect via USB too?

 

I installed MS 3D Builder (MS requires that it be installed through their "app store", and app store apps don't have a way to put a shortcut on the desktop.  I found a way anyhow.  I hate Microsoft -- I think they have a whole department devoted to making things difficult to use).  I was able to (barely) use it to modify my box files so as to reinforce the feet a little.

 

I have two new problems.  I'm now trying to print a larger version of my yellow boxes, and it has pretty serious curling at the corners.  I reduced the bed temperature to 40° per suggestions I found online but that seems to have made it worse.  I'm not sure what to try next.

 

My other problem is that my nozzle clogs after a few (3-6) hours of printing.  That means I can usually print one copy of my 4-up small boxes or one of the medium boxes, but it will stop printing partway through the next thing I print.  I've tinkered with a few things, primarily nozzle temperature, with nothing I've tried helping.

 

Any suggestions?

 

Thanks!

 

-jimc

[GregValiant 1,305]

"...I think they have a whole department devoted to making things difficult to use..." .

Yes they do.  A special department for things like "Everybody is used to that so let's change it."  and then the supervisor steps in and says "Not enough confusion.  Let's move it to a different menu too."

The world didn't need anything beyond Windows XP, and Excel and Word 5.0.  

Enough.

 

The lock fittings that hold the bowden tube in place have little knife-like teeth built in that grip the tube.  As the print head moves back and forth on the X beam the tube rotates in the hot end fitting.  Those little teeth keep going deeper, retractions and primes push and pull the tube, and pretty soon it's sliding up and down and there is a gap between the end of the tube and the nozzle.  Hot plastic gets pulled into the gap and forms a sort of O-ring seal around the incoming filament.  Extrusion starts to suffer, but the problem is rarely bad enough to cause missed steps by the extruders.  It's just an under-extrusion problem.  I don't think I've ever had an actual clogged nozzle.  Hot end?  Oh yeah.

 

So you need to warm up the hot end to 200 or so, pull the filament, pull the bowden out of the hot end, carefully remove the nozzle without burning yourself (using a proper wrench and not a pair of pliers).  Then you can shove a properly sized piece of coat-hanger or bailing wire down through the hot end to push out the plug of plastic that is probably in there.  (You can use a 300mm piece of filament as a pusher but you have to move fast as the hot end will tend to melt the pusher piece.)

Cut 5mm's off the bowden tube.  The cut you make must be as exactly square as you can get it.  I use an old heat break from a previous hot end as a razor guide.  Single edge safety razors are the best tool for trimming the bowden.

 

Put the nozzle back in.  Gently tighten it and then back it out 1/2 turn.

Push the bowden in down tight to the back end of the nozzle, then lift the little flange of the locking ring and put the plastic clip in place to hold the lock ring up.  Then gently tighten the nozzle that last 1/2 turn to snug it up to the bowden tube.

 

That whole process is regular maintenance.  Bowden tubes are a consumable item but they only need to be trimmed back about 5 or 6mm each time.  I get about 40 hours of printing before it starts to act up.  I always do the maintenance before I start a long print.

[EXEYE 0]

Hi Greg,

 

Yes that's what I've been doing, except for the 1/2-turn procedure, which I'll do from now on.

 

Do you recommend a specific kind of Bowden tube?  I replaced the stock one with this one:  https://smile.amazon.com/dp/B09N7B8NKF?psc=1&ref=ppx_yo2ov_dt_b_product_details.

 

As always, thanks for your help!

 

-jimc

[GregValiant 1,305]

That's the one I use.  It has better temperature resistance than the stock tube.  I print a lot of PETG and it holds up.

[EXEYE 0]

I keep trying different settings trying to solve various problems,  The most recent problem is serious curling especially at the feet.  It mostly affects the support area and the feet.  This is an example:

 

I made some more changes and got a print that looked like a pile of spaghetti.  So I decided my setting changes had gotten out of control, and reset everything except turning on the support back to the default.

 

It seems to be printing ok except that the curling is bad and the feet aren't sticking to the baseplate.  Here is the start of a print with the new settings.  Note that the feet (in the corners) are just crumbs:

 

I've replaced my baseplate with a Creality glass one.  This has made it pretty easy to pop the finished prints off the baseplate but seems to have caused trouble getting the first layer to stick, especially where the feet are.  Any thoughts?

 

I'm sorry to keep bothering you with questions, but I do do a lot of searches for the problems I have and try the suggested fixes.  The suggestions are often ambiguous, like "try raising or lowering the bed temperature".  Your advice is usually pretty specific, and usually works.

 

Thanks, as always...

 

-jimc

[GregValiant 1,305]

It's tough to troubleshoot without being there to see what is happening.  I try to explain what I think is going on so the user has a better chance of figuring out the problem.

 

Those feet have very little surface area to attach to the build plate.  A brim might be a better choice.  You can set the brim distance so the brim isn't attached to the model so well.  Start with 0.1 brim distance.

 

I don't recall if you are using any adhesion promoter.  A light dusting of Extra Hold Hair Spray can help.  I use Aqua-Net.

Another thing that can happen is the first layer is too tall because the leveling is off by a bit.  In order to get enough squish and glue the filament down you can try setting "Initial Layer Flow" to 105% or even 110%.  It's a crutch but it can be a very effective crutch.

 

When you are troubleshooting you don't have to print the whole model.  You can tell right away if it isn't what you wanted or expected.  Just abort the print, make limited changes within Cura, and try again.  As you have noticed, a lot of changes at once and you can't tell what helped and what hurt.

 

Looking back at your very first image I can see that the feet hit the bottom and there is a sharp corner on the inside.  If that was a radius or a chamfer they wouldn't be so prone to breaking off.  I don't know if your design will allow that though.

[EXEYE 0]

On the small boxes I did use 3D Builder to smooth the transition from the feet to the bottom surface, which helped keep them from breaking off.  I never did figure out how to get the support to break off from the bottom cleanly, but I got good at cleaning them up with a Dremel tool and they're good enough.  I've made enough of them for the time being.

 

I've moved on to making boxes for the bigger parts cases.  These are similar in dimensions to the small ones but are about twice as high.  That makes the wall thickness more important.  The little boxes have very thin walls which is pretty much ok, though it would be better if they were thicker.  The bigger boxes seem to have even thinner walls, so that they very easily crack.  I need to figure out how to make them thicker.

 

I'm not sure what a "wall" is.  Here I'm just using it in the conventional sense, as meaning the sides of the box (I'll use "sides" for this from now on).  I don't know what Cura means by "wall".  In particular, I don't know if the model specifies a thickness for the sides of the box, and if that means that Cura considers the sides as consisting of an inner wall and an outer wall.  I've tried making the wall thickness very large, like 5mm, but still get very thin sides.

 

Below is a picture of a partially-printed large box, with the measured thickness of the sides marked.  The 1.44mm side is perfect.  The 1.33mm side is too flexible and looks to have infill.  The two 0.70mm sides are very thin and fragile.  I've also attached a 3mf file used to print this partial box.

 

 

What I need to know is whether there are settings that would give me the thicker walls I need, or whether the model needs to be changed.  If so, I guess I'll have to study up on 3D Builder.

 

Thanks!

 

-jimc

thick small half.3mf

[john3m 0]

I enjoyed reading these posts. I have the Ender 3 s1 pro can i get a link to the correct aluminum extruder

Edited August 6, 2022 by john3m

[john3m 0]

found the correct one

[GregValiant 1,305]

@EXEYE,

If you think of it as "models have features" it might be easier to get your head around.  Your boxes have vertical features that enclose a space.  (Consider the space as a "hole" in the top surface of the model.)

 

Let's say we have Cura set up for .2 layer height, .4 line width, 3 walls, and 4 top/bottoms (skins).

Your vertical features have an outside surface that faces outboard, and an outside surface that faces inboard.

Cura will try to do loops around those features.  Each loop is considered a Cura "wall".  If there is air on one or both sides of a wall it is considered an Outside Wall.  If there is model on both sides of a wall it is considered an Inside Wall.  In the Cura preview, Outside Walls are red and Inside Walls are green.

If your vertical features were 5mm thick Cura would put an outside wall around the inside of the hole and an outside wall around the outside of the model.  Those would be backed up by two inside walls.  The remaining space gets infill.

The model ends up with 3 .4mm walls around the outside and 3 .4mm walls around the inside with a gap of 2.6mm for infill.

The thickness of the vertical features determines what will fit.  In the case of your model, the long sides of the feature only get one "Cura wall" loop which by definition is an outside wall (air on both sides).  The short sides of the vertical feature gets two outside walls (1 facing out and 1 facing in) and two inside walls.  There is no room for infill.  (The chamfer on the corner gets an extension of the long outside walls and so the middle line there is red.  (That's part of the variable line width capability of Cura.)

 

If you want the long portion of the vertical feature to be thicker, you should add thickness to them in Cad.  It looks like the boxes will nest.  In that case the upper "female" portion would get thicker on the outside.  The lower "male" portion would get thicker on the inside.  Because of that difference between the upper and lower portions, you really need to do the change in the CAD software rather than trying to make adjustments in Cura.

 

 

 

Edited August 6, 2022 by GregValiant