I have just changed to a direct drive extruder last night, (the pic is from the old one), so i don't think over extrusion, but I am happy to try anything you suggest. Exactly same thing is happening with new extruder and different filament PLA Carbon fiber, original blue pic was PLA+
When 3d printers get to a corner, they typically slow down. You go from being stable printing fast with a high pressure in the nozzle to suddenly slowing down and so they tend to overextrude on the corners.
One fix is to set the jerk and acceleration as high as possible without losing steps so that it doesn't slow down much. Another fix is to print slow enough that it doesn't slow down at the corners much. For example if jerk speed is 20mm/sec then you could print at say 35mm/sec and it will barely slow at all on the corners.
I just looked at your 3mf file and that's an ultimaker s7. Which does not have a direct drive extruder. Please send the project file for the printer that is over extruding the corners. If it is indeed the S7 then I recommend you disable accel control and jerk control. Those features reduce ringing but increase bulging corners and also slow down the print time.
10 hours ago, Phatwarren said:I have just changed to a direct drive extruder last night, (the pic is from the old one), so i don't think over extrusion
I hope by "just changed to a direct driver extruder" you're not talking about the Ender-3 V2 Neo in your .3mf file (did you change it after @gr5 downloaded it or was he looking at the wrong one to begin with?). Unless you bought and added a Sprite extruder, it very much comes with a Bowden extruder (but at least it's the one with metal parts, not the plastic one with a failure rate somewhere around 100%).
Regardless, nothing about a direct drive extruder prevents overextrusion - it gives you more control over the flow (and is much better at retracting) but has nothing to do with the actual flow rate of the filament, unless your Bowden extruder was having trouble grabbing the filament well enough to stop it. And if you did just add it - did you make sure to calibrate the E steps?
Bowden's are worse on corners like that - the bowden acts like a spring. There's a LOT of pressure - sometimes up to 15 pounds of force (around 8kg) at the feeder. The combination of the springiness of the bowden and the high pressure in the nozzle means it takes longer for the pressure to equalize to a new (lower) pressure when you slow down. Versus a direct drive.
9 hours ago, gr5 said:15 pounds of force (around 8kg)
Where did you learn to convert from barbarian units? 1kg = ~2.2lb (the rough conversion from barbarian units is 1lb = 450g (it's actually ~453.6g, but I said rough)) so the number in kg will always be less than half the number in pounds (in the case of 15lb, it's ~6.8kg).
Either way, I'm curious if it's much more if you're using 2.85mm filament. I like numbers that seem "fun fact" sort of ridiculous (and a Bowden extruder putting that much force seems ridiculous).
Hi Guys, It is an Ender 3v2.
I used the bowden extruder for that blue example and then added a Creality E.Fit Extruder 2 days ago.
I am using that .3mf file at the moment, printing 40 of those parts and they all have that consistent bulge on all the vertical corners.
Actually so consistent that I thought it may have been a setting I clicked in Cura to make it happen. Especially after the different materials did the exact same thing. (PLA, PLA CF, PLA+ and PETG)
WRT the E Steps of the extruder, whilst changing the extruder I was then directed to adjust the e-steps to 405.
Is there perhaps an extrusion setting I can change in Cura that I can adjust to mitigate this artifact, possibly do that Jerk and Acceleration thing gr5 was talking about?
Kind regards
Warren
Using the 3mf file you posted which is for an Ultimaker S7, I don't think it's possible to slice it and then print the resulting file (a "ufp" file). Even if you could get it to create a gcode file I don't think that would be printable either on an Ender.
I recommend you use a slicing profile for an ender printer. Not for an Ultimaker printer. I think that may improve your quality a lot! Even if it's not the exact right printer.
If that really is your profile, you should still remove accel control and jerk control. But first, you should switch to an Ender printer profile.
2 hours ago, gr5 said:Using the 3mf file you posted which is for an Ultimaker S7, I don't think it's possible to slice it and then print the resulting file (a "ufp" file). Even if you could get it to create a gcode file I don't think that would be printable either on an Ender.
It's not for any UM machine. Should be some warning toasts when you load the project, saying it can't find a profile for it (even though the profile for the E3V2 Neo was added in 5.7, better late than never I guess) and it'll load the models on the plate for whatever printer you have currently selected.
8 hours ago, Phatwarren said:WRT the E Steps of the extruder, whilst changing the extruder I was then directed to adjust the e-steps to 405.
Never hurts to check yourself. Creality's manufacturing tolerances can be somewhat generous.
8 hours ago, Phatwarren said:Is there perhaps an extrusion setting I can change in Cura that I can adjust to mitigate this artifact, possibly do that Jerk and Acceleration thing gr5 was talking about?
About extrusion settings, I hope you at least reduced the retract distance - not really applicable here, but a direct drive extruder requires a much lower retraction than a Bowden extruder (I use 0.8mm for PLA on my E3V3SE).
Acceleration and jerk can be found at the bottom of the Speed section of the settings, checkboxes for Enable Acceleration Control and Enable Jerk Control and a bunch of settings will appear if you enable them. The defaults in some profiles are ridiculous.
If I'm going for accuracy and have plenty of time I usually set acceleration to 200mm/s² and jerk to 4mm/s.
If I'm not then I still err on the side of caution and go for about 500mm/s² acceleration and 8mm/s jerk.
If I need something done quick and I'm not too picky about quality I go for about 1500mm/s² acceleration and 15mm/s jerk.
FWIW my E3V3SE can accelerate at 4000mm/s². I think. Creality's website says 5000mm/s². Manual says 2500mm/s². Using a gcode command to get information from the printer says 4000mm/s². All of those rates are waaaaaaaay too high for any realistic use and exist only so they can brag about how quick the thing can print a Benchy.
Also depends on material (TPU likes to go down slow).
Wow that is all good advice, thank you. I am definitely going to try those acceleration and jerk settings to see where I can go. All said and done this is a great learning curve as I develop my skills in this art.
WRT the printer settings on the profile, I chose Ender 3 v2 when I started printing with this machine and have not changed it since, (asper the pic), so I have no idea where the Ultimaker S7 profile would have come from. The only thing I have done differently was to download that new Cura Beta, but other than that Ender3v2 all the way.
Warren
23 minutes ago, Phatwarren said:WRT the printer settings on the profile, I chose Ender 3 v2 when I started printing with this machine and have not changed it since, (asper the pic), so I have no idea where the Ultimaker S7 profile would have come from. The only thing I have done differently was to download that new Cura Beta, but other than that Ender3v2 all the way.
D'oh! At least now I see why mine wouldn't load the printer profile for your file - I still have my old custom E3V2 Neo definition in my configuration folder so the "Startup Optimiser" plugin blacklisted loading the regular one. Fixed that. Still no idea what the hell @gr5 is doing to see an UltiMaker 😕
How are the un-filleted corners on your back coming out?
Would help to know if it's an "all corners" thing or just a "curved corners" thing.
Also heads up: it looks like you're trying to do the right thing by printing the initial lower slower than the rest, but the "Print Speed" setting is very misleadingly named: it prints the infill (where quality doesn't so much matter) at that speed and everything else at half of it. So everything else is going at 40mm/s and your first layer is doing 50 🙂 - I just set the "Print Speed" setting to double what I want everything to print at and enter the infill speed (same as the rest, for me) specifically.
(Your first layer should probably be doing something more like 30, at least that's what I do, but if you're not having any adhesion problems then don't worry about it)
For basic stuff like this I usually run my PLA+ (same brand as you!) at 60mm/s and while there is such a thing as "too slow" 40mm/s is well above that (but if you intended to print the whole thing at 80mm/s... I'd stick to 60).
Looking at the acceleration and jerk, they're actually pretty reasonable (500mm/s² and 8mm/s respectively) so while it certainly wouldn't hurt to do a test with them set lower, they shouldn't be causing you major problems.
If you stuck a direct drive extruder on that thing then you have to change the retraction settings - the defaults (which are for a Bowden extruder) are ridiculous for a direct drive. For PLA I do 0.8mm at 40mm/s.
Looking at it in the gcode viewer I see it's pretty much relying on the outer wall to do all the curving action:
This is very hard for the printer to pull off (although a little less hard for a direct drive, still hard) because it requires incredibly precise flow control (the curved bit is a teensy bit thinner).
Let's zoom in on one of the corners:
Yeah. That could probably explain overextrusion. It's not like it stops for every little bit but it is a separate movement it has to process.
Actually, that reminds me: please please please tell me you're printing from an SD card and not over USB. USB printing is a relic from the ages when printers were too dumb to even read a memory card. No guarantee commands will be sent fast enough over USB whereas it can not only get them as fast as it likes from its own memory card but it can look ahead and store them in RAM so it's never left wanting for a move command.
You could try setting Mesh Fixes > Maximum Resolution to something low like 0.01mm and see if it prints any better than it looks:
Although to sum it up with something I haven't actually said yet: the problem lies somewhere between the model and the laws of physics. The corner radius is way too low to be able to print accurately with a 0.6mm nozzle (and you can see what happens when it tries). Playing with (and by that I mean reducing) the jerk might make a difference because it'll make it do the thing slower (which allows for more precise flow control) but I wouldn't count on it.
Yes the back corners a also the same 'perfect' bulge.
Cool, let me set the Mesh Fixes to 0.01, and sadly yes, I have been doing everything from Cura on the PC via USB, I happy to try the card thing, just found it comfortable to click,click,click and the printer ran.
Warren
I just went back into Fusion now, seems that none of those edges have been rounded over, only the inside verticals, as the outside ones connect to the next bracket.
Well I don't know if it's Fusion doing it automatically or something (never used it) but all these edges are definitely fileted:
The only ones that haven't are the outside rear corners:
According to my measurements the fillets have a radius of about 0.32mm - way too low for a 0.6mm nozzle to handle. Barely possible for a 0.4mm nozzle.
The outside rear corners aren't helped by the Z seams being put on them:
You can change that by setting Walls > Z Seam Alignment to User Specified and Z Seam Position to back so it'll prefer the inside walls:
Also it may be the photo (and the fact that this forum crushes image quality) but it almost looks like the top and bottom are rounded. Zoom and enhance! Wait... this isn't TV. Resample and unsharp mask!
Just as a test... here's a cube. Print it and let's look at the corners. cube 20mm.stl
Printing a simple cube is a great idea. Having 6 points on each tiny corner may be too much for Marlin. The ender I believe has an arduino based controller running the firmware "Marlin" which has a buffer of 16 moves (gcodes) and having 6 on each corner uses a lot of those 16 moves but I suppose it should be fine but still it may slow quite a bit on those corners (thus overextruding). But I'm not sure. You'd have to watch it or video it to be sure. 6 points I suppose is normally fine since then you have a nice long move right after.
The point is the movement planner only can see ahead 16 moves and it doesn't know what's coming so it needs to be able to stop within the next 16 moves and if all 16 moves span just a few mm it will slow way the hell down.
Increasing (not decreasing as slashee says) the jerk usually helps overextruding corners to prevent if from slowing down too much. But maybe that's not the issue, not sure.
Increasing jerk and acceleration can also hurt vibrations known as "ringing" or "ghosting" but I don't see that on your print.
Yes the inside verticals are definitely fileted, but the joke is they look just like the outside ones that will push up against the next model, that are supposed to be square.
I am keen to print that cube for you, just in the middle of a big print then I will do it next.
This is what I mean by inside and outside, the outside edges were left square to press up against the next bracket...
11 minutes ago, gr5 said:Increasing (not decreasing as slashee says) the jerk usually helps overextruding corners to prevent if from slowing down too much. But maybe that's not the issue, not sure.
Lowering it to see if it makes it worse counts a valid experiment 🙂 But I'll concede that one.
One important thing which I should have brought up by now: make sure your machine is properly tuned. I don't mean levelling the bed and setting the Z offset or measuring your E steps (although those are all good things to do) but check your belts and screws to make sure they're at proper tension. (Also, don't adjust these while your machine is on.)
Belts (X and Y axis) need to be taut but not stretched to their limits, the best description I've heard is "like a guitar string" - you can pull it a little and it'll snap right back.
The Z screw usually isn't a problem unless it gets full of crap (I use an air duster designed for cleaning computers to blow stuff out of it) or needs to be lubricated. Usually it's not a problem. Just make sure you can turn it freely and it doesn't feel "dirty" - should just screw smoothly.
The wheely bits that hold the X axis gantry to the frame can be annoying, especially because if they're not even it can result in your gantry getting lopsided. Better printers have a Z screw on both sides to prevent that. The E3V3SE has screws on both sides but they cheaped out on the implementation ("cheaped out on the implementation" - Creality in a nutshell): instead of having a motor driving both of them, a motor drives one and then there's a belt at the top of the from which makes the other one turn. Errr, anyway, back to the wheely bits. They're a bit annoying to adjust because they use helical nuts meaning it's not one way tighten, one way loosen. It's turn and it'll tighten and loosen as it feels like it. They should be tight enough that you can rock it a teeny bit up and down with one finger and it settles back in place.
In case it helps (or you're just curious), jerk in hopefully not techno-babble:
It's not like any jerks you know (like that guy across the street who mows his lawn three times a week and no it hasn't noticeably grown since the previous time and yes I have tried submitting a noise complaint but since it's during normal "business" hours it's not bad enough) or pulling stuff quickly.
At corners, in a perfect world, printers would slow down, stop at the corner, and then accelerate off in the next direction and you'd have a perfect corner.
In the actual world, if it did that, then all the time it spends there would give you overextrusion in abundance. So to avoid having to come to a stop, we have jerk: it's the maximum speed change in the direction that it's travelling (i.e. making a left or right turn) - that the printer can instantly make to avoid having to come to a stop
It's not the only factor which comes into play though: it has to slow down to the jerk speed and then accelerate up again from that, which takes even more time, so if the printer isn't correctly controlling flow, more time to be overextruding.
Lower jerk:
- More accurate corners
- Takes longer
- Less vibrations so tall and/or flimsy models won't wobble as much on bed slingers (which the E3 V2 Neo is, on the Y axis)
Higher jerk:
- Very high jerk values can result in the print seeming like it cuts the corner - the head doesn't, but if you start pulling the filament in a different direction before it's had time to set even a little, it'll pull it with it and give you a diagonal
- Extreme values can result in a motor receiving such a sudden shock it could skip a step or two so that higher layers will be printed slightly off to the side of the previous ones (it's called layer shift)
- Can lead to artefacts such as ringing or ghosting, as @gr5 said
There's no correct value. Depends on what you're printing, the material you're printing with and your printer. It can be sort of trial and error. And remember: small scale testing is your friend. If you find a bit which is consistently bad, then cut that out of the whole model and just print that bit.
What slashee said about jerk is correct but realize that there are physics terms: velocity, acceleration, jerk but when we talk about 3d printing it's a special version of "jerk" that doesn't match the term in physics. Jerk in physics has the unit meters/sec/sec/sec and jerk in Marlin firmware is in the units mm/sec. It's a velocity change.
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Good Evening Folks
Made a few of those cubes with different settings and learned lots in the process.
When I got to just a plain Cura PLA profile the corners seemed to square up with a 200C nozzle temp, so I decided to drop the temp from 210C to 190C, this helped a lot. Also whist testing the acc and jerk it seemed that faster for this filament was better so the final cube is also 1000 and 10.
Thank you for all the discussion we have had, I really leaned lots about the printer and it's workings.
I hope others watching the chat also learned from all your advice
Cheers
Warren
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Slashee_the_Cow 409
Howdy! If you could share a Cura project file (.3mf, get it ready to print then go to File > Save Project) of something which shows this phenomenon - like your example - that could help.
It looks like it could be overextrusion though, to my somewhat-trained eye. Have you calibrated the E steps on your printer? (There's plenty of tutorials on YouTube for how to do it)
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