yellowshark

Well I guess layers will start on the outer layer if one were to specify walls before infill and outer wall before inner wall(s). Also I cannot but help think, never having done it, that specifying 0.4mm line width with a 0.8mm nozzle is not going to help. Certainly the result is up the gumtree. Given that you seem to have some dubious settings it will help us if you post all your main and relevant settings, rather than us making assumptions and guessing.

Interesting post! I do not have the benefit of your background or experiences but I am a long gone software developer, ranging from assembler to Cobol. Yes old stuff but the fundamentals of software development broadly remain the same, just the tools and audiences change. The more complex one makes a subject, whether necessarily or unnecessarily, the more difficult it becomes to deliver clean code. Probably more importantly the more difficult it becomes to modify and deliver clean changed code. A generalisation would be that new functions work but bugs are introduced to existing code that was clean – it is just too complex to understand all ramifications of change and beyond one’s financial/operational capabilities to test everything that has not changed ( or so your thought!). At the moment I am stuck on Cura 2.7 (which for me works fine) whilst I await a clean version of 3.n. Does 2.7 produce better models than 15.04? For the most part, for me, probably not. But, as you say, there are more options which give you more control and if nothing else should help one overcome problems more easily. So is Cura now more complex than it needs to be? (Anyone from Ultimaker is welcome to shoot me down in flames for any wrong assumptions here). There are some fundamentals. The decision to create the new software (was it Pink Flamingo back then?) would have been driven by a variety of influences. There was a new printer in the labs to support, importantly with dual extruders. There was a new extruder system and coded reels of filament to support. Probably the architecture of the old Cura software did not lend itself to what Ultimaker wanted to do and the decision to throw away the old software was taken. Maybe, above all of this, Ultimaker saw that the market needed to change. It was populated mainly by techies and difficult, without help and that level of technical capability, to produce decent quality results quickly without some considerable experience – the learning curve was quite steep. Ultimaker wanted to move the market to a more plug ‘n play level; just compare laptops now to pre Windows or even early Windows PCs. I cannot remember the last time I reloaded the Windows O/S whereas with W95 it was every 6 months at least. Just consider how much functionality they have added to try and make this goal achievable if you have an Ultimaker 3. So yes the subject is more complex and no doubt so is the code, although hopefully better architected. I for one would not criticise them for this; indeed I applaud them for embarking on such a change. Just think of the increase in productivity if your engineers each had their own printer and with a few key depressions could produce their own prototype there and then, not having to rely on people like ourselves. And whilst there are now all these additional settings to keep the techies happy, their challenge going forward will be to gradually automate everything, remove all those techie settings, so we are all just making a few key depressions!

Lol I do neither/ both. I decide how many layers I want and then convert that to mm. No I cannot defend that or promote it; it is a bit like eating Weetabix for breakfast, although I can defend that ?

With a 0.8 nozzle (3 years ago) I ran .300 layer at 40mm/s with a temp of 210. I suspect that these days I might run that cooler as in general I print cooler now than I did back in my early days. Then again I seem to printing 10 degrees or so cooler than you, although I have no idea what speed you were using; there are a number of variables so nothing is gospel although I think about 10 degrees is the limit, beyond that I would be suspicious of something being wrong.

... sorry,that was for PLA; I use ColorFabb and Faberdashery; Ultimaker could be different.

It depends also on your print speed which you do not mention. Your optimum temp. will depend on your printer, your filament, the colour of your filament. And your optimum temp. could easily vary by 5 degrees either way from my optimum. My definition of optimum is the coolest temp. I can print at without under extrusion or any negative impact on the surface quality. With .3mm layers and a .4mmm nozzle at 30mm/s I would be in the region of 195-200 depending on filament

There is absolutely no problem in printing 0.3 layers with a 0.4 nozzle; I have been doing it for 4 years plus. Just remember that the higher you raise the volume per sec. flow the hotter you need the extruder. So with the same settings .3 layers will be a greater volume than .2 layers. Not sure about the 0.8 nozzle, certainly no expert on that. Again with the same settings you will be pushing through twice the volume and the feeder speed will be doubled but your extruding orifice is twice as large so I assume the pressure will be the same but whether you need any increase in temp. I have no idea really. Checking back 3 years ago when I last used a 0.8 nozzle it looks like I did not increase the temp.

Hi @geert_2 I agree with you; I always always print two or more copies if the layer print time is too fast, for the reasons you describe. I suggested setting the layer print time to 10 secs just as an investigative step, although I did not make that clear, of course a stop watch is an easy alternative! Love your idea of inverse models?

Good luck! Strange that the PLA is specified at a minimum temp of 210. I just checked the ColorFabb site and they recommend 195 and I have gone down to 190 without problem, that was probably.100/.150 layers at 30mm/s

Hi, I have not seen the other thread(s) on this...... but modifying the flow is unlikely to fix dimensional error unless it is very very small I suppose, no real idea, never tried it. If you print a 100mm line and your steps are under by 10% then that line will be 90mm thereabouts and flow will not fix that!

Ok two things. Firstly; now this does differ between printers and filaments BUT I think you are printing too hot. Using .200 layers at 30mm/s I would probably use 200 maybe 195. 220 is definitely too hot and is probably having an impact on your small piece. So take your temp. down as low as it will go, i.e. until you see under-extrusion and then push it up 5 and you should be fine. The small piece. I suspect your layer print time with this is too short and so the printed layer is not cooling fully before the next layer is printed on top of it, so you get squelch. Having such a hot nozzle (220) will not help but I suspect lowering the nozzle temp will not fix this problem. In Cura, under the Cooling section, set your minimum layer time to 10 secs. and minimum speed to 10mm/s and tick the Lift Head option. When you print the the piece if the nozzle lifts then you know your layer print time is less than 10 secs. You now have 2 options. Just let it print like this but it may be better to extend the layer print time by printing a second or third copy of the piece. Also you said your print speed is 30mm/s, that is good but make sure all your printing speeds are set to 30mm/s (excluding 1st layer).

Hi my Cura is older than 3.1.1 but I think you will find this in the firmware not in Cura - it certainly is in my non UM printer

Do you mean you extruded the filament not printing on a bed, but just catching it from the air? Wouldn't it stretch because it is still soft / warm and it just hangs there? Hi @SandervG, that is a fair point. What I do first is to extrude 30-40mm to ensure all is extruding well and as it should be, which does mean that on the first cut it is not totally hanging as it is laying on the bed before the cut is made. BUT that does not apply to the subsequent cuts (although as I said above the measurements were cconsistent). I do not think that measuring it printed on the bed is reliable as that will depend on how squished you have the filament set to via the bed to nozzle distance. Visually it looks right, i.e. once the first tens of mm have been extruded the width of the extruding filament, from the nozzle tip to the bottom looks consistent BUT that is not the same as using a vernier! I guess the good thing for me is that this "stretched" filament was fatter than the specified nozzle diameter and using .45 was better than using .40. Your point though does make me think that I will have another play and maybe try 0.47 or even 0.5 and see what happens.?‍?

Oh dammit, @LaserBrain, my comments were based on your test cube but if your are printing circular geometries then the inner diameter will have a tolerance close to what your stating , i.e. smaller; of course you may already know that ! but I just wanted to be clear.

Whilst I have not done extensive testing I think I agree with you @Jakeddesign on the 7/8 nozzle diameter. Whilst I have 0.4mm nozzle I measured that it was extruding a diameter of 0.45. When I say measured I did this by manually extruding 10mm of filament and cutting it off and measuring the diameter. I consistently got 0.45 with a couple of +/- 0.01 mm variations, During my testing and configuration work I found I had greater accuracy setting the line width to 0.45. Now, I am not sure on the implications of this but I could not set vs 2.n to have a nozzle size of 0.45mm as when you exit the dialogue box Cura rounds down to 0.4mm - so you either have 0.4mm or 0.5mm - I think vs 3. may have removed he nozzle size setting completely (which fries my brain a bit). Anyway I went back to 15.4.6 for most of my testing because you can set 0.45mm in the old Cura., Where I could get the same level of accuracy with the new Cura I know not. I know that to a certain extent you can increase/decrease the line width and get accuracy but whether that extends to a deviation of +/- 0.05mm again I know not. Hi @LaserBrain in terms of accuracy the two thinks that immediately come to mind are firstly checking that your belts are not loose and secondly recalibrating your stepper motors. Now you have a brand new printer which I assume has a standard steps/mm setting which UM will have tested, probably extensively; I have no idea if they test each new machine and recalibrate that setting if required. You might like to ask them and indeed what tolerance they expect on the X/Y accuracy. Personally, with the right settings, I would expect you to be able to get down to 50 microns variation as a an absolute minimum. Sorry just to stress, with a brand new machine I would not want to suggest that you start playing with the stepper calibration without having a word with UM first.

The vertical gradient is around 10c too I guess that depends on how thick your glass is.

Several options here to get faster. Walls: Go to custom menu and up near the top, in the Shell section, set wall line count to 3 giving you your 1.2. Now at the bottom you are 2.4. I think if you set your wall line count to 6 it will be OK at the top. Test it by sinking your model substantially into the build plate – change z location from 0 to –n. Print speed: It looks like you have a good surface there but with 200+ you might want to try and push that speed up a bit; see how faster (if at all ) you can go and still retain the quality. Print multiple models: No idea what experience you have with this but it will be faster in terms of throughput, less cooling down of the bed and reheating. If you are one of the many who print a single model at a time in the centre of the bed then this will test the accuracy of your bed levelling! You need to decide between “Print one at a time” and “Print all at once”. For this sort of quantity I always use “Print one at a time”. Pros: if you have 5 models and the printer fails 80% of the way through, 5-6 hours for you, then with “ print all at once” you have lost 5 models, with Print one at a time” you will completed 4 models; the extruder is not jumping between models all the time so there is much less change of stringing or artefacts being created on the surface. Cons: with “print all at once” you are likely to get more models on the plate. Mind you I use 15.04 for multiple model printing because it works well in 15.04 but seems to have gone awol in vs2 onwards. If you are a centre of the bed printer then do not forget that the peripheral areas of the bed take a lot longer to get up to desired temp. (20 minutes plus probably, obviously varies with printer model). When my multi print is finished I remove the glass plate and place on a glass table and immediately push the bed temp up to 80-90 so it is nice and hot to reheat the cool plate. Infill: If the 6 wall approach does not work then you will have infill in the lower reaches. In Cura set infill to 100% and see if that reduces print time. Weird though it may sound I have experienced this happening but of course it is entirely dependent on the model and your settings.

Lol you are better men than I; I have been using hairspray on glass for the past 4 years plus to ensure adhesion.

I assume that when you say make the cylinder larger you are increasing the diameter, not just the height, yes? If so then I agree with @SandervG it is likely cooling but without settings or pics it is just a wild guess. You want your layer print time to be say at least 10secs if reducing your extruder heat does not work. If need be print 2 or more copies to achieve this (all at once mode). It may be that you are going too fast with a small diameter, although you say you have reduced the speed - from what to what?

Nice one @ahoeben. I do not really know how the interaction works - do these settings override my firmware settings (Repetier Host), or does the firmware override the Cura settings? I had always assumed the latter.

Thanks for that @ghostkeeper, again really useful information.

Thank you @ghostkeeper, that was really helpful and interesting. May I ask a question/make an observation just to ensure I am understanding this correctly. If one specifies a line width of 0.5 then Cura will calculate the volume of filament to be extruded, per second or whatever, to create a .5mm line over the given distance in the time allotted from the print speed. I assume that the printer calculates the speed that the filament drive wheel has to turn to meet the requirements in the gcode. So, up to and only up to a point, the size of the nozzle is not too important; there will be less pressure with a .55 nozzle because the filament just flows through the nozzle to create a .5mm line and more pressure with a .45 nozzle because the filament needs to be forced through the small orifice fast enough to create a 5mm line. Once one goes beyond that point one will end up with a line that is not 5mm wide and/or failure because the printer drive system cannot cope with the pressure it imposes. Hopefully that is broadly right. One aspect that still eludes me in terms of where it fits in, is that my printer, driven by Repetier Hoist, knows what size nozzle it has (I assume!) because that is defined in the Repetier Host printer settings. I am not understanding what the printer end does with this knowledge, perhaps nothing?

Yup I had not really thought that one through, you could well be right. It could be done by the printer firmware. In fact, thinking about it, maybe nothing actually calculates the pressure as such. Cura says go from A to B at this speed and extrude this amount of filament; and presumably the printer via the firmware pushes the filament at the speed needed into the nozzle to achieve the Cura instruction. It is that speed or variation of it that causes the pressure and pressure variations. (thinking out aloud) What was confusing me I think is what I have never understood and that is how can a nozzle which has a 0.4 nozzle (in reality, not specification) push out anything other than a line that is 0.4mm wide - and yet people set line width either side of the spec. Cura always used to need nozzle diameter and line width which always made me think that the nozzle width came into the calculations somewhere

Hi @Jakeddesign, sorry for long delay, a variety of other things took my time away. I have pretty much completed my testing and my conclusions are... Line width: Nozzle; well Cura does not help here as it is no longer possible to enter the nozzle width. I do not know how Cura can calculate accurately the needed pressure if you tell it what line width you want but it does not know what filament width is being extruded. Maybe something for you to consider @SandervG My .4 nozzle extrudes .45 width filament so I tried both. What I found was that whilst they were both very similar in accuracy the 0.45 line width, i.e. reality, was more consistent. E.G taking two measurements from a block I found that the 0.45 Sample showed -0.01mm and -0.03mm accuracy (bearing in mind digital callipers only claim 0.02mm accuracy, the 0.04mm sample showed –0.03mm and + 0.05mm accuracy (so the range of error was considerably larger). This was substantially consistent across a range of measurements. Number of walls: I tried 1,2 & 4 walls. I did not see any real difference. The 2 & 4 walls had errors ranging from +0.02mm to +0.04mm, whilst the 1 wall showed a range 0.00mm to -0.04mm Layer height: Surprisingly (to me) printing at .100 layers was less accurate than printing at .300 layers (everything else - settings, cool down process and ambient temp. were the same). Not much testing done on this so I intend to revisit. Inside vs outside wall first: I did not do much testing on this but what I did do suggested that really there was no difference. Another one I will revisit once I have the stepper motors calibrated exactly; in between each set of tests I made minor changes to the steps per mm to hone it in to as close to zero error as possible. Settings etc. All test were done with print speeds all consistent at 30mm/s with the extruder set at 200 for .300 layers and 190 for .100 layers; 15% infill overlap and ambient temp. of around 24.6c.

Yup that is why I never measure at the bottom ?. With a piece that small you will be able to increase the nozzle to bed distance (reducing the pressure) and probably almost get rid of it and still retain bed adhesion.