yellowshark

As an aside, although germane, is it possible to over-cool PLA (assuming ambient temp. is OK)? I have always thought the recommended fan setting is 100%, once you have printed the first few layers.

Hi I suspect 4 top layers is a problem, that is only a depth of 0.8mm, I tend to aim for 0.9 to 1.2. And your infill % of course will impact this - the denser the infill the quicker you will close the surface.

Lol, yes and don't know. The process you use for calibrating the extrusion length is pretty much the same as me except that I look for tighter tolerance, say 50 microns not <1000. When I start the calibration I do not extrude filament, I measure the movement of the nozzle and once I think the calibration is good I validate/fine tune the calibration by printing and measuring filament. Wall thickness and over extrusion. Not a simple subject but my view is that you are probably not over-extruding and my suspicion is that you nozzle diameter is 0.44 and therefore your Cura settings are wrong and line width and nozzle should be set to 0.44. I may be wrong but all I can say is that I had exactly the same thing a couple of years ago and corrected my Cura settings to 0.45 and saw improvement in my surface quality. It is probably worth pondering on this and trying some tests. Somebody, I think @geert_2, machined himself a probe with increasing diameter so that he can measure the internal diameter of his nozzle.

The top surface is probably pillowing, i.e. you are not printing enough layers to close out the surface. Also/alternatively your fans are not running at 100% - I am assuming you are using PLA. With 0.3 layer height you will need at least 3 top layers, personally I would use 4 minimum to get the job done. You can always dial it back if you watch the print and see how many layers you do need. Generally speaking the thinner the layers the more top layers you need. So with 0.15 layers you will need at least 6 top layers but probably 8. Then in addition with the thinner layer you may need another 2 or 3. As before specify enough. Watch how many you do need and dial back if required. The bottom layer. I suspect this is over-extrusion and/or the nozzle being very close to the bed; nothing wrong in that but you need to compensate. I always run my nozzle/bed distance very tight and print the 1st layer at 70% flow to compensate

Err yes it does! If you change from a 0.4 to 0.8 nozzle you will change your line width which will increase the volume of extrusion per sec. That is why you uses a larger nozzle, predominantly to reduce print time.

Sorry I still do not understand, or rather I disagree. A 0.4 rectangle has a greater surface area than a 0.4 circle. Therefore if the calculation is based on a rectangular profile Cura will set the pressure/feed speed to deliver X amount of material per sec. If the calculation is based on a circular profile I would expect Cura to deliver Y amount of material where Y is less than X. So in your scenario Cura is delivering too much material. That would suggest that either you end up with over-extrusion or a nozzle blockage. I am no expert, I never studied fluid mechanics, but I do know that the filament that extrudes from my nozzle is circular not rectangular. So why do the Cura programmers do their calcs on a rectangular profile which does not exist? I am happy to be told I am wrong, lol if it is explained, but right now it does not seem logical to me.

Never heard of anyone using a layer height a thick as 0.8, I cannot help thinking that this is one element that is probably causing a problem, but that is a guess, I have never gone anywhere near 0.8 Agree with @geert_2 on the cooling side. As a guideline I use 10 secs as my minimum layer time, with 100% fan, again I am guessing but with 0.8 layers you may need more than 10 secs. Also I would experiment with the extruder temp. Try 210 and 220 and gradually find the best temp; e.g. if 210 is better than 215 then try 205. With a layer height of 0.8 I am sure any temp. suggestions from us will be guesses.

When you say the nozzle shape does not come into it could you expand on that a bit, it sure takes a lot more concrete to fill a rectangular column in a building than it does a circular column. I would have thought nozzle shape should come into it.

Funny how we all do different things to get the same result. When you say "...if a filament always over-extrudes" I would say it does not, you always have the wrong settings. Get the settings correct and you do not have to muck around with flow%. I guess we come at this from different perspectives and probably nothing wrong in that. I use 70% flow for 1st layer, along with standard print temp (i.e. I do not set a different 1st layer temp) as on my printer flow % changes and stabilises a lot faster than a temp. change. And for everything else on all filaments/colours etc. I use 100% flow. I control my extrusion, i.e. no under-extrusion and no over-extrusion, with the temperature.

I am no expert on this but with a circular nozzle would Cura assume the cross section is rectangular?

It amazes me that people still do not get this. Maybe it should be the opening banner on Cura so that newbies are aware. Something I tried fairly recently and is now standard for me, was to reduce the Cura standard print acceleration by 50%. It did not have any real impact on the print time although may partially be due to the geometry, so it is not a guarantee!

Hi @Timbe good to hear you have a satisfactory result. I guess you are using the latest version, or close to, of Cura. I must install ia later version and give it a try again !

If you try using the ironing function you may find that will improve the top surface for you. I have only tried it once and in parts of the model it was gobsmackingly good but in other parts it was poor. But I was using Cura 2.7 and I suspect it has been improved in later versions

Well I suppose everything you say, under certain circumstances, is correct. BUT if your printer is setup correctly and your slicer settings are correct/optimum, then you are wrong. Under these circumstances if your nozzle is physically 0.4mm and you have specified line width as 0.4mm then that is what you will get; it does not matter what layer height or print speed you are using. If the line width were not 0.4 then you would not get a perfect finish and would probably get some minor dimensional errors. One caveat; the faster you go the less accurate you become and the lower quality you get. This is not something I have researched but I had always figured that was a mechanical issue. Somewhat like a car going around corner, the faster you go the more understeer you get, assuming the car has been setup to understeer which is the case with all family/saloon cars etc.

That is why is it always best to set all your print speeds to the same value. There will be exceptions, I am thinking of a flat surface which covers most of the print bed and you certainly are unlikely to want to run the infill at 20 mm/s ! With something that size as long as you print inner wall(s) first you should be fine; with something smaller, but still big enough to want a fast infill, then printing an extra wall may overcome the problem.

No I measured the filament flowing out, not the physical hole. I.e. I manually fed filament from the nozzle, using Repetier Host printer control software which provides the capability, cut the filament off and measured it with a digital calliper; which I did several times to check consistency.

My point is that the rated size of my nozzle is 0.4. So unsurprisingly in Cura I set my nozzle size to 0.4 and line width to 0.4. But at some stage, about a year ago, I checked this and found that my nozzle size was 0.45, wear and tear? Or to be more accurate the width of the filament flowing out of the nozzle with a manual feed was 0.45. So I set nozzle size and line width to 0.45 and improved my results

What has not been mentioned is setting your line width to what actually is extruded rather than the physical specification; i.e. what comes out of the nozzle not what gets squished onto the build plate. I have been running a nozzle and line width for some time now of 0.45 having checked this. Lol it works for me.

… and anyone who has to suffer the utterly effing mess of Windows Update under Windows 10 will know that not fixing something that aint broke is the way to a stress free life !!!!!

Yup to put that in real life rather than from the software laboratory. The user control has to be failsafe. We have Cura on two laptops, one being a play around/test laptop and the other being the print control laptop for production. We would certainly not want our production laptop automatically updated and bringing down a days production!!

Thanks @SmithyI am familiar with their on-demand service BUT I was not aware that it went down as low as 1 reel!😀I have just checked the RAL colour chart and their Pure White is what I need methinks. I shall get my order in and await the sample 😃

@geert_2 is right, on that geometry slow and cool is key. I wonder what your settings are?; personally I would go no faster than 30mm/s and 190-195 degrees depending on layer height. Now another thing that could help you... These two versions were printed with the same filament and settings except the first one used a 0.4 nozzle and the second one a 0.8 nozzle. I guess I may have pushed the extruder temp up 5 degrees for the extra flow of filament from the 8mm nozzle. I cannot guarantee it would work, your curve is convex and mine concave but the principle is the same, more material in the the wall being printed laying down on the previous layer. Err lol I was shocked too!

Hi @Smithy and @geert_2 most helpful, it is always good to get feedback from users. Lol I think I am in a bit of a rock and a hard place here. I use the Arctic white for modern and retro architecture. It s always difficult with colours on the web and colour calibration etc. but yes the Standard white does look a bit creamy. They also have a semi matt white but I cannot see any difference between the two, from the pics on the colorFabb site. Now the Blueish White is certainly different BUT could be an interesting replacement. I have a 3D shop about 40 mins drive away that stocks colorFabb so I think I need to take a trip there and try and see them in the flesh. It is good to hear that you find them pretty easy to use; yes I love Dutch orange, a reel of that and ironically Blue-grey arrived this morning. When I first started Dutch orange set the bar for me for quality of output; I have one, maybe two Faberdashery filaments that match it but I have never bettered it. I will let you know what I decide 🙂

Hi I had a similar problem last week. I was printing circular geometry, reasonably unusual for me. I fixed it by changing two settings - no stupidly I do not know whether they both contributed or just one of them! I will revisit that but I was in a rush at the time. I changed z-alignment from random (which I always use) to user specified and changed print acceleration from 3000 (default) to 1500.

Hmn, I have a specially manufactured PLA which has an anti-microbial additive mixed in, about 3% if I remember rightly, for use in the medical field, to prevent the transfer of microbes from one user to another. Of course they may not be but I suspect they will be similar. Anyway it did not impact my temperature to any great degree. I vaguely recall I may have changed the temp by 5 degrees but cannot remember whether that was + or - and I do not have the production notes on this laptop. At 30mm/s and 0.2 layer for normal PLA you should not really need more than 195, depending on how well your printer is setup. Adding another 35 degrees just seems too much to me but then smart arses have been known to be wrong! I suggest you print some 10mm cubes at various temps and see how it goes - lol I will be interested to hear what your results are