yellowshark

Ah now that I did not know, as a 15.4 user. But is that a z scar? I can see overlaps where the scar appears on the same layers at different corners. I am wondering whether it is caused by the deceleration and acceleration coupled with too high a temp. As I said earlier I think .200 at 20s is too hot at 20mm/s or 30mm/s. I am still trying to get my head around why the top of the model looks perfect, compared with the earlier layers, but where the layer print times will be a lot lower. o I am not convincedhave not seen anything said in the thread about retraction and print head movement. Also, to me it does not explain the partial presence of the scar and the scar occurs in more than one place.

Good point, it is fairly normal not to have to sign in just to view a forum

Hi I had assumed it was a single print but looking at it again I am wondering if you are printing more than copy? The apex area say top 1/4 of the print has come out very well, which given the small layer area at the top is maybe a bit surprising for a single copy. Trying to get my head around it versus the lower part of the model

Way too hot. You probably should be using less than 190c with 20mm/s and 0.05 layer, assuming you have no blockages or feed system problems - which should be fixed anyway rather than pushing up the temp.

Opposite for me; now I keep getting signed out (it is intermittent). before I could leave a page displaying, oh for ever really. Now if I leave it, oh say for an a couple of hours, when I come back I have to sign in again. Windows 7 SP1 & IE 11

Yup I probably strongly agree with @gr5 which is why I asked my last question to ascertain what was happening at the bottom, which will also be running at 50. The only thing that confuses me is that it looks so regular/neat which is something I have not seen before with under-extrusion.

Ok, you said the first layer was fine, did you watch layers 2,3,4,5, were they OK?

Erik I have had success in the past by removing the nozzle and indeed the extruder and placing it/them in a pan of boiling water for several minutes. I then use a BBQ thingly (grip) to extract the piece and hold the bore up to a light and use an implement to scrape/push pieces away/out from/of the bore.

Can you go to the Cura menu and select the Expert tab and Open Expert settings. Under Infill have you got Solid Infill Top and Solid Infill Bottom both ticked?

In general it comes a couple of lines later M117 Printing... ;Layer count: 134 ;LAYER:0 M107 G0 F9000 X122.200 Y112.200 Z0.100 ie the layer is 0.100 - oop sorry the last line is positioning the z-axis relative to its last position, which as this is the 1st layer will be 0 - which means the layer height for this layer is .1

Hey it is great that you have a positive/constructive view on it - it is always tricky if you want to "challenge" something. I did not know how the levelling worked either when I was a newbie a couple of years ago but kindly illuminarti and gr5 explained it to me. Quote by JATMN Thanks for giving an actual response and not just blasting me. lol Not had my UM2 but a couple of months and getting use to this firmware Quote by yellowshark ... Not complete convinced of this but ok.. because at .3 and .2 my printer is starting at the same level from the glass as it was when I leveled at.. This is evident because at .3 it is massively over extruding so much that it causes the extruder to skip and the 2nd layer the nozzle is grinding across the surface of the first layer. Lol I am almost bound to say It can’t be!!. Are you able to look at your gcode. I have just copied this, Firstly with 1st layer set to .300 ;Layer count: 132 ;LAYER:0 M107 G0 F9000 X122.200 Y112.200 Z0.300 ;TYPE:SKIRT G1 F1200 X157.800 Y112.200 E0.66966 G1 X157.800 Y147.800 E1.33931 G1 X122.200 Y147.800 E2.00897 and with 1st layer set to .100 ;Layer count: 134 ;LAYER:0 M107 G0 F9000 X122.200 Y112.200 Z0.100 ;TYPE:SKIRT G1 F1200 X157.800 Y112.200 E0.22322 G1 X157.800 Y147.800 E0.44644 G1 X122.200 Y147.800 E0.66966 Look, when Cura creates the gcode (or maybe it is done by the firmware, I have no idea on that one)( @SandervG ?) it has to, and it does, set the z-axis position for the layer to be printed – it does this for every layer. I think what you have done is that when levelling you have either used a piece of paper that is thinner than 0.1mm or you have done your setup with too much friction present. Both will leave the nozzle to close to the print bed. In your case too close so that a layer of.0.300 just does not have enough room but a layer of 0.200 does have enough room. Do your levelling again and it will resolve itself. Totally where I was going with this.. which I guess while not true with the UM2 and Cura.. it is however completely accurate with my Duplicator 4 (sailfish firmware) and S3D.. .050 prints I have done lots of on that printer.  My first thought is that this would be consistent across all slicers. Let us see what my test results are. I understand your infill vs wall speed part.. but as for my reasoning for faster print speed for over extrusion.. I have tested this part extensively.. I had a VERY noticeable difference in my first layer with running at about double first layer speed than what was default while at .2 first layer height. Hmn what do I say? What I will say is that generally the slower you print the better the quality you will have – I am referring to the entire model, not just the first layer. If you have a small intricate model then if you go too slow (for it) the nozzle can overheat the plastic causing melting and a poor finish. But the general rule is correct. 9 times out of 10 20mm/s will be better than 30mm/s. Buy hey if doubling the 1st layer speed works for you then good on you

Well that's Brits for you; rumour has that the UK user group is going to block the channel tunnel with printers if Europe implements border controls

Lol when we are playing baseball sometimes the guys use the printer to stand on when pitching and I guess I ought to re-level after that but I don't.

Hi @JATMN , or was that BATMN, sorry. Thanks for taking the time to reply, appreciated. Well firstly your 2nd para is, as I understand it, wrong, or I am misunderstanding what you are saying, you did not type what you were thinking, or I am wrong. If you are using the bed levelling wizard then the firmware assumes that you have then set the bed at the z=0.1mm height (width of paper) and calibrates itself accordingly so that its z=0 position has the bed 0.1mm closer to the nozzle - i.e., just touching it. Before printing the 1st line of layer 0 (ie Cura’s "1st layer” ) the gcode sets the z position to the measurement of your “1st layer thickness”, in your example .300. So the gap that you have to extrude your 1st layer into is 0.300, not 0.12, or to be absolutely accurate in your example, 0.320. I would add that if UM have now issued a card that measures 0.12 I assume they have changed the firmware accordingly. Not that material really; if I change the z-offset by 0.04 I can always see a change in quality of 1st layer but if I change it by 0.02 I cannot see a difference; sometimes I think I do but it is so marginal that the reality means it really makes no difference. I make my changes in the gcode rather than twiddling the knobs so I know my stated figures are accurate. If you choose a 1st layer height of 0.1mm then gap you have for printing that is 0.1mm. In essence therefore I think what you are saying in paragraph3 is not valid. Also as I have just said a change of 0.02 in the gap will have no noticeable difference on a layer height of 0.300. I know, I have been there, done it. If I have to re-level the bed, e.g. nozzle change, I will always go that final 0.02 change and it never makes a difference. NOW perhaps what you are saying, except you did not, is that the thinner the 1st layer used the closer the bed needs to be to the nozzle to improve adhesion. Whether or not that is true, I have no idea. But I am going to test that today and report back  Also you said in para. 4 “with a faster print speed to prevent too much over extrusion”. I am not convinced on this. Changing the speed over a given distance does not change the volume of filament extruded – check your gcode; it just means your printer has to extrude the filament faster – which is why, unless there is a good reason, it is always better to use the same speed for every movement on a given layer, i.e. do not run you wall speed at 40 and you infill at 80 - and yes sometimes there are reasons, if you can get away with it.

Sorry but if you get your levelling right there should be no need to re-level for months and months, unless you change the nozzle which may change the z-offset distance, or possibly use a non-normal PLA which has different flow characteristics (that is a guess).

Ok then if you are at 20/30mm/s then with .200 you can probably go down to 190c, especially if your drive/feed system is 100%. I would certainly push it down until you see under-extrusion. Also make sure your wall and infill speeds are all the same. If you can make your .stl available I do not mind having a try with it.

You do not tell us you print speed which is rather important. Can we assume you fans are 100%? As @neotko said cool and slow will probably go a long way for you depending on current settings.

Using a brim will also help if you have problems again

Hi @thinusp the other thing to realise when you have differing speeds across the layer, is that every time you change the speed you change the pressure in the extruder and this takes a bit of time to stabilise and as a result can deposit artefacts on the surface which is another reason for sticking to one speed normally. Sure if have a large plinth under your model then printing the infill at 30mm/s is boring and can be case for pushing up the infill speed. If that is going to cause problems with the actual model then there are ways of modifying the speeds as you go along the z-axis.

hi dvdmcd, turning up the temp and particular flow will get you nowhere in reality. If you start going away from your normal setting you might get a better result but you are probably hiding a problem which will come back to bite you. You need post relative settings for questions like these otherwise we are guessing in the dark. Can you please tell us. Layer thickness; print speed; infill %; infill print speed;extruder temp; bottom/top thickness; top/bottom speed(0.0?). Also you commented that 1st layer was fine but are you saying that 2nd layer was not good, and all the layers after that? Have you printed that particular piece successfully previously? Is the height of the walls around the circle in the middle the same height of the perimeter walls of the entire piece? Neither of those walls seem to be under-extruded to me, but without settings info it is difficult to draw conclusions. Also difficult from that photo to fully understand but is the vertical wall running around the outside OK ? it looks bit dodgy to me from that angle, which is almost invisible

OK if you using 20% infill then yes your original settings were no thick enough. When you say you increased the top did you use 1.2mm as suggested? May I suggest that you run at 1.2mm again but use 40% infill. If that makes no difference then I am guessing your problem lays elsewhere. With 40% infill, which is what I use mostly, 6 layers of .200 will cover it.

I find the quick settings for .4 nozzle really strange. I would go under 210c for all three of them and probably go 185c for the Normal. Do not usually go to .05 layers but I suspect I would do hi below 185

Not needed for Cola, that does not get stuck coming out of the bottle

Lol you do not need paper or card, just change the z offset in cura start gcode and set to any measurement you want

I only recalibrate if I change the nozzle; no guarantee that the distance has not changed. I did once try measuring the distance from the extruder edge but I was not happy I was getting it accurate.