I have yet to create a decent print.

[zews 1]

Moderator, there are a lot of blue lines in the area of the hollow section of the part. Instead of uploading a few screen shots as you requested, I made a movie of going through the layers of the part. As you can see, there are also blue lines in the areas where I have indicated there is "stringing" inside the infill (previous post). I wonder if it is all related, and if this is indeed a slicing issue.

I have a feeling that if it is indeed a slicing issue, there is nothing I can do about it.

 

Strangely, when playing back the movie, the frame is trimmed in the browser, but it can be viewed full screen.

 

[gr5 2,173]

That's a very very good bottom layer. I think you can do better. I don't think I've done better - well actuall I know I have in special case (call me gr5, not "moderator". There are other moderators).

First of all to get leveling better you can't do it with leveling procedure - you have to do it by printing bottom layer and then adjusting screws. However you might already have it perfect. Anyway the trick to getting the bottom even better is to print it thinner. By default the bottom layer is .3mm because that makes it easier to get the bottom really good. But if you want to eliminate the lines even more then make the bottom layer .1mm. But now the leveling will have to be even better. While the printer is printing the skirt consider adjusting the 3 screws a little bit - I think you want it slightly closer. Alternatively you can adjust the flow. Maybe set it to 110% for the fist layer and then back to 100% some time during second layer.

 

[gr5 2,173]

Regarding the internal stringing - that's normal. And from the video I can see that many of the travel moves are right towards the spot where you are underextruding. You can reduce this by keeping the travel speed fast (it's at 150mm/sec right now - you can safely go even faster to 200mm/sec) but more importantly print slower and colder. This way the nozzle will leak less during the travel moves so that there will still be plenty of plastic in the nozzle for the outer shell.

Try 25mm/sec print speed and 190C temperature. I'm not sure that will work but I think it will. That's what I would do to try to get rid of those underextrusion holes in the side related to non-extruding moves.

 

[zews 1]

gr5, thank you for your continued support regarding my trials in getting better prints. I hope other beginners will also benefit from your guidance.

I will give your suggestions a try. Regarding "make the bottom layer .1mm" I have another question.

As you can see in the images of my Cura setup, in the Basic tab under Fill, I have .8 mm for Bottom/Top thickness, and in the Advanced tab under Quality I have .15 mm for Initial layer thickness. Isn't this what you are talking about? The way I understand this, is that my initial (bottom) layer is .15 mm, and the total thickness of the bottom shell is .8 mm. You want me to change the .15mm to .1mm, even though it is already half of the default of .3 mm.

I don't quite understand that I can't get the leveling right by following the procedure, and that I now have to adjust the nuts "While the printer is printing the skirt ... " In this case I assume I will indeed have to turn the nuts counter clockwise to bring the build plate closer to the nozzle. But if I do this arbitrarily "adjusting the 3 screws a little bit" would I not risk to be off level again? I don't get how to do this accurately and predictably. What do you think about my idea to do the leveling with a metal feeler gauge instead of paper. I can use a feeler gauge that is thinner than paper, and steel does not compress like paper can. Is it possible that the fact that paper can compress when it is pushed in between the build plate and the nozzle during the leveling procedure, could mean that the level can be off a little.

How do I adjust the flow during printing?

What do you think might be the cause of the moire patterns on the sides?

 

[illuminarti 18]

You can adjust the flow during printing using the Tune menu.

I'd be inclined to go with a thicker first layer, so there is more material being extruded. Make sure that you have installed the firmware from Cura 14.07 (in addition to using that version for slicing).

Try turning off 'enable combing' in the advanced settings. That will eliminate the stringing on the infill, and probably help with the thin patches in the walls.

 

[illuminarti 18]

Also, I recommend that you just level it by eye - looking along the surface of the glass until you see the nozzle just touching its reflection in the glass. That's fractionally too close, but it's a lot quicker, and combined with a thick (0.3mm) first layer, it should help to eliminate any visible lines on the first layer.

Also - you mentioned about the overall height of the bed... start by looking through the gap, and adjust the height of the back screw until the terminal block is almost touching the lower plate - about a 1mm gap between terminal block and lower plate is fine. Tighten the two front screws by about the same amount (so the bed stays about level overall), and then rerun the leveling process, to level it to the new spring height.

 

[gr5 2,173]

I think the leveling procedure, with practice can get the bed level to about .03mm but you are demanding higher quality on the first layer than anyone I have seen before. I have only gotten that kind of quality once - when I was making an airplane (that actually flies). On that part I did .1mm bottom layer and there are no seams at all.

So I recommend you stop using the normal leveling procedure. I haven't leveled in over a month because once you get it right it tends to stay perfect for a long time.

Also leveling will change when you heat the bed and nozzle because heat causes things to expand and changes the level point.

So why not print just the skirt only and adjust while printing the skirt? You can print it very slow and cancel the print once the skirt finishes and repeat until you get it perfect. You want the second pass of the skirt to just barely touch the first pass of the skirt when you peel it up and look at the underside - you want all gaps/cracks to be invisible/gone.

This method is more accurate than the normal procedure and you should be able to get it down to about .01mm (10X thinner than a .1mm layer of filament). Especially if you only care about the very center of your print area because you are printing a small knob.

 

You want me to change the .15mm to .1mm, even though it is already half of the default of .3 mm.

 

Yes, that's what I meant. Or alternatively you could just move the glass a little closer. As long as you have gaps between the lines (as I saw in your photo) you can only remove those by getting the nozzle and glass a wee bit closer.

 

[gr5 2,173]

The moire pattern is bizarre. I'd have to see the STL file. Maybe that "flat" side isn't made up of 2 triangles but instead thousands?

 

[zews 1]

gr5,

I'd like to send you the STL file so you can have a look at it. What is the best way to do this. Can I somehow upload it to the forum, or should I put it in my Dropbox?

I wonder if my conversion from a NURBS model in Rhino to a polygon mesh for export to STL might have been the culprit. Maybe I created the mesh with too many polygons, which would be appropriate for HiDef printing by a commercial printing bureau, but is way too many than any FFF printer can handle anyway.

Either way, I'd love to get that file to you in the hope that looking at that might give you some insight into those weird moire patterns.

 

[gr5 2,173]

Dropbox is good - you can put it in the public folder and send me a link for example.

If it has tons of polygons you can reduce them with meshlab - here's instructions (meshlabis free):

http://www.shapeways.com/tutorials/polygon_reduction_with_meshlab

 

 

[zews 1]

gr5,

I have put the stl file in my dropbox. The link is https://dl.dropboxusercontent.com/u/66542951/Lathe%20power%20knob%2002.stl

If too many polygons is the cause of the moire patterns, I could create a mesh with fewer polygons in Rhino. I don't think I would need Meshlab for that.

 

[LePaul 321]

GR5 is a great guy, he's helped me along when I first put my Ultimaker (original) together

Hang in there, as you have seen, 3D printing isn't plug n play...it seems every print requires some strategy!

 

[gr5 2,173]

Holy crap! That simple knob has 88,000 polygons! I think you can get it down to a few hundred. The printer is trying to print all 88,000 polygons. That's where the moire pattern comes from.

Meshlab is extremely smart about reducing polygons. If two polygons are *almost* on the same plane (say .000003 degrees different) then it is more likely to combine those 2 polygons into 1 versus two polygons near a corner.

Or you can try using rhino to do this.

Try to get the number of line segments on a corner to be maybe 6 at the most. You have about 40.

More than 10 and Marlin can't handle it very well and slows down on each corner causing overextrusion and a bad look to the part. Marlin can only look ahead about 10 line segments and has to be ready to stop so it starts slowing down 10 segments ahead if they are close together. You have 40 line segments in 1mm. That's just too much for Marlin's tiny little computer to handle.

 

[gr5 2,173]

I managed to make a similar pattern in sketchup which shows all the polygons:

 

 

[pm_dude 27]

More than 10 and Marlin can't handle it very well and slows down on each corner causing overextrusion and a bad look to the part. Marlin can only look ahead about 10 line segments and has to be ready to stop so it starts slowing down 10 segments ahead if they are close together. You have 40 line segments in 1mm. That's just too much for Marlin's tiny little computer to handle.

 

Very interesting point gr5. Additionally it will greatly increase slicing time in Cura too. Reminds me of that model coming from ZBrush with 40M polys.

 

[zews 1]

Well, things have gotten from bad to worse, much worse.

After updating to the latest Cura update and updating the printer firmware, I tried to print the part again, without having changed any print settings. The first layer printed much worse than when I last printed the part, which I posted on July 19 at 2:08 PM with a photo. The layer again printed with a lot of under extrusion. I can upload a photo, but that does not help much. I then adjusted the screws as had been suggested. This resulted in a slightly better print, but still with a lot of under extrusion.

I then thought that it might be time to reset the printer to factory setting because of the new firmware, so I did the whole leveling procedure again. By now I have done that a couple of dozen times. Now this is the result of printing the first layer. I have had this printer several months now, and I have still not been able to get a decent print. I am beginning to think that it may not be me.

 

 

BTW, I found what seems to be at the very least a typo in the new version of Cura. In the Advanced tab in the setting panel under Quality it says "Initial layer line with (%)". I think that should say "Initial layer line width (%)" BTW, I had it set to 120% to make sure I would not have under extrusion again. As you can see from the photo, that did not work. Print speed was set to 20 mm/s. It seems that there is not even any filament coming out of the nozzle.

When I go to Maintenance/Advanced/Move material and I wait until the nozzle has reached a temperature or 210 and I then follow the instruction "Rotate to extrude", nothing happens. I can feel the wheel on the back of the printer rotating, but the filament does not advance.

In the Basic tab, I do not understand the field Bottom/Top thickness (mm). In the explanation when mousing over the field for this it says "This controls the thickness of the bottom and top layers, the amount of solid layers put down is calculated by the layer thickness and this value. Having this value a multiple of the layer thickness makes sense. And keep it near your wall thickness to make an evenly strong part."

This makes no sense to me at all. It seems that whoever wrote this uses layer thickness and layer height interchangeably.

I wish there was a truly beginners guide for Cura as well as for this printer. I did not expect this to be easy, but this is ridiculous. I have mastered 3D modeling and rendering which I have been doing for 17 years, I expected this to be a lot easier than that.

 

[zews 1]

In the Cura settings, how do Basic/Fill/Bottom/Top thickness (mm) and Advanced/Quality/Initial layer thickness (mm) relate to each other.

Are these the same or different settings? They seem to be addressing the same setting, since when you mouse over Advanced/Quality/Initial layer thickness it says "Layer thickness of the bottom layer". If they are indeed addressing the same issue (layer) why does this need to be set in the Basic as well as the Advanced tab? If they are different, what is the difference?

Under Basic/Fill/Bottom/Top thickness (mm) I keep re-reading "This controls the thickness of the bottom and top layers, the amount of solid layers put down is calculated by the layer thickness and this value. Having this value a multiple of the layer thickness makes sense. And keep it near your wall thickness to make an evenly strong part." over and over again.

This statement makes no sense to me at all. It sounds like whoever wrote this uses "Layer height", and "Bottom/Top thickness interchangeably, and it still makes no sense to me. Can somebody please explain this.

 

[zews 1]

Last night I was finally able to start a print with a good bottom layer. However, after just a few layers the infill started to print. This photo was shot from the bottom. As you can see, the bottom layer is so paper thin, that light shines through.

 

 

So this made me think that I was beginning to understand the meaning of the Cura setting Basic/Fill/Bottom/Top thickness (mm). This morning I increased the setting to increase the thickness of the bottom layer and started another print. I had made no changes at all to any other setting in Cura or any settings on the printer. I had not touched the printer at all. This was the result of the print:

 

 

It seems that there is something wrong again with leveling as well as with filament feeding.

I do not understand why the leveling is off, after I had just made a print last night where the leveling was correct. Why would leveling change overnight? And why would the filament suddenly not feed either.

I went back to Maintenance/Advanced/Move material. Again the filament would not move when I rotated the knob after the nozzle had reached 210 degrees. Again the extruder wheel would rotate, but the filament did not move. I had to rather forcefully push the filament from the back into the extruder to make it move. This can't possibly the way this is intended to work.

 

[zews 1]

I am printing the same part again at the moment, and I am beginning to hope that I may be on the road to success. This is the first layer printing.

 

 

It seems that I still have a leveling problem, but if you look closely at the first image I posted earlier today, you will see that the right side of the print is darker, i.e. thicker. So the leveling at that point was probably also not perfect. I am beginning to think, that because my "Initial layer thickness" is set to 0.1 mm leveling precision becomes much more crucial. But since that bottom layer was in fact very good I assume I can leave the leveling alone.

I also turned "Enable combing" off as illuminarti suggested, and this has indeed eliminated the stringing in the infill.

 

Since I also followed the suggestion to print slower I am now printing at 20 mm/sec. I still have about 4 hours to go to complete the print. I will report the result.

 

[gr5 2,173]

I am beginning to think, that because my "Initial layer thickness" is set to 0.1 mm leveling precision becomes much more crucial.

 

Yes! You got that right. That is why the default is .3mm for the bottom layer. This means you can be 3X as inaccurate.

If you print a perfect cube, the walls of that cube are infinitely thin in CAD. Or another way to look at it, the cube is solid in cad.

But that's a waste of PLA to print solid. So you choose the "shell" thickness and "top/bottom" thickness for your final cube. That's the thickness of the walls before you hit the "infill".

The slicer slices the 3D object into 2D layers and many of the settings are with reference to 2D layers but some are reference to 3D model. The "shell" and "infill" settings are related to a given slice. If your shell is .8mm and nozzle diameter is .4mm you get 2 "shell" passes and the rest of the interior is filled with "infill".

Layer height and "initial" layer height is how far to move the Z axis between layers. The first layer should be .3 for beginners. I rarely go thinner than .3 but for some special case parts I do. This are slice centric terms.

Bottom/top layer thickness - go back to that perfect cube - this sets how thick the top and bottom of the cube is printed before you come to infill. It needs to be a multiple of the "layer height" parameter because the Z axis will only move in steps of layer height. If bottom/top layer thickness equals shell thickness then your cube will be symmetrically thick on all 6 sides.

bottom/top layer thickness is more complicated for other shapes.

 

[gr5 2,173]

There is something wrong - there's absolutely no reason to start a print if move filament isn't working. Try backing the filament up until you see it moving up in the bowden and going back down - sometimes it catches. Or you may have ground the filament down inside the feeder. You could try turning the knob (move filament) with one hand and pushing up on the filament in the back of the machine with the other to give the feeder help until it gets past a bad spot. I've only had this happen once or twice and indicates you are doing something else wrong (maybe spring is too weak or too strong in the feeder but don't worry about it until you can consistently get it to be a problem).

Also going over 100% for line width or flow is counter intuitive. It is more likely to build up too much pressure in the nozzle and have the feeder skip backwards resulting in underextrusion. Best to keep those at 100%.

 

[gr5 2,173]

Cura manual is here:

https://www.ultimaker.com/spree/uploads/38/original/Cura_User-Manual_v1.0.pdf

 

[zews 1]

The print I am doing right now does not seem to have the issue on the side with the under extrusion mirroring the square hole inside the part, ... yet.

But I still have the moire pattern even though I have exported a mesh from Rhino with much fewer polygons. So I downloaded and installed Meshlab, and now I have a new set of issues.

When I go to Filters/Remeshing, Simplification and Reconstruction there are about 40 options to choose from. Since I really have no clue which one to pick I picked a few that made the most sense. The program crashes each time no matter which option I choose.

 

[zews 1]

gr5,

I have created yet another mesh with much fewer polygons. Meshlab tells me it has 3,106 faces. I have uploaded it to my dropbox at https://dl.dropboxusercontent.com/u/66542951/Lathe%20power%20knob%2005.stl

When I open this file in Cura the entire surface of the part does not look very smooth at all as my NURBS model does. If I save it with even fewer polygons it only gets worse.

Is it safe to assume that if the model does not look smooth in Cura, it will not print smooth either?

 

[illuminarti 18]

It sounds like you are grinding away the filament in the feeder - that's why it's not feeding properly at the start, and the motor is turning, but the filament isn't moving. If that happens, you need to stop, remove the filament, and cut off the damaged part. Pushing damaged filament into the Bowden tube is only going to make things worse.

What firmware info does Maintenance -> Advanced -> Version give you?