I have yet to create a decent print.

[zews 1]

illuminarti,

Version 14.07.0

The last print came out with a pretty decent and nowhere near perfect "initial layer thickness" of 0.1 mm. The rest of the printed part is just as bad as the first ones I posted. The same under extrusion on the sides where the internal hole is and the same moire pattern.

I will print my next attempt with a 0.3 mm initial layer and see what happens.

Because I am now mainly curious if a dramatically lower polygon count reduces or removes the moire pattern and under extrusion around the hole, I have reduced the count from over 88,000 to 3,100. I will also increase the layer height from .06 to .3 mm, and the printing speed from 20 to 50 mm/sec. That way I can see a result in about 30 minutes instead of well over 4 hours.

 

[gr5 2,167]

there are about 40 options to choose from

 

The meshlab article I sent you had suggestions for every setting in meshlab.

 

[gr5 2,167]

88,000 to 3,100

 

Can't you just look at it in Meshlab or some other cad program and see if it's going to have too many polygons. Certainly if it looks "low poly" to your eyes in cad it will print out low poly.

 

[gr5 2,167]

.06 to .3 mm, and the printing speed from 20 to 50 mm/sec

 

Um. So you are going to increase the printing volume from:

.06 * 20 * .4 = .48 mm^3/sec

to

.3 * 50 * .4 = 6 mm^3/sec

???

That sounds like a good opportunity for underextrusion. Well if you are going to print that fast (6mm^3/sec) I recommend 240C.

Or instead you could print .2mm layer height 35mm/sec and 230C and you should get beautiful results and not have to wait so long.

Or you can use the "cut off object bottom" feature in cura and just print the walls of the knob to test for the pattern.

 

[zews 1]

Things turned out much worse than expected. I will post photos tomorrow.

What surprised me more than anything else, is that event hough the initial layer was set to .3 mm instead of .1 mm as before, the bottom layer was full of under extrusions.

The previous bottom layer of .1 mm was of much better quality (almost perfect) than the .3 mm layer. gr5 suggested that this would not be the case.

I am now at my wit's end. This no longer makes sense at all.

 

[gr5 2,167]

When initial layer height is changed to .3 it changes TWO THINGS. It starts off at Z=0.3 (instead of Z=0.1) and it also extrudes 3X as much to fill in 3X as much space.

So you are asking the printer to print 3X as fast as you had been previously. Any time you speed up the volume of plastic by 3X you shouldn't be surprised if it underextrudes.

So you could either:

1) slow down the first layer using the TUNE feature to 30% and put it back at 100% after the first layer

2) Raise the temperature significantly (again - maybe you should check your print speed against this graph - remember - .3mm is 1.5X thicker than .2mm and this graph was done for .2mm so go 3X slower than dark blue line (2X for safety 1.5X because thicker):

http://umforum.ultimaker.com/index.php?/topic/4127-um2-extrusion-rates-revisited/

If you can't print at the speeds on the graph it could still be your leveling is off - only the first layer is affected by leveling anyway. You could test your printer to see if it is extruding fine. I suspect it is but there is a test here:

http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/

 

[zews 1]

gr5,

How about I try my lower polygon count print with the following setting:

Initial layer 0.3 mm

Print speed 20 mm/sec

What do you suggest I set the layer height at? I am mainly interested to see if I can get rid of the moire pattern.

As you can see in the photo, not only was I not able to get rid of the moire pattern in the lower polygon count model, but this print now also introduced 7 vertical lines that are also present in the mesh. I did not have these lines previously.

 

 

 

Previously printed part with .1 mm layer, printed at 20 mm/sec, .06 mm layer height.

 

 

 

[zews 1]

gr5,

I have done the UM2 Extrusion Test. My printer failed the test spectacularly! I have uploaded photos in the appropriate thread.

 

[gr5 2,167]

1) What temp did you print that cylinder?

It's supposed to be at 230C for a fair test. Looks like a pass to me. Anything above 5mm^3/sec is a pass in my book.

So you got moire. Still there. You also got strange bumps.

2) Is your shell at least .8mm?

Cura ignores lines if they are shorter than a certain distance or if combining two lines into one deviates less than some threshold it combines them. This creates artifacts like these bumps. I'm really not sure what to do about them. You could try a different slicer like the one that comes with repetier host maybe. Or you could try Cura version 14.03 which doesn't do quite as much combining I think. You can get older versions of Cura here:

http://software.ultimaker.com/old/

 

Actually if you really really hate those bumps and if you really hate the moire pattern I guess I would put my own pattern on there on purpose which would basically force Cura to print every line as it was in the CAD. Maybe add some interesting cross hatch pattern or something.

Regarding the top of the knob - I didn't realize it wasn't flat. because it slopes you get all those layers like a wedding cake. You can make that a bit better with thinner layers (.1mm) but then it will print much slower :(

I recommend 35mm/sec as a compromise speed as now I'm convinced printing slower won't help those bumps. It's a slicing issue.

 

[gr5 2,167]

I feel like the rabbi in the story where the dad complains that his one room house is too small for his family and the rabbi has him move in the mother in law, the goat and his brother and it just gets worse and then he tells the guy to move the mother in law, goat and brother out and now the guy is happy even though he is back to the original situation.

I like the print best so far when it had the moire pattern and had more polygons. Most people print flat sided objects and those come out nicer. But I can see that this subtle curve has it's own beauty to it and Cura shouldn't be changing/rounding/combining those polygons and should just print it the way it was created in CAD. This means you might want to switch slicers.

 

[zews 1]

1) What temp did you print that cylinder?

It's supposed to be at 230C for a fair test. Looks like a pass to me. Anything above 5mm^3/sec is a pass in my book.

 

I don't know what temperature I printed at. I assume the printer's default. I did not make any changes.

 

2) Is your shell at least .8mm?

 

Yes. The shell was .8 mm

 

You could try a different slicer like the one that comes with repetier host maybe. Or you could try Cura version 14.03 which doesn't do quite as much combining I think.

 

I was also beginning to think that it might be a slicing issue. I have netfabb Studio for Ultimaker. Unfortunately I cannot seem to be able to save the gcode. In the Toolpath tab of netfabb the "Save as .GCODE" button is greyed out. I also see a large warning icon (red triangle with red exclamation point) in the main window.

In the USB tab, I see the same warning sign. When I connect my printer with the USB cable and click "connect", something does happen. The light inside the printer goes off and back on, but netfabb still does not seem to see the printer.

When I open the Warnings window, it says a number of times "no COM device found!", this was before I had connected the USB cable. After connecting the printer with the cable the Warnings window now says "Device detected but not ready!"

 

How do I connect my printer to netfabb so netfabb can see it? I am running Mac OSX Lion, and the version of netfabb is Studio Basic for Ultimaker 4.9 (Demo) (Downloaded from the Ultimaker site.)

How do I generate and save the gcode with netfabb?

If I am successful in connecting the printer to netfabb, should I print from netfabb, or should I save the gcode and then open it in Cura to print?

And finally, ... netfabb keeps crashing on me.

It's now 2 AM. Time to call it a day.

 

[pm_dude 27]

Wait are you not using the SD card to trigger your prints? You should just put the gcode on the sd card and browser that gcode from the menu on the printer.

 

[zews 1]

pm_dude,

It seems that you are not familiar with netfabb, it doesn't work that way. It needs to be connected to the printer via USB cable.

 

[illuminarti 18]

If you just have the demo version of netfabb, you probably can't save the gcode. Pretty much no one uses Netfabb with an Ultimaker any more - the support for Ultimakers isn't that good any more, and people had poor experiences with it and with their support. AFAIK, nothing has been done to support Ultimaker 2's.

There are plenty of other free slicers inluding slic3r or Kisslicer. Another alternative is Simplify3D, which (like Netfabb) is a paid program, but works nicely for me.

 

[illuminarti 18]

As George said, the extrusion test is designed to print at 230º. So I suggest that you increase your temp to 230 (the default is and try it again, so that you have a meaningful benchmark.

 

[gr5 2,167]

Not sure what default temp is for PLA. I think maybe 220C.

 

[illuminarti 18]

210 in all the recent firmwares.

 

[zews 1]

I like the print best so far when it had the moire pattern and had more polygons. Most people print flat sided objects and those come out nicer. But I can see that this subtle curve has it's own beauty to it ...

 

I agree, of all the prints the one with the larger number of polygons is still the best. The reason the design of the knob has that subtle curve and the sloped top, is that I am copying the original power knob of my lathe, which is broken. I can't buy a knob off the shelf, and replacing it from the manufacturer in the Czech Republic is also not an option.

 

 

 

 

... and Cura shouldn't be changing/rounding/combining those polygons and should just print it the way it was created in CAD. This means you might want to switch slicers.

 

I tried a couple of other slicers with bad results.

I could not connect netfabb to the printer as it is supposed to via USB cable, and I was also not able to save the gcode after slicing, so I could not put anything on the SD card. From what I was able to find online, it seems that the version of netfabb I have does not support OS X very well or at all.

I also tried slix3r for OS X. That also did not go well. This software seems to have quite a bit of a learning curve, I prefer the simplicity of Cura. The scariest thing was that the print head does not start in the same place as normally, but in the far back-left corner, and when the print started, the nozzle slammed into the metal clip that holds the glass plate in place. My sphincter did not like that. It is probably possible to avoid that, but I would have to figure out how to do that in the software. The infill was also pretty strange looking, nothing like the clean squares that you get from Cura, but very weird looking honey combs.

I wonder if it would be helpful to send the STL file to Ultimaker and ask their support team what they think of it. Maybe it would help them to improve Cura if the moire pattern is in fact a slicing issue.

Other than that, I think I will just have to experiment with a bunch of different settings for temperature and printing speed. This continues to be very frustrating.

 

[zews 1]

In other news, ...

I printed the sample tube again, this time at 230 degrees. It still did not come out perfect. This time things started to go somewhat wrong at 8 mm^3/sec, and then it got progressively worse, although not as bad as the previous attempt. The mistakes were only to the left and right of the area where the text is, as well as exactly where the text is, not on the opposite side. I can upload a photo to the appropriate thread.

MeshLab was also not a great deal of help reducing the polygon count of the model. I followed the instructions on the Shapeways site exactly, and the best I could get was this. Different settings produced worse results.

 

 

[Blizz 53]

Zews: The purpose of the tube is to check extrusion, it does not need to be a perfect tube. It easily happens that the next layer doesn't attach.

As long as the strands of plastic are consistent in thickness and appearance the test should be considered ok.

[gr5 2,167]

Zews I don't think 3D printing is ever going to satisfy the level of perfection you are looking for. However, if you go back to the first knob you printed with the moire pattern, you can probably let it sit in a vapor of Ethyl Acetate to give it a much more polished look and smooth out those imperfections. I've seen lots of other people do this (with ABS and acetone - Ethyl Acetate works on PLA ) and it makes the parts come out very smooth and pretty.

acetone and ABS (this image gives you an idea of how much more "perfect" an imperfect print can be smoothed to):

http://boingboing.net/2013/03/03/smoothing-3d-prints-with-aceto.html

ethyl acetate and PLA:

http://www.printedsolid.com/smoothpla/

 

[zews 1]

Zews I don't think 3D printing is ever going to satisfy the level of perfection you are looking for.

 

You are right, I am a bit of a perfectionist. Take a look at http://www.abrasha.com I have been working with 3D printing for some time (Shapeways) and looked at getting my own printer since early 2012. At the time I did not think that the quality/resolution of the output of available printers would satisfy me. Finally this year I thought that the quality had improved enough that I wanted to jump in.

I am not at all disappointed, and realize that there is a limit in what any of these FDM printers can produce. I plan to use the printer mostly for making prototypes of my designs that will be produced in a variety of ways, i.e. hand fabrication, CNC machining, casting, high resolution 3D printing. I recently had this prototype Proof of Concept printed by Shapeways, which could never be printed on my printer. I'm fine with that.

 

 

I'm not disappointed with the print of that power knob either. I have been able to get the first layer smooth, so I know I can repeat that. I just have to learn to be consistent. The moire pattern was a big surprise and I tried to figure that out with your help and others in this forum. Now that a few people seem to think that the issue may be with Cura and not me, I think I will send the STL file to Holland and ask their opinion. Maybe it will help them to improve Cura if that is in fact the cause of the problem.

 

However, if you go back to the first knob you printed with the moire pattern, you can probably let it sit in a vapor of Ethyl Acetate to give it a much more polished look and smooth out those imperfections.

ethyl acetate and PLA:

http://www.printedsolid.com/smoothpla/

 

I knew that ABS prints can be smoothed out in Acetone vapor. I did not know that this was also possible with PLA and ethyl acetate. Thank you for that tip. I will give it a try.

I've got plenty of bad prints to try it on, without fear of ruining anything. :smile: