lousy prints, Please help,

Hello, again, (sorry, but I'm really starting to get discouraged),

I had a previous post titles 'wavy lines'. I'm starting a new one because that issue has been resolved, and I was able to print a perfect test cube that I was very happy with.

I then decided to reprint my cooling fan duct, and it looks horrible. I'm using the same setting as for the test cube. The duct itself looks ok (the skinny sides printed with one perimeter, that's why it looks the way it does, but that doesn't bother me) but the base of it that the fans attaches to is terrible. Now I under stand that the test cube is just one perimeter, and the base of my fan duct is 3 perimeters with a 20% infill, so it makes since that the problem is with the inner layers.

Here are the basic settings I'm using:

Layer height: .2mm (first layer .25)
speed; perimeters 40mm/s
small p. 40mm/s
exterior perimeters 50%
infill 50mm/s
solid infill and top solid infill 20mm/s
gap fill 35mm/s
first layer speed 50%

acceleration 0 (default)

overlap, was at 15. I set it to 5%

filament settings:
dia 1.77 (measurement from calipers)
extrusion multiplier 1.4 (I set that to get .4mm wall thickness)

temp:
extruder 1st layer 190, other layers 185
bed 1st layer 60, other layers 55

in the lcd controller I set the jerk to 10 (it was 20), that made the test cube almost perfect, so I now have it set to about 7.

Parts of the fan duct look like it's over extruded, parts of it look like it's under extruded. the top layer is not smooth. It's just a mess. And I am new enough to this to know that it's not right, but I have no idea what to change to make it look good.

thanks in advance for any help or advice,
Scott

What filament are you using? When I used Inland white filament from Micro Center on my printer, the prints came out looking like your fan duct. Switching to a different spool of filament fixed the issue for me.

I'm using colorfabb. I just put on a new spool. The test cube was from the old spool, and the fan duct is from the new spool, but it's the same stuff from the same supplier.

None of my previous prints were perfect, and I just started focussing on fine tuning to get a perfect print, but this looks worse than any print I have ever done.

Since the round part of duct looks ok, I think it's pushing out too much plastic for the inside perimeters and infill, but I'm not sure, and if it is, I don't know how to fix it.

I'm not good enough with this yet to just look at a print and know what settings to adjust to make it better.

Thanks

You really need to adjust your extrusion settings, it looks like the infill is far too much.
But since you just started with it all: Did you do a proper calibration of the whole printer?
If not start with that and maybe your problems will be gone already.

I calibrated the printer according to folgertechs instructions and YouTube. My first prints were ok. Not perfect, but not bad. And then I decided to fix a few issues. First it was over extruding a little bit. I fixed this by measuring the filliment with calipers and tweeking the extrusion multiplier. After that, my test cube had a perfect wall thickness, but a wavy pattern was now showing. I fixed that by tuning down the stepper driver. Now my test cube was perfect. But when I printed this new part, it's terrible. The only difference between the two, is the infill.

I read on another post that Repetier hosts auto default settings for extrusion width are no good and to put in your own. I put in an extrusion with of .48, and lowered the extrusion multiplier, reprinted the Dan duct, and it's near perfect. It's better than anything I have ever printed, and looks almost as good as anything I have seen printed.

It just has one minor problem, the extrusion width is slightly too small. But I know how to ajust that now.

If I have any issues making those last (hopefully) ajustments, I'll let you all know.

Thanks again

try setting your perimeter / infill overlap to -20% ( yes, slic3r does accept a negative value )

I think you have calibration problems. I don't know where the idea of measuring wall thickness came from for calibrating, but it's a bad idea. It is too difficult to measure a single wall thickness accurately and precisely. If there's any Z wobble the wall will measure thicker than the lines that make it up. When you calibrate you want everything set at the base point- set extrusion multiplier and flow to 1 and leave them alone. Measure your filament diameter in 20-30 places and with the caliper set at different orientations on the filament and calculate the average diameter. Use that average when you calibrate.

If your machine consistently over or under extrudes, the way to fix it is to address the real problem and calibrate. Triffid Hunter's calibration guide, especially the "E Steps Fine Calibration" section will get your machine calibrated right.

Things like flow and extrusion multiplier are used to tweak prints on the fly when you reuse gcode that was sliced for one diameter but now are running filament of a different diameter. Read through the stuff about volumetric extrusion- you set one filament diameter when you slice, then set the actual diameter when you print, either via host or LCD panel depending on your firmware (smoothieware has a filament diamter input via the LCD/encoder panel). By using volumetric extrusion, your gcode becomes filament diameter agnostic. You can reuse the gcode with any diameter filament. Going further, if you set the bed and extruder temps to 0 when you slice, you then set them when you print, depending on the material you are printing. If you use both of those tricks, your gcode will be usable for any material and any diameter filament.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Well it's in the middle of a four hour print, and so far it looks great.

Thanks again for your input,
Scott

Quote
the_digital_dentist
I think you have calibration problems. I don't know where the idea of measuring wall thickness came from for calibrating, but it's a bad idea. It is too difficult to measure a single wall thickness accurately and precisely. If there's any Z wobble the wall will measure thicker than the lines that make it up. When you calibrate you want everything set at the base point- set extrusion multiplier and flow to 1 and leave them alone. Measure your filament diameter in 20-30 places and with the caliper set at different orientations on the filament and calculate the average diameter. Use that average when you calibrate.

If your machine consistently over or under extrudes, the way to fix it is to address the real problem and calibrate. Triffid Hunter's calibration guide, especially the "E Steps Fine Calibration" section will get your machine calibrated right.

Things like flow and extrusion multiplier are used to tweak prints on the fly when you reuse gcode that was sliced for one diameter but now are running filament of a different diameter. Read through the stuff about volumetric extrusion- you set one filament diameter when you slice, then set the actual diameter when you print, either via host or LCD panel depending on your firmware (smoothieware has a filament diamter input via the LCD/encoder panel). By using volumetric extrusion, your gcode becomes filament diameter agnostic. You can reuse the gcode with any diameter filament. Going further, if you set the bed and extruder temps to 0 when you slice, you then set them when you print, depending on the material you are printing. If you use both of those tricks, your gcode will be usable for any material and any diameter filament.

As far as measuring the wall thickness, I learned that at the university of you tube. Basically, you calibrate the extruder steps, then for a fine tuning, print a single wall object and using calipers, measure the thickness of the top layer of each wall. Take an average of these and compare it to the wall thickness the g-code states that it should be. Then you divide what you should have by what you do have to know how to set the extrusion multiplier.
This method worked perfectly for me.

My problem ended up being Repetier hosts default settings for extrusion width was way too far off. When I put in a value of .48, it prints perfectly.

From what I have seen on YouTube, and various forums, it seems like everyone has a slightly different idea of how to use the extrusion multiplier. I don't know enough about it to know the exact intended purpose, and how to use it, but for me, what I did worked.