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Print quality good and bad on same part ??

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PrintMan

New Member
#1
#1
Hello All,
I just got my gMax 1.5 XT with dual extruders built and performed my first test print. I am using Repetier-Host V1.0.6 with Slic3r 1.1.7 and loaded the gMax 1.1.7 Slic3r config files. I printed a square box 50.8mm x 50.8mm x 50.8mm. The box has a 1.5mm wall thickness. It is 3 times my .35mm hotend nozzle size. The front facing wall of the box has blemishes but also has really good quality in between. Anyone have this issue and found a fix. The back facing wall is perfect with absolutely no blemishes. The right facing wall was just about perfect as well with 3 small blemishes. I used the colorFabb PLA black that came with the printer. The hotend temp was set for the default PLA in slicer of 208c. When printing the temp went as low as 205c and would swing to 210c. It seems to swing 3c above or below 208c. Is this normal? I would not think this would be the issue. Thought maybe if the bed is not completely level this could happen? What if the left front corner of the bed was a little higher? I leveled the bed as good as can be so it should have been level. I also would observe the blemishes when they were happening on the front facing wall. The extruder would be moving along and a blemish would happen in the middle of a straight line. The extruder would not stop or pause or move from the straight line until it got to the corner. I did notice that when it printed the outside layer that it went half of the speed of the inside layers. Also the inside walls all look really good like the outside back wall. Thanks in advanced :)
 

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mwu

New Member
#2
#2
Looks to me like filament that has too much moisture in it causing steam to disrupt smooth extrusion. Why it might not happen on one side, I am not sure so that might not be the case here.
 
crussell

crussell

Member
#3
#3
In slicer, under Print Settings >> Layers and Perimeters >> advanced (all the way at the bottom), make sure you have seam position set to "aligned" and not random. That looks like it's starting each layer at a different position.
 
grumble

grumble

Member
#5
#5
When mine was doing this during the calibration phase I just dialed up the power to the extruder and that solved my problem. It only took maybe a 1 degree turn in the clockwise direction.
 
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Spudwheelie

New Member
#6
#6
That looks like the filament feed stepper motor is skipping. A higher temp, and/or lower cooling would help for sure. You could also try slowing down your print speed. As for why it only happens on one side is possibly the bed not being completely level. One side is pushing into the extruder more than the other causing more resistance for the plastic to flow.
Listen for... TICK, TICK, TICK noise from the filament feed stepper.

Keep us posted on how you fix it!


EDIT: I want to trash the bed not being level as the cause for the bad quality on one side and not the other. The part is usually evened out after the first few layers. Instead I am thinking that the the extruder started it's path on the side with good quality and finished on the side with the poorest quality.
 
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PrintMan

New Member
#7
#7
I decided to first try and run the same program without any changes to see if the blemishes came back in the same places to see if it was a model problem. At the same time I also would pull some slack out of the spool so it would not have to pull the spool (trying a little to what grumble mentioned before I turned up the extruder power). I ended up getting about 60% less blemishes. But I then ran another test by turning up the extruder power and I was still getting blemishes. I set extruder power back to normal. I just noticed my Y carriage v-groove wheels are not all seated good in the aluminum grooves. The wheels catty corner to each other had a small gap away from the aluminum on the top part of the v-groove. I tightened and trued up the Y axis. That did the trick!!! I think.... I made one change to my slicer program which was to set Gap fill under speed to 0 so it would cut the print time in half. I am going to run the original program with the original slic3r setting I used to make sure the Y axis was truly my problem. Ran out of time tonight. The picture is from the front. Perfect!
 

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GORDON.LAPLANTE

GORDON.LAPLANTE

Administrator
Staff member
#8
#8
Great work. The print looks much better.

For the gap fill, the new versions of slicer handle it much better. Instead of a rapid jitter the gap fill is now replaced by a single line. This means you can turn up the gap fill speed to match the standard speeds and not lose time or shake the printer apart.

Also, if you lower the acceleration it may help you get sharper corners without the slight rebound as it changes direction.
 
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PrintMan

New Member
#9
#9
I found some more interesting results. I performed the exact same original slicer settings after truing up and got the same blemishes. Seems to be a slicer issue and absolutely no issue with the physical printer from what I can see so far. So then I decided to perform a test with Gap fill set to 150 under speed settings in Slic3r and I got a good print with no blemishes. I have always been using the 05mm Medium Quality Fast printer settings. Then I performed another test with the 05mm High Quality and set the Gap fill to 85 and got another good model with no blemishes. Also, during all this testing I have set Infill: Fill density to 100% so I could get 3 solid lines for the walls when testing. Maybe all this gap fill changing is just due to the fact that I am performing a very specific test scenario. But I guess it is good to know.

I have had slight waves in the walls of all the tests and now I want to remove those as well. I have tightened up the x and y belts as best I can. Might end up remove the tension spring to see if that helps. I will play with all the speed acceleration settings to see what I can come up with there. I have some walls on the same model that have no waves while other walls on the same model have them. I am assuming it is another slic3r tweak to be found.....

Anybody know of any good wave removal Technics?
 

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crussell

crussell

Member
#10
#10
From that orientation, does the printer move clockwise or counter clockwise? In other words, is the banding happening right after is rounds the corners? If so, turn down your acceleration settings in slicer. I have a heavy modified bed, so I'm at about 150.
 
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