Need adjustments to improve print quality

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Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 12:36 am

Thanks to J-Head, I am finally up and printing. I didn't have much luck with ABS sticking so I tried PLA on painters tape. That is sticking fine so I'll do that for now.

I have been tweaking some settings mainly speed and temperature on a 20mm calibration cube. Going from 185 to 190 on temp improved the print some. It made the side ridges smoother. I am using a heated bed at 60. I started at slicr3 default of 30mm speed which is what is photographed. I tried 60 and the sides are similar but the top surface is not as good. I am doing .2mm layer.

DSCN3300.JPG
20mm cube cured corners


My biggest disappointment is that the corners are not sharp and the corners are curled up. What adjustments do I need to make to flatten and sharpen the corners?

Any other important slicr3 settings for PLA would be appreciated.
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Re: Need adjustments to improve print quality

Postby kongorilla » Tue Mar 12, 2013 12:50 am

Corners pulling up like that are fixed by using a fan to cool the PLA quicker. Setting the temp back down to 185 might help the corners, too.
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Re: Need adjustments to improve print quality

Postby Looper » Tue Mar 12, 2013 1:02 am

tmccafferty wrote:Thanks to J-Head, I am finally up and printing. I didn't have much luck with ABS sticking so I tried PLA on painters tape. That is sticking fine so I'll do that for now.


If you have glass on your heat bed get a can of "Aqua Net Unsented Extra Super Hold" hairspray. Not sure who to give the original credit to but Bart posted it up one day and after having issues with the painters tape I tried it and I'll never go back.

Image
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 1:44 am

Why aren't the corners sharp?
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Re: Need adjustments to improve print quality

Postby kongorilla » Tue Mar 12, 2013 3:19 am

See how the corners are sharp on the first layers, then get progressively worse? As hot end travels around the perimeter it can tug slightly on the layers below. If those layers are still soft, then they get pulled up a little. The resulting inaccuracy tends to add up, so in this case the corners get progressively messier. Using a fan makes the layers solidify more quickly, so this lifting tendency is greatly reduced.
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 3:35 am

Ok, thanks. I'll work on getting a fan set up. When I had just a QU-BD, after much effort, I got one calibration cube from ABS. Although it had lifted off the glass a bit, it had real nice crisp corners and good side wall quality.

If you want the sides smoother, is that layer thickness?

I sure hope there is a path to consistent recipes. With so many seemingly finicky variables at play, I don't see how you folks that produce a lot of parts get it done. Man, cnc routing is a piece of cake compared to this!
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Re: Need adjustments to improve print quality

Postby flurin » Tue Mar 12, 2013 9:10 am

tmccafferty wrote:Any other important slicr3 settings for PLA would be appreciated.


My proposal:

Try first to print a hole cube (edge length=30mm)
CubeTest3.JPG

with following slic3r settings:

; layer_height = 0.25
; perimeters = 2
; top_solid_layers = 0
; bottom_solid_layers = 2
; fill_density = 0.0
; perimeter_speed = 40
; infill_speed = 60
; travel_speed = 180
; scale = 1
; nozzle_diameter = 0.35
; filament_diameter = 1.75
; extrusion_multiplier = 0.8

additionally with a Brim of 3mm
Temperature: 200 degrees C
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Re: Need adjustments to improve print quality

Postby cvoinescu » Tue Mar 12, 2013 9:54 am

Unless you cool it below a certain point, PLA remains a semi-solid jelly, which flows and sags. You need a fan to blow on the print. Not a lot -- gentle airflow is enough. You may want to try it with a cooler, or even cold bed, too; you don't really need 60°C for PLA.
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 5:21 pm

flurin,

I created a 30mm cube and ran it as you suggested. Here is the results:
DSCN3301.JPG
partial print 30mm cube 200C

The corners are sharper, but the sides are rough. I have a desk fan blowing on the bed. Results are nothing like the photo you osted.

For some reason, the print stops at 14.75mm high and the head moves close to home but not exactly. I have a gcode viewer that I use with my router. When I use it to do a backplot of the file, it shows the full cube and at the end the head should move to the last y and x0. I thought maybe the printer just had a glitch, but it did it in exactly the same place on a second attempt.
Attachments
DSCN3303.JPG
print stops half way through
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 5:23 pm

The Belts are good and tight and I did a dial indicator test on position repeatability with a dial indicator at jog speed of 3000mm/min. It seems rock solid.
Attachments
DSCN3302.JPG
repeatability test
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