Need adjustments to improve print quality

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Re: Need adjustments to improve print quality

Postby roberlin » Tue Mar 12, 2013 5:50 pm

Assuming that it is a single layer wall (it sort of looks like it is but it's really thick?)
you now want to measure the wall thickness and compare with what it is supposed to be (slic3r includes the nominal wall thickness in comments at the beginning of the file).
Then you change your flow (either through the multiplier in slic3r or setting your firmware) to obtain correct wall thickness.

Could be your flow is way too high?
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Re: Need adjustments to improve print quality

Postby cozmicray » Tue Mar 12, 2013 5:51 pm

Seems like we have the same problems?

See "Cruddy prints"
http://buildlog.net/forum/viewtopic.php ... 2219b6f3dd

Been baffling me for 8 months now
Looking forward to working to great prints together

Ray
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Re: Need adjustments to improve print quality

Postby flurin » Tue Mar 12, 2013 7:30 pm

@tmccafferty
Check your wall thickness as roberlin described. The thickness with 2 perimeters, a layer of 0.25mm and a nozzle diameter of 0.35mm should be 0.39*2 = 0.78mm (approx. 0.8mm).

Here you'll find more infos:
https://github.com/alexrj/Slic3r/wiki/Calibration

Is your nozzle diameter 0.35mm?
Which firmware do you use?
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 9:06 pm

Ok, I figured out the half height thing and some of the roughness on the sides. I was skipping z steps. I had adjusted the current up between prints and apparently the drivers were getting hot and skipping about half the steps. I have it closer now. But the wall still has a few ridges on it and the cube is a couple mm short.

The gcode is moving the z axis at 7200mm/min. I can't find where this speed is set in slicr3 or marlin. Anyone know? I was thinking about slowing it down a bit. Maybe the accel is incorrect and making it loose steps. I can put dial indicators on it and jog at 12,000mm/min back and forth and it moves the correct distance and returns to zero.

Any ideas?

I have a .35mm nozzle. If I extrude a bead out in open air, it measures .45mm. Is this correct?

The cube is set for a two pass perimeter. It measures 1mm. Is this about right?

Thanks for the coaching.

By the way, I sent the wife for hairspray. It's the cat's meow. Does it work with ABS?
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Re: Need adjustments to improve print quality

Postby flurin » Tue Mar 12, 2013 9:54 pm

tmccafferty wrote:The gcode is moving the z axis at 7200mm/min. I can't find where this speed is set in slicr3 or marlin.

The value is in the marlin firmware > Configuration.h
I don't rember exactly the relation, I think it's the steps per unit. You can post your "Configuration.h" and I'll check your settings.
tmccafferty wrote:I have a .35mm nozzle. If I extrude a bead out in open air, it measures .45mm. Is this correct?

Yes, it's generally greater, the print width is essential, it should be approx. 0.4mm.
tmccafferty wrote:The cube is set for a two pass perimeter. It measures 1mm. Is this about right?

No, the width should be 0.8mm! reduce the extrusion multiplier from 0.8 to 0.65.
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Re: Need adjustments to improve print quality

Postby tmccafferty » Tue Mar 12, 2013 10:16 pm

Looks like "Travel" in "Speed for non print moves" sets the Z speed. I slowed it down to 40 but am still skipping steps.

It appears that my stepper drivers are overheating and skipping steps. I have dial indicators set up on the Z and you can see it skip steps (evenly on both sides). It gets wors as it runs longer. Guess I need to add a fan or try to optimize the current more. If I didn't have the wiring spliced and hidden in the frame, I think I would use the second extruder module and do the motors seperately. Somewhere in the marlin code, I saw a routine you can enable if your z tends to overheat. Maybe that will help. I hate for things to be on the ragged edge : :(

It should have been 20mm tall and it ended up 18mm with some double pass ridges going up the sides.

Getting closer though
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Re: Need adjustments to improve print quality

Postby flurin » Tue Mar 12, 2013 10:26 pm

Do you use RAMPS 1.4?
There is trimpot on the stepper driver board (pololu) for fine tuning.

"Remember to apply a heat-sink to the largest chip on the back."
Last edited by flurin on Mon Aug 05, 2013 6:56 am, edited 1 time in total.
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Re: Need adjustments to improve print quality

Postby brnrd » Tue Mar 12, 2013 10:56 pm

The default for Marlin is 5 mm/s maximum feedrate for z as defined in configuration.h:

#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 45} // (mm/sec)

The Ord Bot should be able to keep up with this speed.

The other two that would affect skipping would be the jerk setting which is set to a very low value of 0.4 mm/s

#define DEFAULT_ZJERK 0.4 // (mm/sec)

and the acceleration which is set to 100 mm/s^2

#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

Perhaps you changed these values.
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Re: Need adjustments to improve print quality

Postby tmccafferty » Wed Mar 13, 2013 12:13 am

Ahh....
I added a fan to the control board and the heat sinks are barely warm now. I also am allowing the Z_ENABLE_LATE function to run. Now I am not skipping steps. Much better results
!
DSCN3309.JPG
20mm hollow cube

there is still a little bit of pucker in the corner. The 2 layer wall is .8mm now and the dimensions are 19.95 x 19.95 x 19.82 high. I assume the height is off a bit more because the first row is printed at 60%. Is that correct? Would you tweak anything else to improve dimensions or is that pretty much what you can expect?

One of the things I noticed is that if you look at the brim, the rows arn't "smushed" together. The bottom of the cube is two layers and I can see light through it. Does this mean my Z is too high? It is printed at 200 deg with a desk fan blowing on the bed.

brnrd wrote:The default for Marlin is 5 mm/s maximum feedrate for z as defined in configuration.h:
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 45} // (mm/sec)

Mine is {500,500,25,45} so I will change it
everything else seems to be in line.
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Re: Need adjustments to improve print quality

Postby tmccafferty » Wed Mar 13, 2013 12:27 am

flurin wrote:The value is in the marlin firmware > Configuration.h
I don't rember exactly the relation, I think it's the steps per unit. You can post your "Configuration.h" and I'll check your settings.


Here are my config files. If you don't mind, take a look and let me know if there is something else obvious I need to deal with.
Attachments
Configuration_adv.h
config_adv.h
(11.75 KiB) Downloaded 953 times
Configuration.h
config.h
(11.96 KiB) Downloaded 1026 times
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