rough edges on print

Hi all,

I was wondering if someone could provide any suggestions on why the walls on my 3d printed parts (from my Prusa i3) have been coming out so rigid and rough.



So far I have tried reducing the extrusion multiplier as well as reducing the external perimeters speed in Slic3r, but neither have seemed to help.

According to the wiki reprap troubleshooting guide, I have the following issue: Material Feed, Excessive
[reprap.org]



The guide says to reduce flow rate setting for perimeters, but I cannot seem to find where this setting is in Slic3r.

Other things I have already tried are changing acceleration rates and XYJerk in Marlin.
Here is the code I have changed, but it has made little difference on the print.

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4040,744} //{80,80,4000,237} //{78.7402,78.7402,200.0*8/3,760*1.1} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3500,3500,100,2000} // X, Y, Z, E maximum start speed
//#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.

#define DEFAULT_ACCELERATION 2000
//#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 2000
//#define DEFAULT_RETRACT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for retracts

//#define DEFAULT_XYJERK 20.0 // (mm/sec)
//#define DEFAULT_ZJERK 0.4 // (mm/sec)
//#define DEFAULT_EJERK 5.0 // (mm/sec)

#define DEFAULT_XYJERK 10.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)

Thanks for any insightful information
Jeff

looks like the same problem. [forums.reprap.org]. Z axis artifacts

I agree - it looks like Z axis artifacts. This is usually caused fighting between the Z smooth rods, the Z screws, and the Z coupler. In theory, the Z smooth rods keep things aligned, but if your Z screws do not turn uniformly, they can exert pressure on the entire gantry, causing it to move left, right, forward or back. The main culprit in my case was that the coupler between the motor and the screw did not properly hold the screw so that it would be exactly concentric with the motor shaft.

This can be hard to see when you are moving the minute amounts that a single layer change represents. To get a better view if this is your problem, move the Z axis as far up as it will go, and then home the Z axis. Carefully watch the turning of the screws. There should be no wobbling at all.

The final remedy in my case was to order some new motors that had the lead screws integrated into the motor shaft - the screw was actually an extension of the shaft and no coupler was necessary. I got them from robodigg, and thus far (it's only been about a month) I have been very happy with the improvements.

Edit:

Check out the first photograph in this post. I'm not sure it they're exactly the same, but you can see they type of motors I am talking about with the integrated shaft/screw.

Edited 1 time(s). Last edit at 11/09/2014 10:30PM by jbernardis.

Thanks guys, I ended up fixing the issue. One of the couplers was not very tight and that seemed to fix most of the wobble in the screw.

However, I do have one other question.. There are two motors for the Z-axis on the prusa i3, and one of my motors seems to wobble just slightly. The wobble in the motor is more noticeable when I move the z-axis 10mm. I have checked to make sure the motor is tightly mounted to the frame/z-holder and made sure the coupler is tightly fastened to the z screw. I have also tried changing the pot on the stepper drivers, but that didn't seem to help either.

Overall the slight wobble in the motor is not affecting my prints, but I am unsure why one motor has a small wobble while the other z motor is perfect.

Anyways, thanks for the help