Help identify problem.

Hello

Below is a summary from my previous post at: [forums.reprap.org]

Problem
Following is the desired print:
[imgur.com]

Following is the incoherent output:
[imgur.com]

Printer Settings
* 0.3 Nozzle, with a 0.2 layer height/
* First Layer Width: 200%
* PLA with 90C bed temperature and 205C extruder temperature

Calibrations Complete
1) Extrusion steps. 120mm of strip, extrude 100mm, 20mm remaining.
2) Nozzle height. At 0.1mm nozzle height, moderate friction exists between a 0.1mm paper and the nozzle.

Previous post suggestions
* Possibility of slicing problem? I don't think this is the case as in the test data below, when the extrusion multiplier is increased, it no longer looks hexagonal, and becomes coherent with higher multipliers.
* Either belt or gear attached to motor is slipping? I checked this by placing my finger on both the gear and the motor shaft,and try to feel for slippage as it was moving. I did not feel slippage. The same with the belt, held the belt and the gear, no slippage was felt. If you disagree with my method of figuring out slippage please let me know.

Test Data
Here is an album containing all test data pictures: [imgur.com]
As the extrusion multiplier increases the print begins to look a lot better.

Question
I need your help debugging what the problem is gentleman. I have not been able to figure out what the problem is.

Thank you for your time.

Additional Notices:

*The inner 3 circles are missing in all of the pictures. I can probably fix this by enabling skirts and making sure the extruder properly begins to extrude before starting the actual print, however I dont feel like I am fixing the problem if i take this fix.
*The print begins to look good at Extrusion Multipliers of 3.0, however the software suggests that there is a problem if I am having to operate at greater than 1.2 and suggests I calibrate extrusion steps when i already have. I am begining to think during operation voltage drops begin to happen? Thoughts?

Hi,

there are basicly Feedrate, Acceleration and Jerk that could cause this.
I would start with Acceleration. The Default Value is 3000 for DEFAULT_ACCELERATION, and DEFAULT_RETRACT_ACCELERATION. I had to turn it down to 1500 to make my sudden nossle jumps disapear.
If this doesn't work lower the Feedrate a bit. And if this doesn't work lower the XYJERK value.

Hope that helps.

Hello,

I have more data from your suggestion.

Firstly modifying DEFAULT_ACCELERATION and DEFAULT_RETRACT_ACCELERATION, seems to effect the infill the most. By default these variables where 500, but it looks like the value that benefits me the most is 2000. Album [imgur.com]

Changing the Feedrate from 22 to 44 to 100 made no real improvements on the output.

Changing the Jerks from:

XY 20 to 30 to 40 to 50
Z 0.4 to 0.6 to 0.8 to 1.0
E 5 to 10 to 15 to 20

Has had no improvement,

As for all future considerations the firmware variables are now:
DEFAULT_MAX_FEEDRATE {250, 250, 2, 22} // (mm/sec)
DEFAULT_MAX_ACCELERATION {2000,2000,5,2000} // X, Y, Z, E
DEFAULT_ACCELERATION 2000
DEFAULT_RETRACT_ACCELERATION 2000

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

Does anyone have any other suggestion?

It could also be a print bed adhesion problem. Please let us know what print bed surface you use and what type of adhesion agent you use. Plain glass? Used any solvents to remove vinger oils? Using hairspray, vinegar, glue stick etc? heated bed/temperature?

I usually use 15mm/s first layer with good results.

See if the printer makes a perfect circle and the filament 'cuts corners'. That could explain why the circles have corners.

What is the extrusion width? For a 0.3 nozzle I'd try 0.5mm first. With a layer height of 0.2 this should create enough pressure for good adhesion.

Also, measure the printed layer height with a good caliper to see if it is correct. If you use your firmware with an EEPROM you can set Z Offset in the control/motion menu for easy adjustment. If the Z height is still slightly too heigh you can lower this value by 0.1 and try again.

Have you set your filament diameter right in your slicer?