Monday, Feb 19 2018
gap
I’ve been trying to fine tune slicer/extruder paramaters and noticed that I’m getting little holes where the filament stops flowing for a short while. The picture happens to show the issue during printing of a skirt for a test print. I’m using it as an example instead of the test part because the skirt is easier to photograph.
The gap is about 1.6mm in length. That is typical to what I’m seeing in the walls of a single wall test part. It does not seem to be retraction related as the gap’s occur at random locations, sometimes many tens of mm away from retraction points.
I’m guessing it is something with my extruder. I changed the extruder housing last month. At that time I thought the tension spring might have been too tight. Perhaps I should put the stock part back to compare. I can see indications of the issue in older prints, but not to the extent I’m seeing them now.
I did remove the damper from the extruder stepper so I could put back the extruder hand wheel. I also switched out the bowden tube, installing new tubing from Capricorn.
Saturday, Feb 24 2018
Changes
Original Extruder Housing
Test print with holes
The first picture shows the changes mentioned above. Today I removed the printed extruder housing and re-installed the original. My workaround to keep the original filament detector in place is a drop of super glue.
The result? No change. I can still see the small holes in the pictured test piece. Most are about 1 mm wide. Since I can feel marks on the filament from the extruder drive gear it leaves me thinking that the spring is too tight. I’ll probably have to go to the hardware store and buy several springs to get one that is right – assuming this is a spring/chewed filament issue.
Another change that made no difference is installing a snafu modification of the TH3D modified version of Marlin 1.1.8. I didn’t expect that to make any difference. I started with the TH3D version because I knew it was set up well for the CR-10S. My changes to the config file are quite simple. I added the following near the top of the file:
//===========================================================================
//============================ SNAFU Configuration ===========================
//===========================================================================
/*
* snafu specific options -- put here instead of uncommenting out below
* so I have them all in one place.
*/
#define CR10S
#define USER_PRINTER_NAME "SNAFU CR-10S"
#define MESH_BED_LEVELING
#if ENABLED(MESH_BED_LEVELING)
#define MESH_INSET 30
#define GRID_MAX_POINTS_X 3
#define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X
#endif
#define LCD_BED_LEVELING
#if ENABLED(LCD_BED_LEVELING)
#define MBL_Z_STEP 0.025 // Step size while manually probing Z axis.
#define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
#endif
#define LEVEL_BED_CORNERS
snafu
That gives me the MESH_BED_LEVELING option. Fun stuff. I also changed the startup screen to make it more personal. My changes are in a local git branch to make it easy to track changes to the main branch on github. Update: I’m now tracking the bugfix-1.1.x branch of the official Marlin release: https://github.com/MarlinFirmware/Marlin.