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Jul 2017
13 days later

I should have added that when I print at 0.2mm, I see no blobbing and the bottom layers are perfect. When I print at .15mm I start to see traces of the blobbing. The higher the resolution the worse it gets.

I also forgot to mention, if the part is 100% infill, the blobbing is very bad. If the part is 0% infill then the lower layers are perfect with no blobbing. This may help if you decide to pursuit a true fix, and not just a work around like I am doing.

Let me know if you have any questions or ideas.

Woody, one thing to look at is how the filament is extruding through the nozzle, i had noticed if their is any friction on the inner metal tube wall (the metal tube is located about the aluminum block that the actual Nozzle screws into, on the aluminum block, at one you screw the nozzle and the other end is screwed into the metal tube.), if their is friction you will get blobbing. Also note that when running a print you may hear some what of a clicking sound now and then at the extruder stepper motor. this is caused by having too much friction (blockage) within the extruder tube, (not the nozzle). The quick fix to this problem is by doing the following: NOTE you will be doing steps 2 through 8 with the extruder preheated to 220c.

1. preheat your hotend to about 220C

2. remove the filament

3 remove the nozzle

4 using a drill bit approximately 0.4 or 0.5mm see if you have clear passage up through the opening where the nozzle was removed.

5 if you can not push the drill bit up, then twist the drill but into the clogged filament plastic inside the metal tube and then pull down to remove the plastic.

6 you may have to do this several time to clear the blockage.

7 once the blockage is removed, reinsert the filament like normal and feed the filament by hand all the way through the bowden tube until you see the filament come out of the hot end, (note you are doing this WITH OUT the nozzle being attacked, you wan to see if their is clear passage through the metal tube with no friction)

8 Once you have successfully achieved good results you can now reattach the nozzle.

NOTE: this is a temporary fix to the problem, the problem occurred because the inner extruder tube does not have a low coefficient of friction allowing filament to build-up on the tube wall and then prevent flow of the filament.

one solution to help correct this problem is to upgrade the hotend tube and extruder nozzle to something like Micro Swiss or similar that is a steel tube having a low coefficient coating.

Did you by any chance try loosening the wheels on the rail opposite the z stepper? I found this post on reddit, but as stated above can’t immediately make a change.

Unfortunately, I’m not entirely sure what the OP is describing when he says he “loosened it up” seems kinda vague. I posted a comment there to try and get some clarification.

Edit: Seems like OP posted a bit more detail later in his post.

jtkirk

Wow!!! Great info. I have to admit, the first thing I did when I got the printer was to tighten all the rollers. It was recommended by several YouTube videos. I may have caused this issue. Ugh! The post you found makes perfect sense. Since I tightened the rollers, I bet the side opposite the stepper motor doesn’t move right away until enough pressure is applied to get it to roll. This would reduce the Z axis movement at the nozzle. This would definitely cause over extrusion at the lower layers of a print. I believe you found the answer!!!

To fix the issue, do the opposite of what they say to do in this video. The link will take you straight to tightening the rollers. For me, tightening the rollers is what caused the issue. If you tightened them when you got the printer, you will want to loosen them back up. If you didn’t tighten them like I did, they may still be too tight. Specifically, loosen the rollers on the right side of the gantry. I attached a picture for clarification.

https://youtu.be/Cdkb_ILCptw?t=4m40s 901

Thanks again for finding this.
1501437125378560186.jpg

Awesome! Thanks for the clarification. I should be trying this out in the next week or so. I really hope it fixes the issue!

The fix is confirmed. I took the bracket off of my printer and figured out how to tighten and loosen the rollers. I can see how I made my mistake. I didn’t understand how to properly tighten the rollers. There is only one adjustment screw that needs to be adjusted. I have attached a picture for clarification. This fitting is intentionally off center. It doesn’t need to be tightened, just turned. On mine, I turned the fitting until the roller was very loose. Then I slowly turned the fitting until the roller came in contact with the vertical support post. I tightened it a little bit more until the roller felt like it was grabbing on.

I started a test print at .06mm layer height. I stuck around until the bottom layers were printed. Looks perfect with no blobbing or bulging at the bottom. :slight_smile: I will post a picture when I get home.

Hey Woody! Not to be pushy, but I’m quite eager to know if it worked on your next print?

Joshua,

Success!!! The lower layers are perfect!

On a side note, I am seeing some ringing on the X and Y axis (see pic). I may have loosened the roller too much (or I’m printing too fast at 50mm/s). No biggie. The ringing I can fix.

Now that the issue is fixed, I am planning on reprinting everything I have ever made. Most of my prints have the blobbing ring around the bottom.

I hope this fix works for you as well.

Woody