Answered Odd filament problem - PLA

First a little background. I bought a used Robo 3D kickstarter and have added auto level, E3D V6 hotend, linear rod Y axis and just installed lead screws with parts from China from the thread in the upgrade forum. I've had several issues since I bought the printer, but didn't want to post anything until I got my mods all installed.

First issue is an odd pattern of filament lay down. I'm using Matter Control with some modified settings as I made changes to the hardware but nothing major. The issue was seen using the Robo PLA black filament that I was given with the printer, no idea how old or how it was stored. The issue also shows up on the Robo PLA blue filament (blueberry smellament actually) that I just purchased.

I thought it might be an extruding issue, but the pattern doesn't seem to match the rotation of the hobbed bolt. I checked the tension of the filament, and it doesn't seem to be related to tension. I've calibrated the extruder as it was 8mm under on 100mm extruded, adjusted in the firmware. I'm running the E3D V6 with the 'sock' and currently have Matter Control set to 200.

Any ideas on what might be causing it would be greatly appreciated!

 

What layer(s) does it happen on? First or all?

 

All layers.
What I was printing in the picture was a case for an LCD display. The problem continued when it finished printing the large flat part and was printing the side walls, leaving horizontal lines of weak areas.

 

I have not. It is on my list of things to do. Here I printed a spool holder with oiler but I haven't used the oiler. I'll give it a shot!

 

I added a piece of sponge with some canola oil and it didn't seem to change the behavior. Since I didn't season the nozzle when new, I added a little extra oil to the filament right above the extruder to get a bit more to the nozzle while I sent commands to extract about 100mm. I then printed the backside to the LCD case from the previous pictures and had the same results.

You can also see the warping that started my journey into upgrades. The filament sticks to the blue tape, but will actually pull the tape off the bed. Sad to see the same issue after spending a couple hundred on upgrades, but there you are. Running with no bed heat, as sometimes the bed will heat but the hotend will not, sometimes the reverse and sometimes neither. I'm starting to wonder if it's a power issue or ramps board problem. I've attached another picture showing some overhang stringing.

Diagnosing problems after making so many changes to a printer that was used to begin with has me chasing my tail.

 

Now that I'm starting to print from SD card on the smart LCD, it's quieter in the room. I've just noticed some popping or snapping sounds. At first I thought it was the fan shrouds moving over raised filament causing a clicking sound but I now wonder if it's from printing the PLA too hot. I had been using 200, so I've lowered it to 190 and am printing some cable chain links. I still hear the popping, quite a bit of it in fact.

I'm using the E3D V6 with sock. I wonder if I need to either remove the sock or drop the temp even more. I think I read that there's a min temp setting, not sure what it is although I'd guess it's in the config.h file. I think taking the sock off while keeping it at 190 might be the next test,

 

Don't tell me that, I live in the pacific northwest! I'd only be able to print for the couple weeks of summer we get!

Seriously though, I decided to take the blue tape off the bed and try using the heated bed to see if it would help prevent the warping. Unfortunately it wouldn't increase in temperature. It had been intermittent since I got the printer, so I had disabled it in Matter Control and used blue tape instead.

Tonight I decided to take the leap and swap out the ramps board. First I replaced the bed MOSFET with an IRLB8743, then I swapped all the parts to the new ramps and checked the old board since I had it out. As I was checking it, I found a suspicious solder joint. It turns out that one of the leads of polyfuse F1 was loose enough to wiggle up and down.

No time to try it out tonight, I'll try it out tomorrow.

 

Replaced the ramps board and now the hotend and bed heat as they should. Still can't print anything without gaps. I tried using heated bed and hairspray today for the fist time and it seems to work pretty good, although all I did was some small cable chain pieces. Giving up on printing a cable chain for the moment as 9 out of 10 break when removing from the bed or are too weak due to layers not adhering where the filament has the problem shown above.

Forgot to mention that before I did the lead screw upgrade I printed the cable chain extruder stepper motor cover with a brand new roll of esun PETG (my first try of PETG) and it showed the same symptoms.

I received some generic nozzles with the printer but the threaded portion isn't as long as the E3D, so I'd have to take the hotend apart to refit the heat break to the shorter nozzle. I decided to just order another E3D nozzle instead. So close!

 

I raised the hotend and extracted 100mm of filament while watching it. It was definitely not a uniform extrusion. I did it about 5 times and the results were the same. Taking the filament off the bed and examining it shows definite areas of smaller diameter. There seems to be a small area every 11mm to 12mm that's too thin. It also happens occasionally in other areas as well.

I wonder if I nicked the hobbed bolt when drilling the carriage for the E3D V6, and that's where it's under extruding. Still could be a microclog as well. Might be incorrect tension of the sprung screws. Could be bad filament. Could be the alignment of the planets. Still trying to narrow it down!

 

Well, I now have 2 Robo 3D's! I saw a local ad for another used one but this one was an R1+, not another Kickstarter. After cleaning it up (tons of grease on all bearings) and fixing the left Z end stop bracket that was out of position, my first test print of a calibration cube came out great!

Now I just need to fix the Kickstarter. I think I've narrowed it down to two issues, bad filament and worn or damaged hobbed bolt. The black filament that wasn't working right on the Kickstarter doesn't work on the R1+ either, where other filament is.

More tests and work to do but with a working printer I can finally have some fun printing the way it's supposed to work.

 

Been printing like a fool on the R1+, so nice to have a working printer! Still working on the kickstarter. I replaced the hobbed bolt and while extruding some PLA while lightly holding the filament as a test, I still felt the extruder 'pull' stop once in a while. I marked the spot on the hobbed bolt where the pressure was light and sure enough it matched the mark on every rotation of the bolt. This seems to point to a bent hobbed bolt, but what are the odds that my old one and new one are both bent?

To make matters worse, I took the screws off the tensioner and took out the bearing that applies pressure to the filament against the hobbed bolt and just wiped it down. I put everything back together and then it started feeding fine. I'm still not sure if I have something out of round or if it has something to do with how things are lined up and how I tighten the spring tension screws. I printed something with PETG and for the most part it printed fine but I saw what might be signs of the extruder slacking off again. I'm still new to PETG, so I need to spend some time printing PLA on it to tell for certain.

It's currently down while I install a cable chain because I was trying to use a couple links printed with the extrusion issue and they snapped when installing. I need to print 2 or 3 more on the R1+ to finish that project and get back to testing.