1.1.1 Retraction problem?

[wbailey]

I seem to be getting a few blobs of plastic in place of retractions upon updating to 1.1.1. I'm not really familiar enough with gcode to be able to tell whether this is actually because of the update or not but the timing seems suspicious. The blobs don't seem to occur on every retract.

Here is an affected gcode file:

flower_pot0.gcode

1.1.1

(2.82 MiB) Downloaded 632 times

This is what the first layer ends up looking like:
http://imgur.com/mCJCXqA
You can see one blob that I'm pointing to and another in the lower right. I've tried generating this gcode file a couple of times and the blobs seems to move around.
I hope this isn't actually a hardware problem!

[chuck12]

I had the same problem so I don't think it's the hardware. My print head stops momentarily and deposits a nice large blob on my first print I
tried with 1.1.1 going back to 1.1.0, I think.

[Simplify3D]

I have a feeling you won't see any difference between 1.1.0 and 1.1.1. Feel free to look at the G-Code and see for yourself. The G1 E* moves (without X/Y/Z coordinates) are the retraction commands. The G92 E0 command is essentially resetting the counter for how much filament has been extruded. So at the start of each layer you have a G1 E1 (prime 1mm of filament) and then at the end you have another G1 E* command where the filament position is 1mm less than the previous position (meaning that 1mm is retracted back into the nozzle). That's correct and exactly what it should be doing.

Both PLA and ABS have a really bad habit of sticking the the brass nozzles of our extruders. Many times if I see a blob at the start of my print, it's because there was already some plastic hanging on the extruder tip that was just waiting to get deposited. No retraction settings will fix this. What we typically do is preheat our printer using the Machine Control Panel and then extrude 50mm of filament just to make sure any air bubbles are flushed out. Then we wipe the nozzle with a spare toothbrush to get rid of old plastic that's still hanging on. Finally, we start running the build, but we almost always use a few skirt outlines to make sure things are stabilized before the extruder gets to the actual part. It doesn't look like you are using a skirt in your print, so I would highly suggest turning that on. Let the plastic junk attached to your nozzle get detached on the skirt instead of the actual part.

[wbailey]

I'm afraid it is something different with the new version. Here is a video I took of the problem:
http://www.youtube.com/watch?v=SAzCAPfG5d8

The blobs occur when printing the same gcode file with 1.1.0, but not when generating a new gcode file with the same settings and then printing that with 1.1.0.
Now that I think about it, the only difference is that I have G2/G3 commands enabled in 1.1.1 since they were fixed in that version. I suppose this still leaves room for a problem outside of creator, in the M2 firmware's support for those commands. I don't have any other printers to test this idea with, sadly! Also, I have no idea if this problem is actually related to retraction now. I'll try the same print with 1.1.1 and G2/G3 disabled.

Edit:
I just tested it, and the blobs do not occur when switched to radial arc compensation instead of g2/g3 commands

[Simplify3D]

Ah yes, I didn't realize you had G2/G3's on. We've seen the same problem here. The Marlin firmware that ships with the M2's has some pretty bad slowdown when it's doing trig calculations for the G2/G3 commands. I've heard that more recent Marlin revisions are better, but I haven't specifically put the two back-to-back yet. You can use the Previewer to ensure that the G2/G3 commands are coded correctly, but you probably need to update your firmware if you want the firmware to handle them better.

Is anyone using a newer version of Marlin that can confirm if this problem goes away with their latest releases?

[chuck12]

Yes I can confirm the problem on my M2 with the newer firmware. I get the same blobbing with the his test g-code and prints I have sliced with 1.1.1.

[wbailey]

Ah yes, I didn't realize you had G2/G3's on. We've seen the same problem here. The Marlin firmware that ships with the M2's has some pretty bad slowdown when it's doing trig calculations for the G2/G3 commands. I've heard that more recent Marlin revisions are better, but I haven't specifically put the two back-to-back yet. You can use the Previewer to ensure that the G2/G3 commands are coded correctly, but you probably need to update your firmware if you want the firmware to handle them better.

Is anyone using a newer version of Marlin that can confirm if this problem goes away with RC2 and beyond?

According to this https://groups.google.com/forum/?fromgr ... ms7Q0z9giA
the m2 ships with RC2 already. I guess I'll try something newer.

[Simplify3D]

FYI, they've been using the term RC2 for awhile now. The M2 firmware was released in August of last year and the Github for Marlin has been updated many many times beyond that. So maybe I should have said, can someone confirm if this is an issue with the latest version of Marlin.

[Karl_Williams]

I have been using a really old version of Marlin with my Gen6 board so I'll update to the latest version on the weekend and see how it goes.
I gave up on using G2/G3 codes with marlin a while ago because for small circles it would move the extruder to the start of the arc, extrude a point, and then move to the next arc location and do the same thing.
It seems like it might have been the bug described here: https://github.com/ErikZalm/Marlin/issues/127
It looks like the author of the bug report might have added a line to the firmware to fix the problem where he writes," if (segments == 0) segments = 1;"

[bfishler]

I can add a data point here...just experienced the same problem; see attached pictures. I watched it print on the first layer...the nozzle head stopped moving, but i saw it extrude a good amount...then it continued to move. It also happened at random points towards the upper region of the part. I definitely remove all blobs from the nozzle about 1 second before it touches the build plate to avoid any issues, so it wasn't that...

So you're saying the current fix is to uncheck the "replace with G2/G3 commands"? I printed several parts with earlier versions and no such trouble, although I think the G2/G3 was auto unchecked then?

Also... I noticed for most of my prints so far, when I look at the tool path preview I see some odd "cross-hatches" along what should be a perfectly circular section. See the other attached photo...this has shown up in multiple parts/settings/versions...for the particular setup, I was using no infill, 3x layers for the wall, and slicing this "http://www.thingiverse.com/thing:37327".

Just to add in...awesome job with the software so far. Features that I wanted seem to be magically added each release/bugs removed! Now if we could just get the preview/memory error problem resolved/64-bit status...