Daid, the 14.06.2 fw is still very broken in that it grinds the filament in every started print. We tried it at least two times and then we had to revert to Simons patch.
I think if you include the patches that relates to the two comments Simon stated here above we should have a well working release...
As far as I can tell, 14.06.2 does include Simon's updates. The merge is at https://github.com/Ultimaker/Ultimaker2Marlin/commit/46b55a2fe99833a3e3034431d3b920f08210ac7d, though there were a couple of tweaks after the merge, and it's possible that a regression may be emanating from one of those.
I'm swamped this week, otherwise I'd try building before and after e54f814' and see if that narrows it down. It looks like there may be a unit inconsistency there.
Steve
The two follow up commits broke the 20mm retraction at the end of a print, and the slower priming extrusion.
Hi again,
So it was printing fine for a while after the firmware update, but then I came across it again.
I destroyed my fan shroud on my UM1 so I tried to print a new one on the UM2.
It looks like this:
Here's 4 fails in a row:
So from left to right here's what I tried:
1. First fail (Cura 14.06 | 0.2mm layer | 20% infil | 0.3mm first layer)
2. Second try same settings (thought it was a fluke)
3. Disabled retraction | 25% infil | 0mm first layer
4. Disabled retraction, tightened extruder tension screw, 50% speed
I'm now printing on Cura 14.03 | 0.2mm/layer | played with the tension screw a bit
And it seems to be printing fine now. I'm not sure if it's the tension screw or Cura, but Cura 14.03 seems to be doing a whole lot better. the top layers are even filled in nicely.
All with the custom firmware.
In each under extrusion case, it was filament grinding.
Not sure if this helps solving the issues... but there you have it.
The two follow up commits broke the 20mm retraction at the end of a print, and the slower priming extrusion.
This patch?
https://github.com/Ultimaker/Ultimaker2Marlin/commit/e54f8145217ca538449302c1e2834e69ccf66cb5
What I did here makes sense, as what the code was doing didn't make sense at all, it's multiplying a speed with a material volume factor...
Is it recommended to level the bed again after installing the updated cura & firmware?
I was affected by the bed level issue and i had to relevel the bed after the new firmware. I think it's most likely that the leveling issue was also present during the leveling wizard.
No it works perfectly and all my first layers are very good
This patch?https://github.com/Ultimaker/Ultimaker2Marlin/commit/e54f8145217ca538449302c1e2834e69ccf66cb5
What I did here makes sense, as what the code was doing didn't make sense at all, it's multiplying a speed with a material volume factor...
Because the speed and the amount were both defined in cubic mm. The volume factor converts between linear mm of filament and volume of filament. The function being called expects a speed in linear mm of filament/sec.
The constant is defined to be 7, iirc (I'm not in front of the code). I want to prime at 7 cubic mm per second. Because that's in the range the head can handle. By taking out the volume adjustment (which multiplies the constant by about 1/6.5), you're feeding the filament into an already primed head at 7mm/s. That's about 45mm^3 per second. The head can't handle that. And with the new weaker springs, it's not guaranteed that the extruder motor will slip back. In a lot of cases, it just grinds.
I finally got around to trying the latest firmware (the one included in 14.06.1 from the 16th). My printer could handle the priming without problems but that could be because I like to print fairly hot, 235C, and I use my alternative extruder.
I can absolutely see why some printers could have problems with it though, that's a lot of plastic in a short amount of time being squirted out.
I also noticed that the amounts are different if you start a new print after another has finished and when starting a new print after aborting a print. After an abort the amount of priming is significantly smaller. Or perhaps the amount of retraction post print and post abort differs (I didn't time how long the priming was as I didn't expect it to be different).
I also noticed that the amounts are different if you start a new print after another has finished and when starting a new print after aborting a print. After an abort the amount of priming is significantly smaller. Or perhaps the amount of retraction post print and post abort differs
I agree. I'm using 14.06RC6 on Mac.
I've finally become used to manually priming before every print, whether the previous one was aborted or completed: I extrude until filament comes out (usually around 20mm) and then retract 8mm or so. That seems to produce a decent start on the skirt without creating a blob.
The standard retraction after and extrusion before a print simply cannot be trusted to start a print cleanly. Still.
The difference after a print finishes normally compared to when you abort a print is because when you abort, the filament gets retracted 20mm. When you end a print normally it doesn't. It should, and in my version of the firmware, it does.
In the latest latest release firmware (which you don't have, Rick, if you're using firmware from 14.06RC-something), the priming at the start of the print happens in two phases. First, a fast movement, to undo the 20mm retraction, and then what was supposed to be a slower true priming.
However, two things got unfixed compared to the code I submitted. Firstly, the 20mm retraction at the end of the normal print doesn't happen - so there's an attempt to extrude 20mm of filament pretty fast - which can cause stripping on newer-model printers that have weaker springs. On older printers, it just leads to skipping usually. And then Daid changed the speed of the slower true priming, so it actually now happens super fast, kinda defeating the point, and leading to yet more stripping.
Daid, in the light of Simons explanations can you include his patches in a new release?
The 14.06.2 fw still grinds in most cases/machines but simons code works flawlessly...
Thanks
Oops - actually I'm using Simon's code with patches, but the net is the same. On my machine with the patched 14.06etc., it doesn't actually start extruding until several inches of skirt have been traced, whether it is after an Abort or successful completion.
The manual prime method Always works, so I'll continue to do it...
Because the speed and the amount were both defined in cubic mm. The volume factor converts between linear mm of filament and volume of filament. The function being called expects a speed in linear mm of filament/sec.
The constant is defined to be 7, iirc (I'm not in front of the code). I want to prime at 7 cubic mm per second. Because that's in the range the head can handle. By taking out the volume adjustment (which multiplies the constant by about 1/6.5), you're feeding the filament into an already primed head at 7mm/s. That's about 45mm^3 per second. The head can't handle that. And with the new weaker springs, it's not guaranteed that the extruder motor will slip back. In a lot of cases, it just grinds.
AHHHHH, ok.
That's confusing, as all other values are in mm/s. Going to patch it back, and add more comments to remind myself of this.
Looking forward to the patch as my UM2 is being a right princess with the new firmware, sods law after I had almost dialed it in on the older version lol.
I was poking about the net this morning and i found this that made me laugh:
I thought it was fitting 
AHHHHH, ok.
That's confusing, as all other values are in mm/s. Going to patch it back, and add more comments to remind myself of this.
Ahum. Told you so. More comments = good 
Hey guys, just wanted to say thanks for the new start-up procedure. Now I can start a print and walk away and don't need to anxiously grab loose filament strands that might get in the way of the first layer.
Still getting crappy prints, but that's another problem and not firmware related.
Lol. I wholeheartedly agree about the value of comments. But, in my defense, the constant in question is called PRIMING_MM3_PER_SEC, and in configuration.h it's defined thusly:
#define PRIMING_MM3 30 // number of mm^3 of plastic to extrude when priming
// (Ultimaker 2 hot end capacity is approx 80 mm^3)
#define PRIMING_MM3_PER_SEC 5 // Rate at which to prime head (in mm^3/s)
// (Ultimaker 2 upper limit is 8-10)
I made the conscious decision to define these things in mm³/s, precisely because these are factors that are solely related to pushing plastic through the head, and the limiting factor is related to, and understood in terms of, the total volume of plastic per second. A speed of a few mm/s doesn't sound like much when we're used to moving all the other axes at speeds that are 10's of mm/s. But we need to remember that in normal use, the filament typically moves at 1mm/s or less.
Having tested it, I don't think that 30mm³/s is quite enough. By all means increase that to 50 or so.
#define PRIMING_MM3 30 // number of mm^3 of plastic to extrude when priming
// (Ultimaker 2 hot end capacity is approx 80 mm^3)
#define PRIMING_MM3_PER_SEC 5 // Rate at which to prime head (in mm^3/s)
// (Ultimaker 2 upper limit is 8-10)
Having tested it, I don't think that 30mm³/s is quite enough. By all means increase that to 50 or so.
Danger, danger, Will Robinson. :wink: Simon, you mean increase the 30 mm3 priming volume to about 50 mm3? The "/s" there was a typo, right?
(Every once in a while I threaten to design a programming language which is unit-aware. Require units at variable declaration and then refuse to compile if math results don't preserve them...) :wacko:
Haha, yeah. I mean 30mm³ volume. Not speed. Thanks for catching that.
Is there a new firmware patch to fix the filament diarrhea pre print (if so could someone be kind enough to link it) or do I have to sift through the code and fix it myself ..... its been a long time since I've messed with code, and I don't want to break anything.
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Depends if you where effected by the leveling issues. If you where having issues, you might want to level it again.
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