These two pieces were printedÂ
on the same 3D Printer, it’s the same model, same slicing settings, the very same GCODE file… So why I was getting these BLOBS? Hold on to your seat because, to FIX this problem, I had to turn off a “feature” that comes enabled in most new 3D Printers, including yours! But you can fix it, now, on Geek Detour If you download this model, slice it and save it on an SD Card, your 3D Printer might give youÂ
something terrible like this… or just in some areas… Do you have a guess why it happens? Write your guess in theÂ
comments before we continue… Because, I found just a few videos talking about this particular problem it can happen in printers from any brand and we can change that! The best way to visualiseÂ
it is to print in vase-mode because they should be completely smooth… So I took a picture of this mystery and I posted on a 3D Printing Users Group asking: “Do yo know what is going on here?” And the answers were all over the place… The top guess was: “Its WET filament”. Yeah, humidity in the filament bubblesÂ
up in the nozzle as “water vapour”, but it makes the whole part ugly and our mystery part hasÂ
blobs just around this area then it suddenly gets perfect. And if you look closer: between the blobs the plastic is pristine. Humidity is not the problem. Another guess was: “It is Randomized Seam!” That’s not a stupid guess at all! Because “the seam” makes a very ugly line. And to make the seams less obvious you can randomize its position in every layer. This is the result: indeed you have a bunch of tiny imperfections scattered all around the piece. The difference is that here they are random and in our mystery issue you can see a pattern. Even more important is thatÂ
in VASE MODE there is no seam, the nozzle should make a non-stop spiral from bottom to top, with no seams. So, what are these?! Let me show how these blobs appear when you print: here is a vase mode printing perfectly. The nozzle never stops moving. But look closely now there is something wrong happening: from time to time the nozzle stops briefly, then it continues and stops again… prints a little bit more and stops The print head is stopped but the nozzle continuesÂ
oozing some extra plastic. Each time the printer stops, we get a Blob. So, the problem are the little pauses… ...what is making the printer stop?! If you are an experienced user, you will shout: “- Your model has too many vertices!” “- Vertices? It is round!” “- Precisely!” “- What?” It’s true: STL models are,Â
in fact, made of triangles. Even a cylindrical shape like thisÂ
gets transformed into polygons. You can make it very Low-Poly thatÂ
doesn’t look so rounded anymore. Or you could crank it up, High-Poly, with enough triangles toÂ
make it look really smooth. But quality has a price, of course. On a low-poly version, this “circle”Â
uses just 50, 52 movements per layer… 2 kilobytes of GCODE. But on a high-quality model the same circle is broken down into 150 movements… 6 kilobytes of GCODE for the same layer. The printer needs 3 times more processing power to make the same movement without pauses. So, does it mean there is a limit to how smooth a curve can be printed? Ah, NO!.. Yes! Well… Two years ago, Stefan from CNC Kitchen madeÂ
this EXCELLENT video about Blobs. His solution was to reduce the number of movements so the printer would never stop. When Stefan made that video, the printer he tested had an 8-bit board running Marlin at 20MHz with just ha ha, 16, 16 kilobytes of RAM! 16 kilobytes!... But things changed A LOT… Now, SD Cards are much faster and 3D Printers also got a lot more powerful. Here I am printing on a Neptune 3 that has a 32-bit board running at 84MHz with 96 Kilobytes of RAM. 96 doesn't look much, right? It's... that is... 6 times more! It is so powerful, powerful enough to print my HIGH-POLY model, without ANY simplification, at insane speeds! So, if 32-bit printers can print HIGH-POLY models, at insane speeds, without any hick-ups or blobs… WHAT ON EARTH was happening here???!!! The culprit was the “Power-Off Recovery” feature. "- What?" Yeah! It’s a feature that, if lights go off… when electricity comes back, theÂ
printer just continues printing. That’s a good thing, right? Sure! And it comes activated in most new printers! The fact is: if you disable “power-loss recovery”, you can print a high-qualityÂ
model, at insane speeds! But if “power-loss recovery” is enabled and you print a high-quality model,Â
or print anything fast enough, you get hick-ups and blobs. But the mystery remains: Power-loss recovery!? Why.. How?! The reason is: it also uses the SD Card! [Thunder clap] So, the printer is constantlyÂ
reading commands from the card, getting coordinates to move the motors and print… Every new movement is put on aÂ
buffer, a queue of movements… For a perfect print, specially in vase-mode, this queue should never get “empty” because if it does, the print head stops until more movements are put in the queue. Reading gcode from the SD-Card is fast and the queue normally never gets empty. When you have “Power-loss Recovery” enabled, Marlin periodically saves theÂ
print job state to the SD Card, or Flash Drive, like a “check-point”. These “check-points” are what enables the printer to recover from a power-down… But while it is busy writingÂ
a checkpoint to the SD Card the queue doesn’t get new movements. The queue is not big at all: the default is just 16 segments ahead… When you print something with straight lines, "that" is big enough to keep the nozzle moving through many millimeters, and writing a “checkpoint”Â
doesn’t cause any interruption. But, a super smooth “cylinder” like this can exhaust the queue very shortly. So, there is not enough time for a checkpoint… all the movements are quickly printed, the queue gets empty, the printer stops and we get a Blob. [scream] So, what do we do about it? Where I live, energyÂ
distribution is extremely stable. So, I just DISABLE “Power-loss Recovery”. And there is a nice bonus: with less writes my SD-Cards will last longer. So, there's a way to do Power-lossÂ
Recovery WITHOUT an SD Card I'll talk about in a second But most printers USE the SD Card, and the Neptune 3 didn't comeÂ
with a Menu option to enable or disable Power-loss Recovery... So I prepared two gcode files to do that! I will put a link for them on the description so you can enable or disableÂ
it in your printer too! By the way now on YouTube there is a button where you can buy me a 'Thanks' it supports me to keep making videos. Yeah! There is a better wayÂ
to have “Power-loss Recovery” that doesn’t interfere on the print quality, it writes a “check-point” ONLYÂ
when a real power-cut happens but it needs some hardware changes. If you are the type of personÂ
that likes to modify your printer, Chris, from Chris’s Basement,Â
made an excellent video that I will link in the description. So far, the simplest option isÂ
to disable Power-loss Recovery and, if you care enough,Â
buy an UPS battery backup. SD Cards can also cause blobs… it's true! But it get's very random, not a clear pattern. You should buy a decent Class 10Â
SD-Card from a reliable brand! OctoPrint also causes BLOBs. Also true. It happened toÂ
me years ago and the problem was a LONG USB Cable I was usingÂ
between the Raspberry Pi and my Ender 3. I bought a short, good quality, USBÂ
cable and it never happened again. Have you ever lost a print job
because of a Power Outage? Or did your printer continue printingÂ
just fine after energy came back? I should test it properly… Specially because of theÂ
super long time-lapses I print By the way, you should watch this time-lapse: the camera moves while it prints, I had to create a machineÂ
and software to do that!!! It was insane! I’ll bet you’ll love it!
