Hello,
Printing some cookie cutters out of pla. Is this normal looking on the first layer? Looks kind of sloppy.
Looks like over-extrusion. Did you dry and calibrate the filament?
1 Like
The only time I’ve seen output this bad outside of a nozzle failure was when an incorrect filament profile was used. This is what I would expect if someone was let’s say selecting PLA profile for PETG or TPU profile for PLA. I can’t imagine how this outcome could be produced without something being seriously miscalibrated. @EnoTheThracian suggestion is the first thing one should look at.
2 Likes
The filament has been in the closed ams with desiccant installed for about a week. We have a pellet stove running in our house. I ordered a meter to check moisture . At what levels is moisture problematic for PLA?
I always leave the box checked for filament calibration. One thing I noticed is that there still seemed to be a tiny bit of the black PAHT-CF left, even though I ran the “load” process for the PLA basic before sending the print. PLA basic was chosen in the filament section in the slicer. Perhaps I should increase the flushing volume.
The trouble with moisture is twofold. First of all, normal home users can not measure how much is in a filament. Measuring the ambient humidity has no meaning in this context unfortunately. Secondly, even small amounts below 2 promille can cause changes in rheology, i.e. 2g per kg.
But of course you also need to ensure a clean nozzle. Flushing PAHT with PLA is not likely to be entirely successful. Try a few cold pulls with the hex key method.
1 Like
To answer that question; moisture levels are problematic when they interfere with printing. Unfortunately it’s a lot like certain medical diagnosis, some things can only be diagnosed when they show symptoms as did your example.
It’s not your fault but this is a common subject here. There are probably at least 1-2 posts a week on this topic.
The top four misconceptions most often posted about filament moisture:
- “It came from a factory sealed bag”.
- “But I dried it for XX hours…”
- “My house/office is in the desert and I have less than 2% RH” or something like that.
- Filament can dry on it’s own if left in a dry location.
– Correct Answer: Filament must be heated to release moisture.
BTW: Can you guess which one of these test cylinders printed from Bambu Silk PLA that came right out of the sealed bag and which one came later out of the dryer?
____________________________________________________
To answer your question more thoroughly, the only reliable way to determine if a spool has absorbed moisture is to weigh it before and after drying noting that some of the weight can come from the cardboard spool if is not plastic. But to not weigh it is pointless. Too often, bullet point #2 becomes a wasted effort if the presence of moisture is not confirmed first. For example, if the issue stems from something else and we spend hours or days drying the spool without tracking its weight change, we are merely guessing that moisture is the problem when it could be something entirely different.
___________________________________________________
You brought up a significant point: another indicator that moisture has been removed, aside from weight, is monitoring the filament while it’s in the dryer. Moist filament will cause the ambient relative humidity (RH%) to rise as it heats up, eventually leveling off. However, most non-instrument-grade hygrometers only measure down to 10-15% RH. Even if your Dryer or AMS hygrometer reads 15%, the true RH could be lower. It’s important to understand that RH and absolute humidity are different. RH is temperature-dependent, which explains why opening a dryer box can cause RH to plummet. This doesn’t mean fewer water molecules are present or that they’ve vented—it’s likely because the RH calculation has changed due to heat loss in the chamber.
There’s no need to spend excessively on hygrometers; close enough is sufficient for our purposes. However, having multiple independent readings inside a dryer or AMS is a good practice. This will allow you to better understand if your dryer has hotspots.
For day-to-day measurements in my dry boxes, I use standard round or rectangular humidor hygrometers. For higher-temperature monitoring, I recommend reptile hygrometers, which can measure above 70°C and have external sensors. This is important because LCD displays tend to black out at 50°C and can suffer permanent damage over time.
I used both round and rectangular variants in my dry boxes. Why do I choose rectangular over round or vice versa? Price!!! Whichever was cheaper at the time. In bulk, these can be purchased at $2ea and on Amazon, as low as 3 for $9.
These reptile hygrometer/thermometers are the better kind and very helpful since one can locate the probes outside the area being measured. I use these to keep my dryer honest and to be absolutely clear, no dryer I have test has anything close to accurate reading. They can be off by 20%RH.
This is cheaper kind for everyday use.
As you can see, this variant is $1.80 each because its on clearance. This is cheap enough to keep one with every spool. However, the challenge is finding them in Celsius as opposed to Fahrenheit. Often I have to spend a little more just to get the Celsius versions, it’s all market driven.
I’ve read till the end of your post but you didn’t unveil the answer (I personally guess the good one is the one from the dryer but …)
Yes, you are correct. I guess it was my dry sense of humor showing through that had me insinuating the obvious. 
The one on the left was the brand new out-of-the-bag filament. The one on the right was after drying.
If you ever got the chance to witness how filament is made, it’s a wonder it isn’t soaking wet out of the bag.
Here are two unrelated videos on that topic which show “How it’s made”. In each video, the filament has to go through a water bath to cool down after extrusion.
This video at 49s tries to explain what happens to the water. They say they dry it using an airblade(Dyson?) dryer. Clearly, if other’s use this method, it doesn’t always work.
1 Like
Thanks for the explanation Olias, you “wiped” my doubts (you act like a dryer? 
)
Thanks also for the videos, they made me feel that there’s plenty of chance that filament out of the box aren’t dry at all, better to dry them always …
1 Like