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How much ooze is normal ooze?  

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aeva
 aeva
(@aeva)
New Member
How much ooze is normal ooze?

Hi everyone,

Long time Reprap enthusiast and recent and proud owner of a Genuine Prusa i3 MK3S+ here.  I acquired aforementioned Mk3S+ new and factory assembled last month and have been printing with it pretty much constantly, and it has held up great so far.  I have 7 different new rolls of Prusament PLA that I've been printing with, and I've been using the recommended settings for everything.  I store the filament in a drybox (large sealed bin w/ an overkill desiccant).

There is one thing that struck me as a little odd, which is that the printer oozes pretty steadily when at temperature.  It isn't enough to cause problems, as I can just pull it away before it the print starts and things are mostly fine, but I've noticed that it tends to not really disconnect from the nozzle, but leaves a very long fine strand of what I've nicknamed "wizard hair" to differentiate from what I think of as normal oozing.  This is the first 1.75mm filament printer I've owned, so maybe this sort of thing is just normal.  Anyways, When printing the parts come out looking great, except that short travel distances outside of perimeters always leave these ultra fine ooze trails.  If I don't design around it, my parts come out covered in gnarly wizard hair that is difficult to remove.

Most of the time the stringing is negligible, like in this print:

If the part is really small, the stringing looks more or less consistent with this picture from the related knowledge base article:
wizard hair

I assume the difference to the hot end hovering around a smaller area for too long which makes the fan somewhat less effective.

So with that in mind, I have this singular question:

1. Is this the normal expected amount of PLA oozing for a brand new factory assembled genuine Prusa i3 MK3S+ using the latest stock configs and official tools and so on?

Thanks,
Aeva

Posted : 28/09/2022 5:52 am
JoanTabb
(@joantabb)
Moderator
RE: How much ooze is normal ooze?

Hi Aeva, 
I would say No.  

the image above is a five colour Multi material unit (MMU) print, as you can see, four of the colours are good, but the silk gold filament is stringing like crazy... 
the filaments are 
Blue - New roll, from '3DQF' a modestly priced UK manufacturer
Black - old roll 'Prusament'
Pink - Old roll, Chinese no name
Gold Silk - Old roll, Chinese no name
Silver Silk-Old roll, Chinese No Name
Silk Filaments tend to be 'Odd' if you extrude them into free space, they seem to shrink in length and increase in thickness they also tend to be a little more stringy... 
the above model started printing at 'Normal' PLA temperatures I noticed the stringing and lowered the temperature to 195C (which is normally enough to combat stringing), and went to bed. obviously 195 was not low enough... 
the next print was Bulbasaur five colour MMU Print, which I printed at 185C, with negligible stringing. 


this print was red PLA, White PLA and Black TPU. 
The white PLA was the worst roll I have ever had for stringing...   I have blasted this print with a hot air gun, but you can still see the remains of the stringing. 

I ended up having to reduce the print temperature to 170C, to sort the white PLA Out. but that brought problems with the Low Temperature Extrusion setting, which is normally 170C...   I ended up dropping the low temperature extrusion setting to 140C, 
If the extruder drops below the low temperature extrusion temperature, it simply stops extruding... and will only start extruding when the temperature raises above the low temperature extrusion temperature...  so it looked like a blockage, but there was no extruder motor ticking... 

I suggest that you try a small test print, with a lower extruder temperature. 
Beware of increasing the retraction length on a direct drive extruder like the Prusa, has... it's likely to lead to heat creep and blockages... 

Regards Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 28/09/2022 8:56 am
aeva liked
fuchsr
(@fuchsr)
Famed Member
RE: How much ooze is normal ooze?

Looks and sounds pretty normal to me. As Joan said, you can try to adjust the temperature down or print a temp tower to minimize stringing. Oozing while getting to temperature is normal, tweezers or needle-nosed pliers will take care of that. There's a bit of stringing in your photo but I'd put it into the "heat gun is your best friend" category, not anything serious (like what you're seeing in Joan's picture).

Posted : 28/09/2022 10:39 am
aeva liked
Diem
 Diem
(@diem)
Famed Member

Both oozing and stringing get worse with damp filament.  Perhaps your drybox isn't enough - try drying some filament.

Cheerio,

Posted : 28/09/2022 7:13 pm
aeva
 aeva
(@aeva)
New Member
Topic starter answered:
RE: How much ooze is normal ooze?

I can say with great confidence that my drybox is overkill, and my house is thoroughly dehumidified.  That and, seeing the oozing from spools freshly extracted from air tight vacuum sealed bags, I think we can safely rule out the filament being moist.

Anyways, this is great information.  It sounds like this is more tweak-the-temperature-and-use-a-heat-gun territory, and not so much a reason to field strip my hot end.

Thanks everyone!

Posted : 29/09/2022 5:03 am
Neophyl
(@neophyl)
Famed Member
RE: How much ooze is normal ooze?

Heat gun is the best, or a butane lighter with a blue flame (which I find easier to use than a heat gun).  

One thing I will add though is that just because the filament is new and came out of a sealed baggie does NOT mean its not got moisture in it.  Manufacturers quality varies and even from the same manufacturer it can vary.  Think of the difference in humidity between summer and winter in a lot of places.  Couple that with when its made and packaged.  I highly doubt that the entire production facilities as well as packing/shipping are all air conditioned for temp and humidity all year round.

Posted : 29/09/2022 6:12 am
Diem
 Diem
(@diem)
Famed Member

I can say with great confidence that my drybox is overkill, and my house is thoroughly dehumidified.  That and, seeing the oozing from spools freshly extracted from air tight vacuum sealed bags, I think we can safely rule out the filament being moist.

OK, definitely try drying some.

Cheerio,

Posted : 29/09/2022 8:03 am
JoanTabb
(@joantabb)
Moderator
RE: How much ooze is normal ooze?

This guy has more time on his hands than me! 
🙂


regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 29/09/2022 10:27 am
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