OMG what happened to my PLA

[flackmonkey]

I bought white PLA from matterhackers.com (not pro version) on Aug 2, 2013.  Gradually this started happening to the filament (see attached).  This has progressively gotten worse over the last 2 month and is now completely ruined.  I used about 1/3 the roll without issue. When not in use I store the PLA in my office cabinet in a 1 gallon ziplock with the original desiccant that the pla came with in the bag. 

As this started happening I was thinking that the original spool that it came with, with a tiny center hub, was an issue so I re-spooled the entire thing on a spool with a larger hub.

Can anyone explain what is happening here and how to prevent it in the future?

Also is this something that has happened to anyone else with matterhacker filament?  I have been generally happy with several other rolls of filament and this has not happened on the other rolls.

[Jetguy]

ALL PLA can do this regardless of brand.
Some think it happens with moisture and this is why small diameter spools are such a problem

Again, PLA tend to get brittle with air exposure and absorbed moisture.
Second part is that when it becomes brittle, small diameter spools are KNOWN to cause breaks and thus can lead to an air print.

This was kind of the motivation behind using devices with P-stop to detect out of filament conditions when it breaks like this.

[Dan Newman]

On 12/06/2014, 11:33 AM, Jetguy wrote:
> ALL PLA can do this regardless of brand.
> Some think it happens with moisture and this is why small diameter spools
> are such a problem
>
> Again, PLA tend to get brittle with air exposure and absorbed moisture.
> Second part is that when it becomes brittle, small diameter spools are
> KNOWN to cause breaks and thus can lead to an air print.

Or, trying to change the bend radius by putting it onto a larger diameter spool
core can cause this (when the PLA has become brittle). HOWEVER, had you not done
that first, then it probably would have broken in your extruder feed path. So,
annoying as this is, it might have been breaking somewhere in your extruder with
some chance of requiring disassembly to get any broken bits out.

Dan

[Joseph Chiu]

I've seen this happen to varying extent with PLA, including some of the PLA that we sell -- but you have a particularly nasty case of it!

PLA, being crystalline and brittle, does not like to bend much.  The degree of crystallization varies for reasons which I don't fully understand; and the process of crystallizing induces some dimensional changes as well based on the papers I have read.  Anyway, the net effect is that if you "unbend" PLA from the spool that it is on, the geometry change introduces strain that can lead to cracks which can then propagate -- and hence the shattering.

Generally, you should avoid respooling PLA filament -- and try to choose a filament path that minimizes bending the filament opposite to its natural curl.  Generally, the more straightened the filament on the way to the printer, the more likely it might break.

If you get a couple breaks in the spool, I'm afraid that may just be the way things go with PLA.  If you have a particular bad roll, though, you should contact your vendor to get it replaced.

--
You received this message because you are subscribed to the Google Groups "MakerBot Operators" group.
To unsubscribe from this group and stop receiving emails from it, send an email to makerbot+u...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Stan Velijev]

Funny enough, I was cleaning out my PLA bins today and found some very old PLA at the bottom that was just crushed to bits.

The PLA that broke was all from before the time I stored my PLA in sealed bins with desiccant. My bet's on moisture.

I use a good deal of MH filament, none of it has done this. Just try and keep it cry and sealed and this shouldn't happen.

[Ryan Carlyle]

1) Ziplocks are surprisingly permeable to moisture. Recently I've been doing tests with indicator desiccant and humidity sensors and every ziplock will EVENTUALLY reach 40% RH (same as the air in my home). All the bag does is slow down moisture contamination -- it doesn't stop it. The quantity of desiccant used simply determines how long it takes for the humidity to rise to a point where the bag is no longer doing any good.

2) The desiccant shipped with the filament should be considered exhausted at the moment you open the package. It ALREADY absorbed all the moisture out of the air sealed in the shipping bag, and it ALREADY absorbed much of the moisture that was in the filament itself when it was packed. You should replace it after opening the shipping package.

3) Moist filament will overload your desiccant packet. Given that filament can very easily absorb >1% of its weight in moisture, that's perhaps 10 grams of water that you're expecting a desiccant packet to absorb. Silica desiccant can absorb ~40% of it's weight in water under ideal conditions. So if you seal a puny little 10g packet with a kilo of plastic that has been soaking up humidity on the back of your printer for weeks, the math just doesn't work out. Your filament might be a little dryer, but it WON'T be "dry."

All this means if you use ziplocks, you need to use fresh or freshly-regenerated desiccant EVERY time you seal the bag or it won't accomplish much. Yes, it's a pain. Yes, it gets expensive if you overpay for a ton of little packets. Buy in bulk and learn how to properly bake the moisture out. Or build a proper drybox. Or throw away old filament. Your call!

[Scott D]

I use this 333 Eva dry in a Stanley waterproof tool box that holds 7 rolls and the tray for all my tools. I was using a smaller desiccant metal box with about 40 grams but the beads changed color after 2 weeks and I dint want to have to recharge it every 2 weeks. I bought 2 of the Eva drys so while one is recharging the other is out in the toolbox.

I figure it's worth the investment for things like this then to ruin almost $300 worth of different filaments and colors I have. Small investment to save material and money going forward.

Eva Dry 333
http://www.amazon.com/gp/product/B000H0XFCS/ref=gno_cart_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Stanley waterproof 28 inch toolbox
http://www.amazon.com/Stanley-028001L-28-Inch-Structural-Toolbox/dp/B000KN470Q/ref=sr_1_1?ie=UTF8&qid=1402644432&sr=8-1&keywords=toolbox+waterproof

Scott

[flackmonkey]

Thanks guys for the info.  Its time to protect my investment in PLA better.

The Eva Dry 333 looks like an interesting solution. thanks Scott.

Anyone know if just simply storing PLA in a low humidity environment if it will release any moisture it has absorbed?  My guess is that it will but it may be extremely slow.  I saw some other post on drying techniques but they all look someway messy and potentially difficult to achieve.

[Brandon Andrzejewski]

Hi All,

Has anyone had issues with wet HIPS?  I am content with my ABS storage, and I typically swap rolls often enough that I do not worry about moisture while they are on the back of the machine.  However my roll of HIPS is rarely ever in storage because ~80% of my dual extrusion uses HIPS.    I have not had any issues with it, but it isn't a big deal to keep it with my other filament until needed if it has the potential to absorb significant amounts of moisture.  

In theory I should keep it dry since there are few plastics that are immune to moisture absorption, but the bot looks much better balanced with the left extruder loaded. =P

[Ryan Carlyle]

Flackmonkey -- Yes, it will slowly absorb moisture out of the PLA, but it might be REALLY slow. Not sure how long it will take. Heat speeds up the process but you have to be gentle with PLA and heat. 

Brandon, yes HIPS should perform similar to ABS when moist, but if you use it a lot you probably don't need to worry since the outside few wraps are getting extruded before they can go bad.

[Scott D]

The waterproof toolbox and Eva 333 seems to be a good fit.
I recently purchased the most accurate small hygrometer I could find to measure the humidity in the box. With august approaching and being the most humid month were I love I wanted to make sure it was working. Unfortunately is only measures down to 20%, but I think it's lower than 20%. That's the limit on the hygrometer I purchased. But I know with the AC on my house is sitting around 55% according to the same unit! I kept it out for a day before putting it in the tool box.

http://www.amazon.com/gp/product/B00JXOKS2E/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

[lassi kinnunen]

that looks like exactly what happened to one roll of PLA I had last year.    I stored a damp towel over it for couple of days and boom brittle city for half of it at least..  maybe youre dry storage wasn't a drying storage.

-lassi

[Joe Brunson]

I ordered the toolbox and two Eva-Dry E-500 units, Nice units, I live in South Carolina and the humidity worse every week about now. Haven't printed any PLA yet, going to try some of the new Polymakr PLA, hoping to avoid some of the cracking of large ABS prints.

[Scott D]

You may want to make sure you are able to recharge the Eva-500. From the reviews some people were not able to recharge it. I think if your trying to recharge in a non air conditioned place then the humidity may be to hight for the heating element to be affective. Seems like they used the same heating element in the 333 and the 500. This is why I decided to go with a couple 333 instead. I out them in the box a week apart so one is still in the box and good while the other is recharging.

I would recommend testing the 500 maybe by leaving out of the toolbox to change the color of the beads in a shorter time then recharge it to make sure it works for your environment before the return policy runs out. Giving you time to swap them if needed.

I bought a different meter that starts at 0% now and calibrated using the digital one that I know was already calibrated and accurate. I just checked mine today, and it's averaging about 5% humidity. This picture was taken when it was at 8%. I need to move my tools to another spot so I don't open and shut the box as often. August is the worst month in ohio for humidity and we have had 5 days out if the week raining.
I'm happy with this combination set up so far.

[flackmonkey]

Thanks guys.  I ended up taking all you advice.  I also setup a remote monitor of the humidity.  Check it out on my blog:

http://www.3dprintmd.com/print/web-enabled-temperature-and-humidity-using-spark-core/

[Scott D]

Nice setup. I like the USB battery. I have 2 of them from the same company @ 10,000 mA.
I wonder how long it will run.

[flackmonkey]

The maximum power consumption of the spark core is 300mAh.  That puts it at a minimum of 23.33333hours, worst case.  The actual consumption is probably more like 100mAh which is 70hrs.  I charged the battery to full just before setting it up so that I can get an accurate guesstimate on how long I can expect it to last.  I will let you know.

[flackmonkey]

I have my answer:  slightly over 46hrs.  Not as much as I would have liked but there are a bunch of things I can do differently to decrease the consumption.  Right now its setup to pull data.  It would be much better to push the data from the sensor.  That way the spark core can go to sleep until its time to wake up an push the data.  I will continue to experiment and let you know.