Jump to content
Ultimaker Community of 3D Printing Experts
Sign in to follow this  

my prints are now very brittle?

Recommended Posts

ultimaker with v2 hotend and the upgraded feeder.

cura 12 / 13

ultimaker control panel, NO heatbed

it all used to work just fine, now this week it seems to be printing very weak and brittle prints, they seem as if they are laminated. all the settings i previouslyused, no longer seem to work, i used to print with pla at about 215-220 now ive had to try to increase the temp to about 230-235 and seemingly still no success.

the print seems stringy, i initially started the print at all default speeds etc etc.

0.2 layer height and the examples i am showing were at 80% infil, i used the ultipanel to play about with the temperature while printing, but it was at 235 when the pla seemed to be flowing evenly.

earlier i had printed off a similar item to the one in the picture@ 220 degrees and it turned out fine, then i have tried twice to now print out a second piece and it just comes apart as i lift it off the bed. i tried lowering the temp to 200 ish and it comes out very rough in parts ie bumps in it, so on the next layer print the head catches on the bumps. if that makes sense. i had used different pla prior to these larger parts and that was starting to show similar issues.

its the fact the part is so weak in structure, the long belts need a belt tensioner, they are not bad, but they do need a tighten, but i cant even print a belt tesnioner, because they are so brittle. so any idea on what i should be looking for, am i going the wrong way with the heat, should i be lowering it, i am sure i tried a different item, but at a low temp and it was just the same.

any ideas would be appreciated

pictures here

the prints in the pics have been destroyed a little by me as i tried to see what their DNA was like, but in the main you can see the delamination effect


Share this post

Link to post
Share on other sites

I have heard moisture content can have a large affect on PLA thermal characteristics. I have never documented it really, so I can't speak from experience, but perhaps that is what's happening. Your roll arrived nice and dry with a moisture eater inside the packaging, but after sitting out, it has absorbed some moisture and is raising the melt point of your filament? I would say try printing it at the 240? I know many people are afraid of higher temps, but as long as you are maintaining a feed rate and don't have excessive retractions, you should be more than okay at 240.


Share this post

Link to post
Share on other sites

Use what temperature works. I'm printing ABS on mine at 255 degrees. I've heard that as long as you keep it below 260 degrees, you should be safe. As for printing PLA at that high, that is pretty well unheard of. I've printed PLA from 192 to 225. It may well be something with the material and less with the printer.


Share this post

Link to post
Share on other sites

Hi Intensewalkera

It looks like you're under extruding by a fair bit which would be giving the delaminating problems. I doubt it is temperature though if you used to print at that temperature.

Unless your E steps per mm has changed you may have a blockage (possibly a plug or clogged nozzle) or your extruder is not pushing enough filament due to lack of grip on the filament or other cause.

Check and see if you get reasonably deep marks imprinted on the filament, if not you may need to adjust it or clean the bolt.

Check if you are squashing the filament into an oval shape in the extruder, which makes it hard to push through.

For the blockage turn the temp up very high and push some filament through by hand for a bit.

Otherwise you could take the bowden tube off at the heater end to see if there is a gap or plug there. I like to do this step last as it's preferable not to take it apart here if you don't have to.


Share this post

Link to post
Share on other sites

Consider lowering your fan - did you change fan settings recently? Is the fan cooling the tip too much?

I print PLA at 240C all the time. I know I'm weird but it works well for me. Don't be afraid to do some test cubes or something at even higher temps.

Owen may be onto the actual problem - possibly some blockage.

Did you recently start printing faster? Faster speeds might need higher temps. Look at your fan shroud - did it break? Or get ripped open? Is the air suddenly on the tip? Did you recently change fan settings? Maybe your new filament just needs to print at 250C. Or at least 240C. Experiment. Maybe the new filament is larger than 3mm in diameter in spots and gets stuck in the tube (which is not much larger than 3mm and sometimes the filament can't fit through the bowden tube - especially when compressed by the feeder).


Share this post

Link to post
Share on other sites

thanks for the replies - i can fill in a few of the blank details, i had already tried and looked at a few things on my ultimachine.

one day i printed a 5 hour part with my usual settings, came out just fine.

the following day i come to print the opposite handed piece, with identical everything, setting, same PLA, same Cura etc.

twice on the bounce i tried it with the same de-lamination.

i had looked at the e-stepper, as i thought i may have messed this up when using the ultimaker panel, this was 836, which is inline with alot of people with the extruder upgrade.

i can turn the extruder by hand easily and filament feeds fine and extrudes fine, even at my normal temp of circa 220. i am unsure of what pressure to use on the extruder spring, it had been fairly tight, i backed that off for my second failed print,i can see the knurled marks on the pla as it moves throught the pipe. so i even though its not perfect, i dont think this is causing my problems, if i hold my fingers on the pla going in, i can feel it moving through smoothly. i will check the pla shape tonight. i did measure its diameter and it was a consistent 2.82mm.

i dont think the head is clogged, i will heat up the head and let some push through, but i have sort of done that already.

the cooling fan is an interesting area, since i blew my darlington transistor a while back and since them the fan has always been on (new part ordered) but i have printed many parts with the fan like this. the fan head looks fine - not interferring with the nozzle temp.

now then PLA itself, this is an older reel , maybe 5 months old, it had no silica bag in it to remove moisture, (i have 6 of these reels!!) it was stored in the loft / attic, i have read on the moisture content before, because alot of my reels tend to go off* toward the end of the reel if i dont use them up fast enough. i have heard people put themin the oven to dry them out too, i think i will wait for my wife to be in another country before i dare do that!

i will go for an ever higher temp print, the last one was 235 degrees :-|.

the only thing i did different when preparing this print, was normally i set the temp of the ultimaker, on the control panel.

for this one i set the temp in cura (i had been leaving that on 0 because i used to get the error of mintemp on the controller) but i had upgraded to cura 13 to try fix my brittle printing error and i noticed the mintemp error had gone in this version.


Share this post

Link to post
Share on other sites

I had a reel of that silver/grey PLA.

I had to throw it away when it was 80% used because it was too brittle (before printing). It was so brittle

that it snapped inside the bowden tube when it was forced to curve.

I would suggest trying some other PLA reels before you start worrying about changing printing temps and so on.

From your pics I dont think its a printing issue. But its hard to tell without having a real part in hand to look at closely.



Share this post

Link to post
Share on other sites

Update, I tried printing at circa 240' same problems, I changed out the PLA for another reel , but from the same supplier and same age as the failing silver one, initially it looked good and I let it print for quite sometime, circa 220 degrees, but half was through I could see it was looking brittle again, so I stopped it and sure enough it was just like the other failed prints, very stringy looking and hence a weak print, it even breaks as I peel it off the bed. I printed some smaller parts, belt tensioner s but they too are so stringy and brittle, even though there does seem to be a good amount of PLA being extruded. All the settings looked ok, it seemed to feed ok, seems to melt ok, I am at a loss. I will try some old off cut PLA I have, from a different supply, it's very frustrating, more so because it worked fine with identical everything , the night before. I don't fancy the task of, or think it is the hot end blocked, but I guess I should take it apart so I can rule it out.

Share this post

Link to post
Share on other sites

i should of said, a different colour too!

i ran a few tests again, with the new colour PLA, same results really.

i calibrated the 100MM extruding check, mine was circa 102mm.

i did back the spring, right off, on the extruding wheel upgrade. it did seem to be grinding up

the new red PLA.

it makes sense that it is underextruding, when the print first starts, it looks fine. the best part of the print is the

apron! then it gets progressively worse, which would tie in with the pre-melted pla in the head running low.

sadly i think i will have to take the head apart, can you tell i am not too keen on doing that! ugh.

its never been apart since i have made it, so i guess now is a good time to see how its all looking in there.

i will try one more print with the extruder upgrade spring backed off, fingers crossed for that small spring.


If its the same age, and supplier I would expect the same result. It all probably got wound on the same day....

Best not to stock up on loads of reels unless you print every day.



Share this post

Link to post
Share on other sites

Fixed !!!!

ok i lied a bit in my initial details, i have the hotend V1, i thought the latest one was V3 and hence i thought mine was v2.

Anyway i stripped the hotend down, never been done since day one of my ownership and i have never had a need too either. it wasnt as much of a hassle as i had thought it would be. there in the peek is about a 1 - 2mm plug of PLA,

it looks very insignificant on its own, but i recheck the head install instruction which asks for 8mm of bowden tube to be sticking out, mine was circa 6mm and the bowden had bite* marks on the outside as if it had been dragged through the holder. SO i guess over time its worked its way loose. with hindsight my prints have got progressively worse, but its been such a slow process that i have never noticed.

when i assembled it all and did my first test print, the difference was like naight and day, the pla was comparatively gushing out. :-\ this was the PLA that refused to work last time.

i did a few small belt tensioner parts as a test and they worked out well. when i repaired my hotend, i had a spare new one, so i used that rather than mess about with the old one, what i did notice was the old nozzle was about 1.5mm shorter!

the end had worn away over time, so the hole was bigger too. i know in the early months , i had a number of times that my nozzle hit things that it should not of, so over time its really worn out, its worth renewing this once in a while.

anyway my failed printing cost me 248 euros !!!

i ordered the proper V2 hotend, but postage was something rediculus like 22 euro, but that must go on weight and size, so i added more and more to see what weight would increase the postage, nothing seemed to.

so a V2 hotend, knurled drive upgrade,belts pack and 4 lots of flexible pla later !!


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Our picks

    • Ultimaker Cura | a new interface
      We're not only trying to always make Ultimaker Cura better with the usual new features and improvements we build, but we're also trying to make it more pleasant to operate. The interface was the focus for the upcoming release, from which we would already like to present you the first glance. 
        • Like
      • 114 replies
    • "Back To The Future" using Generative Design & Investment Casting
      Designing for light-weight parts is becoming more important, and I’m a firm believer in the need to produce lighter weight, less over-engineered parts for the future. This is for sustainability reasons because we need to be using less raw materials and, in things like transportation, it impacts the energy usage of the product during it’s service life.
        • Like
      • 12 replies

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!