bad problem of shrinkage

[Edel 5]

Hi,

frist i dont know if shrinkage is the correct english word, but i hope so, because warping is something complete different.

The Problem is this

left with shrinkage right is ok

or here maybe you see it better what i mean

I did not had this problem when it was summer, but also the printer is i a heated room.

I ordert now a door, which covers the front, but the problem is still there....

The strange is, that my layout for this part is:

and only the 2 part in the front have this shrinkage, not the 2 at the back...

Now with the door the same, no impovement...

How can i fix this? i dont want to throw 50% part away :(

[cloakfiend 995]

just use support or make your walls thicker. Not sure how long youve been doing this but it takes some getting used to. Heat plays a great part in all things FDM with zero internal structure due to the near melting points and situations of heat. Even months after the print.

Look at the base of a hollow model I printed many months ago, this was because i had it above my mantle piece over hanging my fireplace. Its gets warm, and i guess over sustained time the trapped air inside has expanded and pushed the warmed pla out. if you want it to be stronger, you have to print it stronger. The rest of the model is fine, but the heat from the wooden shelf it was on warmed the base too much and voila! you must have the opposite. the air inside cooled too much, most likely during the time directly after printing.

Edited November 6, 2016 by Guest

[Edel 5]

All where great in summer month, now its not cold in the room, its headet, but walls are ok.

hope to get answer and help here...

[Edel 5]

just use support or make your walls thicker. Not sure how long youve been doing this but it takes some getting used to. Heat plays a great part in all things FDM with zero internal structure due to the near melting points and situations of heat. Even months after the print.

Look at the base of a hollow model I printed many months ago, this was because i had it above my mantle piece over hanging my fireplace. Its gets warm, and i guess over sustained time the trapped air inside has expanded and pushed the warmed pla out. if you want it to be stronger, you have to print it stronger. The rest of the model is fine, but the heat from the wooden shelf it was on warmed the base too much and voila! you must have the opposite. the air inside cooled too much, most likely during the time directly after printing.

 

is shrinkage the correct english word for this effect on my photo or what would you say?

[cloakfiend 995]

shrinkage seems ok. but i get elephant feet on the tops? i got to be honest but i use the same setting for everything and get ok results. if something doesnt work, i do something else, lol. Problem solved!

[gr5 2,173]

Are you printing PLA? This is common with PLA. Lower the print bed by 5C and it should improve. Maybe lower even further to get it perfect. More info here (5th photo down on left - "cave in"):

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide

The basic problem is that the part is too hot and soft and that PLA shrinks as it cools the first few milliseconds so it is almost instantly like snot - like a liquid rubber band. It is still liquid and at the same time pulling so outer corners or outer curves get pulled inwards.

but as you get farther from the heated bed it's fine again.

For PLA 60C is about perfect for heated bed but the adhesion is great all the way down to around 45C.

For other materials such as nylon you can have this same problem but the glass temperature or softening temperature is much higher. Basically no matter what material you are printing - lower the bed temp by 5C to 10C.

[Edel 5]

Yes Pla, and no its not normal, i m printing since spring this year, complete summer, no problems...

the room had in summer a temperatur auf approx 22-24°C...

now in winter its heated, but with 18-20...

But the Bed ist still running with 62°C, because otherwise i had warping and the corners did not had a contact with the bed!!!

OK i will do a test with 45C Bed temp!!! today

BUT!!! this all makes no sence, why the back parts are great, and the front and middle parts are bad

[gr5 2,173]

Maybe there is convection. The bed air is heated and rises and cooler air enters the front so it's cooler near the front of the printer. Ooops - this is backwards from what you see. I don't know but temperature varies a bit depending on where on the bed you are. Within 3cm of the edges the glass is maybe 10C cooler.

Well try lowering 62C to 55C before you go all the way to 45C.

If your parts are not sticking at lower temperatures, then squish the bottom layer into the glass more. Don't do the leveling procedure - instead just turn the 3 screws 1/3 rotation counter clockwise to move the glass 0.166mm closer to the nozzle. If you turn all 3 screws the same amount you don't have to redo the levling procedure.

[gr5 2,173]

So what did you learn @Edel?

[geert_2 557]

In addition to the tips above from cloakfiend and GR5, if the models are small, you could also try printing them with 100% infill.

For better bed adhesion, you could also try the "salt method": gently wipe the glass plate with a tissue moistened with salt water, prior to printing. In my experience this greatly improves bonding of PLA to the bare glass. (It does not work for ABS, and I don't know yet for other materials.) See the full PDF-manual on this salt method at:https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

[Edel 5]

So what did you learn @Edel?

that your trick worked very fine the hole year no problem.

i print with 205 and bed 55.......

all good

but now i have the some problem again with a big part...

but i still print in this improve temperaturs, we or better you gave me...

so what now? reduce bed to 50? and print temperature to 202?

does more infill of 20 to 25% help? or is infill not importent for this problem?

its a nightmare, cause the print took 2 day :(

[Edel 5]

 

[gr5 2,173]

Strange.  Yes, go cooler on the bed.  Print walls 2 layers thick (e.g. shell 0.8mm and line width .4mm) so that the inner wall helps hold the outer wall as it is being laid down.

Fan is important - are you using 100% fan by the 4th layer?

You can go to 40C on the bed I think.  Just beware the part may lift off the bed if you go too cold.  You could even switch to blue tape washed with isopropyl alcohol (never use blue tape without washing with alcohol). With blue tape you can turn off the bed completely.

You can also drop the bed temp by 10C as soon as the first layer is done.

The heat has 3 purposes - if it's above the glass temp of 55C then the PLA is more flexible so that warping forces from above don't pull the part off the bed.  But you are below that so you aren't using that purpose.

The second purpose is allow the filament to flow better into micro cracks in the glass or at least flow onto the glass well.  The temperature needed for this is around 35 to 45C.  Cooler than 35C and parts barely stick at all.

The third thing is to not change the temperature much after you start because the plastic shrinks much more than the glass so you increase stresses and the part might pop off.  But 10C drop in temperature should be safe.

So you could start the print at 45C bed temp and then lower to 35C as soon as the first layer is done.

Edited November 13, 2017 by Guest

[Edel 5]

The printer is standing in a heated room in an old brick building.

Whenever I look at the thermometer, it is about 16-17 degrees in the room.

The only thing I think is that now the nights have minus temperatures and so maybe it's sagging in the room (only at night).

It's really weird that the problem was not 1 year old and is coming back almost at the same time.

i use every time 3x wall, so 1,2mm!

Yes 100% Fan.

You can also drop the bed temp by 10C as soon as the first layer is done.

how can i do that is there in cura 2 a option that it do it automatic?

[Edel 5]

ok the 45h print is over....

i change:

Nozzeltemp 205 to 203

Bed 55 to 50

Infill 20 to 28

Walls are still 1,2mm

so no shrinkage , all sides are good!

But now i have warping :( i had this problem with 55 not :(

[gr5 2,173]

What do you mean by "warping"? Do you mean the edge lifts off the glass? You should call that lifting because there are many things that people call "warping" and I get confused by all of them.

I'm guessing colder air temperatures are somehow causing this (or lower humidity?) but I don't know why that would cause this issue. I would put a cover on the front of the printer - try just some plastic and blue tape. To see if that helps and go back up to 55C.

To get parts to stick like hell here are all the techniques and how to do them well:

 

[Edel 5]

all the years the same problem, and i dont understand, why it comes......

 

i switched now to cure 4 and what did i get?!?! the same problem, i m wondering, why nobody else is writing about such a problem.... :(

 

 

i went down with the bed,,,, increse the print speed a bid, and get more infill in it, we will see...

 

but no idea why

[Edel 5]

[geert_2 557]

In my experience:

 

- If bed temp is too low: the model is very stiff, and the model-edges generally do not lift much, but the whole model may suddenly pop-off the glass, due to insufficient bonding.

- If bed temp is too high: the bottom of the model stays too soft, so the edges may lift due to shrinkage forces acting upon the higher layers, and the whole model may gradually peel off the glass.

- Walls too thin: walls are pulled inwards (similar to the effect you see), and the models tends to lift at the edges and gradually come off the glass. It is like a cardboard box that you fold inwards.

- Not enough infill: walls may be unstable and sag if printed rather hot, and if the bed is rather hot.

- Models with high infill (70...100%) rarely deform, althoug they may lift edges if the bed is too hot.

- Very small models need an extra "dummy cooling block" next to them, so the print head is moved away for some time, so this small part gets time to cool and solidify.

 

I needed to find a balance where the bed temp is high enough to make the model bond well, but not so high that it deforms, sags, or peels off. The optimal bed temperatures differ from material to material: for PLA it is 60°C, for PET it is 90°C in my system. But this could be different for your printer and materials of course.

 

Thin-walled objects with sharp corners and no infill, need a brim. This could be the standard brim, or a custom designed brim in CAD, depending on the model (sometimes only one little area needs a brim). Otherwise I get the effect you see.

 

Models with high infill, generally need no brim for me.

 

I am not sure that these are the effects you see in your models, but it could be.

 

Have a look at this: the dummy cube (green, top-right) needs a brim because it is hollow at the bottom. Otherwise the walls tend to bend inwards and it tends to come off the glass. The supports (pink and orange) also need a brim because they are very small, only a few millimeters, and they have long overhangs which tend to curl up, making the nozzle bang into these curls and knock the part off. The rest prints perfectly fine without brim. All have 100% infill (except the hollow text and ruler, and the dummy cube). For reference: text caps-heigt = 3.5mm, and its legs are 0.5mm. The green dummy block is to provide enough cooling time for the top-section of the yellow part, otherwise these top layers do not solidify. This prints well in both PET and PLA.

 

 

 

[gr5 2,173]

@Edel it's been over a year since you posted this.  You talk about "shrinkage" and "warpage" but people have different definitions.  In your case:

shrinkage=parts smaller near heated bed

warpage=parts lift off the bed on corners

 

Solve "warpage" by watching my video again.  Clean the bed at least once per month (see the cleaners I use - soap and glass cleaner), use liquid pva (I show 3 methods to do this), use brim for large parts, use curved corners if possible, squish the bottom layer extra.

 

Solve shrinkage - well you already solved it above if you read your posts.  Shrinkage is caused because the pla is like a liquid rubber band and pulls inward.  It's worse near the heated bed and then recovers moving upwards.  You can switch from a heated bed to blue tape.  That will help a lot (you must clean the tape with alcohol - watch the video above).  You can lower the bed temp to 50C (but now you have to pay a lot of attention to keep the part sticking on the bed - watch my video above).

 

Also printing the inner walls first can help with what you call shrinkage. I think this is on by default: "outer before inner walls" unchecked.

 

Also turning the fan on sooner might help.  But may hurt the bottom layer.  Also if you are printing small parts it may help to print a few of them. 

 

I notice you said that some parts were worse.  Maybe those are the parts where it switched layers.  If you look at the layer view in cura you can see which part or parts have the layer change - those parts don't have as much time to cool down before it starts another layer.  This only matters for small parts.

[Edel 5]

@gr5 as you know i m not english, so i m looked up that time the word in dic for that problem!

 

so

shrinkage?

 

is the problem?!? or which word? i never used warping...

 

sure i solved it last year and the year before........and i think i solved it this year also....

but i dont understand it..... in 2017 it was the bedtemp, go von 60 to 58 ,,,in 2018 vom 58 to 55 and now i m low as  52!!!

 

and the new problem came with the cura 4......so i think thats in allllllllll the many settings, one, which is for my problem.......but i dont know that factor