Sphere / Problem with last layers

[closedcircuit 0]

I'm trying to print a fairly small model (about 4cm) on a UM2. The last layers represent the top of a sphere but end up being completely messed up (see pictures).

What it should be:

 

How it comes out:

 

I have tried varying nozzle temp. from 190, 200, 210, 220 and 230 and speed from 50mm/s X 50%, 50mm/s X 75% and 50mm/s X 100% but always end up with the same issue.

 

Otherwise:

 

Bed temp: 60

Layer height: 0,06

Shell: 0,08

Bottom/top thickness 0,6

Brim enabled

Filament: PLA Orange from UM

 

Model (.obj): https://dl.dropboxusercontent.com/u/109695611/2014-05-04%20---%20Cours%20de%20Cuisine%20v0-9.obj

 

Could anyone point me in the right direction? I've had some really great results recently, but I just don't seem to get this specific model to print properly...

 

Thanks!

 

Phil

 

[Dim3nsioneer 356]

First, set the minimum layer time to 5-7s in order to give the deposited material enough time to cool.

The minimum speed should not be below 10mm/s.

Furthermore you can try the cool head lift feature.

Personally, I use either the Flowthermostat plugin or the TweakAtZ on the layer where the print speed drops below 25-30mm/s.

 

[closedcircuit 0]

@dimensioneer: Thanks for your help. Mininum layer time was 5s. I've pushed it to 7s. I have also installed Flowthermostat which looks great - good tip, thanks.

Could you please clarify what is the cool head lift feature and where I can find it?

Thanks a lot!!!

 

[gothampixel 10]

Try printing two or more at the same time. This gives the layers more time to cool without having to slow down the head. I believe increasing the layer time on small objects can make things worse by keeping the hot end over the layer for too long.

 

[closedcircuit 0]

@Gothampixel: Thanks - it's a very good idea. I'll wait for the current trial to finish and then I'll do two at once.

Cheers!

Phil

 

[Dim3nsioneer 356]

@dimensioneer: Thanks for your help. Mininum layer time was 5s. I've pushed it to 7s. I have also installed Flowthermostat which looks great - good tip, thanks.

Could you please clarify what is the cool head lift feature and where I can find it?

Thanks a lot!!!

 

Instead of slowing down the print speed due to the minimum layer time, the layer is printed with normal speed. For the remaining time of the layer, the head is lifted.

You find the feature in the expert settings of Cura.

 

[restinpieces 3]

I find the result pretty good! It's a very nice clown face... Oh wait that should not be a clown face u say? :mrgreen:

 

[closedcircuit 0]

Thanks for your explanations, Dim3nsioneer.

The first couple of tries with Flowthermostat were a bit of a disaster, but I've no doubt that it's because of me rather than the extension. I keep on googling...

Cheers

 

[closedcircuit 0]

@restinpieces: Looks like someone ate a clown before posting...

 

[Dim3nsioneer 356]

Thanks for your explanations, Dim3nsioneer.

The first couple of tries with Flowthermostat were a bit of a disaster, but I've no doubt that it's because of me rather than the extension. I keep on googling...

Cheers

 

You most probably have to increase the coefficient. The plugin requires some time until it works as it should. Could be I even found a bug and eliminated it; but can't remember right now. I'll have to check.

 

[closedcircuit 0]

Thanks. Gothampixel's solution worked quite well (although I've had to increase the number of pieces to four). I'll play some more with Flowthermostat tomorrow to better understand coefficients, etc.

 

[gr5 897]

If you print 4 pieces the 2 in the middle will come out better so instead you could print towers on the ends (just cylinders) that are at least .2mm taller than your part.

Cool head lift works somewhat - it's not as good as printing multiple parts but sometimes you don't want to print multiple parts. For example printing large things with a tiny top. Cool head lift is under expert/cool section I believe.

 

[gr5 897]

Oh - and it helps quite a bit to have the fan running at 100% but the default is to not have the fan at 100% until 5mm up the part so I usually have the fan at 100% by 1mm or 2mm height.

 

[closedcircuit 0]

Thank you all. The print was completed just in time and looks good. I've really appreciated all the help!