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Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 10:28 am
by frijoli
horst.w wrote:
I guess you have a direct-extruder (not bowden ???) , because your retract was only 0.8 mm. If NOT, then 4 - 5 mm is right.
It needs to bring out by pulling back all pressure out of the melting chamber.

Your unusual high temperature of 215 / 200 -depending to a slow speed - (PLA 190 - 210, optimum you must find out!) cause a escape of molten filament after the pressure is zero. Therefore you must give a negative (!!!) value to Retract-Extra-Restart, you must lift the nozzle to have a proper new beginning of print on the next tower. No wipe and No Coast at end!

I think your adjustment of printing speed down to 5 % (Cooling) is very contraproductive, but you must find it out.

H.
Yes direct extruder
I will try no coast-no wipe.
What change did you make to the FFF? It looks exactly like the file I started with.
I don't understand your comment 5% cooling.

Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 3:27 pm
by dkightley
I don't understand your comment 5% cooling
This refers to your cooling Speed Override - adjust speed for layer below 15 seconds...allowing speed reduction down to 5%

Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 5:35 pm
by frijoli
dkightley wrote:
I don't understand your comment 5% cooling
This refers to your cooling Speed Override - adjust speed for layer below 15 seconds...allowing speed reduction down to 5%
Do you think is is too slow? I didn't set this, but I assumed lower was better.

Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 5:40 pm
by frijoli
Thank you everyone for your help. I am very close now.
Wipe and coast were causing the issues for the most part. I have them turned almost all the way off.

Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 6:03 pm
by horst.w
... the factory-file I have attached is a copy of yours, but very different to your settings
Import it to your S3D (<File> <Open factory> .... and use it as a base.
If it needs to vary, do that everytime with only one step.
The most importend thing is the accurate setting of the extrusion and when you are able to print such a lot of towers without any blobs your settings of extrusion, temperatures, speed, cooling, retracts, restarts, lifts a.s.o. are ok.

At last, all proving of settings needs to do, when changing a roll of filament. They are never identical.

H.

The last print of this day: (12 small towers to test glueing of the material -ASA-)
20170702_201138[1].jpg

Re: Blobs on top ONLY

Posted: Sun Jul 02, 2017 6:39 pm
by horst.w
frijoli wrote:
...
This refers to your cooling Speed Override - adjust speed for layer below 15 seconds...allowing speed reduction down to 5%
...
Do you think is is too slow? I didn't set this, but I assumed lower was better.

That is a typical "One-side" - "Other-side"-problem.

First it needs to print as slow as possible and do cooling (PLA) as fast as the fan can blow.
But the other side is that the nozzel is going around over a very, very small area and the print of the 2 needles is so quick one after the other, that the extruded material has no chance to cool down and becoming hard. That happens also with only 5% speed of your 40 mm/s. The next layer to print brings new, very hot, melted material to a warm and soft underground and the nozzle will press down the top . Thats the begining of your "onion" on the top of the needle (+ extremely over-extrusion). PLA has a soft-point-temperature of 60 - 70 °C. To become it hard, you must cool down more than 100 °.

The best way to solve this problem is a second print of anything far away on the print bed to win time.

H.