Prints warping halfway through - settings or printer?

[thathollywood 0]

Hoping someone can help.

We're seeing a lot of prints that almost fail.

Funny thing is, is that they normally start out okay and then start to warp, miss lines, or extrude too much.

 

We've tried adjusting settings but it doesn't seem to clear it up.

Any advice?

 

Layer Height: 01.

Shell Thick: 0.8

Enable Retraction: tick

 

Bottom/Top: 0.5

Fill density: 0

 

Print Speed 100%

Temp: 210

 

 

[gr5 2,172]

>start to warp, miss lines, or extrude too much.

 

Sounds like 3 different problems. Maybe 3 different posts?

 

Well I'll address just one issue - around the area of the angel's wings there is some underextrusion (holes). This is caused by changes in extruder speed. Easiest way to fix this is to slow things down and also make sure your fill speed is the same as your normal print speed (movement speed should stay fast!). If you want it to be really beautiful print really slow - like 20mm/sec.

 

Alright two issues - if you want to reduce strings, lower speed *and* temperature. Try 190C or even 180C. These are dangerously cold (you can get underextrusion easily if you don't print slow enough) but temps below 200C can usually eliminate stringing. I usually go for 195C as a compromise but the best temperature depends on the color and brand of PLA:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

 

[thathollywood 0]

Many thanks.

Will give it a whirl.

Any idea why the print would start to under extrude half way through?

 

[gr5 2,172]

Because of the flexibility of the clear bowden tube there is a springiness to the pressure on the filament in the nozzle. So when you speed up you are getting higher pressures getting that PLA through that tiny nozzle, and when you slow down it reduces pressure. But there is a delay to the pressure.

So when you have a path that is a long rectangle, on the long edge you are extruding faster at higher speeds. When you get to the corner it slows down and over extrudes a bit as it approaches the corner, it then goes around two tight corners slowly and then as it accelerates out of the second corner for the long edge you get underextrusion because of this delay. That's why the angel wings have that underextrusion just on the corners. You can even tell that it was a counter clockwise movement on the right wing in the photograph at head height (underextrusion). The upper portion of that wing is probably showing a z-scar.

All of this is fixed with a slower speed as you don't have such extreme pressure changes in the nozzle because you don't have as extreme speed changes (the short distance is at the same speed but the long distance is slower than before).

This "half way through" has nothing to do with the height of the part that is being printed and has everything to do with the geometry or path that the print head goes in.