Effects of temperature on PLA, how should the finish on parts look?

[xenogea...@gmail.com]

Last weekend I was trying some different settings in an attempt to figure out why my extruder was locking up on 100u prints.  I printed out some 20mm test cubes at different temperatures.  I did a couple at 225C and 230C and they came out as I expected and had seen in the past.  They have this shiny, glossy finish to them with a sheen that sort of reminds me of oil on water.  But then I decided to print some out at 200C and 205C.  Surprisingly (at least to me), they came out with matte finish that was even and consistent, not shiny, and it was harder to see the layers, they weren't as distinguished.

What is the finish supposed to look like?  Is it just a matter of preference?  It appears to me that the higher temperatures are changing the plastic somehow but could that change be a contributing factor to failed prints?

[Eighty]

MBI insists that 230C is appropriate for PLA, which is contrary to most (if not all) manufacturer literature. I find that lower temps work better for reliable printing, but YMMV.
But to answer your question, yes, I've found that there's a big difference in shininess. Even between 220 and 230.

[abellasr]

On Monday, April 1, 2013 4:05:18 PM UTC-4, xenogea...@gmail.com wrote:

Last weekend I was trying some different settings in an attempt to figure out why my extruder was locking up on 100u prints.  I printed out some 20mm test cubes at different temperatures.  I did a couple at 225C and 230C and they came out as I expected and had seen in the past.  They have this shiny, glossy finish to them with a sheen that sort of reminds me of oil on water.  But then I decided to print some out at 200C and 205C.  Surprisingly (at least to me), they came out with matte finish that was even and consistent, not shiny, and it was harder to see the layers, they weren't as distinguished.

What is the finish supposed to look like?  Is it just a matter of preference?  It appears to me that the higher temperatures are changing the plastic somehow but could that change be a contributing factor to failed prints?

We just started to print with ABS last week so I am certainly no expert.  I would think the finish should match what the filament on the roll looks like?  If it is shiny, it should be shiny after extruding.  If it starts out matte, it should come out matte?

[Jwo Fox-Lee]

I believe it's about how PLA crystalizes when it cools.

I've printed at as low as 185 and as high as 130 on the same filament, and get very different looks.

- Jwo Fox-Lee

On Mon, Apr 1, 2013 at 1:05 PM, <xenogea...@gmail.com> wrote:

Last weekend I was trying some different settings in an attempt to figure out why my extruder was locking up on 100u prints.  I printed out some 20mm test cubes at different temperatures.  I did a couple at 225C and 230C and they came out as I expected and had seen in the past.  They have this shiny, glossy finish to them with a sheen that sort of reminds me of oil on water.  But then I decided to print some out at 200C and 205C.  Surprisingly (at least to me), they came out with matte finish that was even and consistent, not shiny, and it was harder to see the layers, they weren't as distinguished.

What is the finish supposed to look like?  Is it just a matter of preference?  It appears to me that the higher temperatures are changing the plastic somehow but could that change be a contributing factor to failed prints?

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[delsydsoftware]

Layer height really makes a difference in the shininess of ABS. For example, here is a squirrel printed at 0.27 layer height versus one at 0.08 layer height. The 0.08 squirrel has a matte finish, while the 0.27 squirrel is much shinier: