Printing ugly corners

Hi.. just upgraded to Marlin firmware and using SFACT with a heated bed.. Im getting some poor results and kinda stuck on how to get it to work..

Before I was using Sprinter and Skeinforge with the transparency film bed, I managed to get some decent quality print, but now even printing the 0.5mm wall or the 20mm box, I'm getting poor results.

Please have a look at the pic.

i am printing PLA and set the perimeter speed to 25mm/sec at 175C, the box on the left was printed at 0.4mm thickness and the one on the right was at 0.25mm. as you can see the corners started very square at the bottom and as it went up the corners started to become rounded and were sticking up for about 1mm!

I wondered if the PLA was too hot, and now i got it to 175C but still getting the same result.. Also I tried changing the feed and flow rate but couldnt see much improvement..

Can somebody tell me where I should be looking at to solve this problem?

Many thanks.
Adrian

You should start using Slic3r

www.slic3r.org

i know.. it's so much easier.. but does slic3r has support material functions? coz thats what I really like from skeinforge.. otherwise its too much setting

also i think there are many situations especially with architectural buildings that slic3r doesnt slice properly...

in sfact setting select tab for speed settings reduce your perimeter flow rate by 10% this will reduce the goo of the lines.

finish adjusting flow rate until it looks better.

sfact has a skin feature that is scripted in to its skein, even when disabled in skienforge. your flow rate needs to basically be perfect, or a little lower to work properly with half height skin feature . at normal height close does ok, but at half height of skin feature on perimeter it gets too wide. this is probably why your settings seemed to work before.

to clean up of the perimeter layer, have it so z moves only happen inside of part.
Go into fill section of skienforge and try perimeter settings in the middle such as infill-.perimeter-loops. you cant get rid of all the defects but you can make them not appear on the outside of part. if enabling this does not work for you then change settings back.

the skin script also does not have speed limitations on z axis, or if it does it does not always work properly, so the max speed in firmware should be set to your homing speed. this is also why some people have issues with irregular height.

Edited 1 time(s). Last edit at 01/10/2012 03:52AM by jamesdanielv.

thanks very much, I'll give that a try.

i managed to get the 0.5mm wall print to fairly good quality with only just 4mm/sec perimeter speed.. is this normal or too slow??

I print at 32mm/s, perimeters at 16mm/s.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

rob,

and you still good corners and layers at that speed printing the 0.5mm wall??

Will that be anything to do with the heated bed making the PLA too soft?

No, as long as you don't have the temperature set too high.
For PLA 60°C is about perfect.

Edited 1 time(s). Last edit at 01/10/2012 05:02PM by rhmorrison.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

You need to recalibrate the e-steps in your firmware. Look up Prusa Jr's Calculator. Sorry I don;t recall where it is.

i thought I've already set the e steps accurately... maybe I'll do it again then.. but slowing down the Z and flow rate does solve most of the problem...

BTW... I'm able to find the number of LOOPS in SFACT?? All I'm getting is just the perimeter and infill.. where can I find the setting for it?

I think you are looking for this..

sfact settings->infill->what order to print.

james:

I could find the print order.. but for some reason my prints seem to have missing loops...

I'm just getting 1 layer of perimeter, then the infill.

Also, if you're not using Marlin firmware, that will make your corners look much nicer too. Sprinter has bad blobbing problems.

I thought Marlin produces much better quality prints than Sprinter?!

Also.. apart from Skeinforge has the function to produce support material, any other slicer can do that?? I really need support material because I want to print architectural models and there are many overhangs...

Will there be anything to do with the acceleration in Marlin that can improve the corner quality??

ahbtsang Wrote:
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> Will there be anything to do with the acceleration
> in Marlin that can improve the corner quality??

Marlin has an extruder advance feature which helps a LOT when printing corners at high speed. There's some delay from extruder stepper motor rotating to the plastic actually coming out and the advance tries to compensate this. Here's an example of 40x40x5 block printed at 150mm/s:

[www.youtube.com]