Mad Cura result, why?

Hi,

Got my machine working, but now I have a problem that I don't get.. Probably something I overlooked..

Got my machine to print the android model that came as gcode. Installed Cura as that seemed like the easiest software for slicing and printing. Managed to print an owl using that.

Then I tried a gear set (http://www.thingiverse.com/thing:23030), and now this is what my printer does:
[www.youtube.com]

Just out of curiosity, does anybode here understand why it might do this to me? It seems like it goes crazy at the edges.

Here is [www.thingiverse.com] printing through Cura:
[www.youtube.com]
Seems to me like this too is outputting too much material at times..

Anybody got any idea as to what I'm doing wrong?

edit 1: think it might have something to do with relative vs absolute extruder values... Trying to add M82 to the start.gcode... Have to wait until tomorrow to get the results - time to sleep now...

edit 2: Yup, the problem was that Cura produced gcode with absolute extruder commands, but the nophead-Merlin firmware in my mendel90 was expecting relative commands. This made the extruder move crazy fast at times and not at all at other times.
I will now write down some search terms I used when googling for this, so other can find this solution (i.e.: put M82 in Cura start gcode or change Marlin fw to absolut extrude)
mendel90 extrusion problem intermittently too fast extrude marling Cura print goes crazy

Edited 2 time(s). Last edit at 05/31/2013 12:09PM by Torkel.

Did you mean M83?
Set E codes relative while in Absolute Coordinates (G90) mode

This is what the first 5 rows of my Slic3r generated gcode look like:

G21 ; set units to millimeters
M107
G28 ; home all axes
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion

More codes in here:
[docs.google.com]

richgain Wrote:
-------------------------------------------------------
> Did you mean M83?
> Set E codes relative while in Absolute Coordinates
> (G90) mode
>
> This is what the first 5 rows of my Slic3r
> generated gcode look like:
>
> G21 ; set units to millimeters
> M107
> G28 ; home all axes
> G90 ; use absolute coordinates
> M83 ; use relative distances for extrusion
>
>
> More codes in here:
> [docs.google.com]
> w5tnxt1jCV6Ikb9nTI2Gbo9SzCwLw/edit

Daid outright refuses to add a relative extrusion button to Cura and you must use Absolute extrusion unless you want to manually set relative in one of SF's files inside Cura.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

What is his objection to it? Absolute E is bonkers IMHO. It makes it much more difficult to change filament mid print.

---

[www.hydraraptor.blogspot.com]

As Sublime says, you need to amend one of the files in CURA.
To set CURA to produce GCode which is based on relative extruder values I navigated to a file in the CURA directory called settings.py and amended the Relative and Absolute Extrusion values to TRUE and FALSE respectively with a text editor. This followed advice obtained after I raised an 'issue' in Daid's CURA GITHUB repo (issue #385 which is now closed but carries a brief insight regarding the strengths and weaknesses of relative/absolute extruder values).

Alan

Edited 1 time(s). Last edit at 05/31/2013 02:16PM by Alzibiff.

nophead Wrote:
-------------------------------------------------------
> What is his objection to it? Absolute E is bonkers
> IMHO. It makes it much more difficult to change
> filament mid print.

I agree that relative it the only way to go for other reasons as well. Like finding errors in the gcode file and splicing multiple files together.

Here is the discussion I started about it. [github.com] Daid claims there are severe rounding errors in relative extrusion and skeinforge. I think it is an old wives tale and he can not present any proof that it effects the prints.

And here again I ask for proof of his claims of rounding errors that cause issues. [github.com]

---

FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Is it just coincidence his avatar is a cat and yours a dog?

If an error of +/- 0.5 times the last decimal place is significant then there aren't enough decimal places in the gcode.

Edited 1 time(s). Last edit at 05/31/2013 06:59PM by nophead.

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[www.hydraraptor.blogspot.com]

Hi,

i updated cura to use relative extrusion values. The file Cura\slice\cura_sf\fabmetheus_utilities\settings.py gives you access to all skeinforge settings.

Find the section named dimension and update the following lines:
'Absolute_Extrusion_Distance': "False",
'Relative_Extrusion_Distance': "True",

By using joris my Mendel90 prints nice vases

I just downloaded the latest version of Cura and there is no Cura\slice\cura_sf folder any more.
Does that mean we don't have the Relative E option any more?