Alternatively invert clockwise direction of perimeters #1073

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rohieb opened this Issue Mar 29, 2013 · 8 comments

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rohieb commented Mar 29, 2013

Like mentioned in #328, printing overhangs with edges tends to cause upward curling. In my case, this even happens with a print speed of 20mm/s and full ventilation when printing the small extruder gear (which basically only consists of edges) for the @reprappro Mendel. I observed this issue a while when printing things, and I think the core problem here is that the extruder pulls the still hot filament with it in its travelling direction, causing edges to be "shortened out". But since the filament is still attached the the lower layer, this causes tension inside the print, which in turn causes the edge to curl upwards.

So, as a possible solution to this problem, I propose to print the perimeters in clockwise and anti-clockwise direction alternatively, in order to eliminate this effect. Since I haven't tested this in practice (no favor for crafting my own GCode ;-)), I currently cannot say anything about the effectiveness of my solution.

nophead commented Mar 29, 2013

I do that in my own software but I don't think it helps with curling. It
does improve the symmetry of gear teeth though and generally makes corners
a bit sharper. The downside is any backlash shows up as ridginess.

On 29 March 2013 20:55, Roland Hieber notifications@github.com wrote:

Like mentioned in #328 #328,
printing overhangs with edges tends to cause upward curling. In my case,
this even happens with a print speed of 20mm/s and full ventilation when
printing the small extruder gearhttps://github.com/reprappro/Extruder-drive/blob/master/Print-mendel-mult-material/Individual-STLs/small-gear-1off.stl(which basically only consists of edges) for the
@reprappro https://github.com/reprappro Mendel. I observed this issue a
while when printing things, and I think the core problem here is that the
extruder pulls the still hot filament with it in its travelling direction,
causing edges to be "shortened out". But since the filament is still
attached the the lower layer, this causes tension inside the print, which
in turn causes the edge to curl upwards.

So, as a possible solution to this problem, I propose to print the
perimeters in clockwise and anti-clockwise direction alternatively, in
order to eliminate this effect. Since I haven't tested this in practice (no
favor for crafting my own GCode ;-)), I currently cannot say anything about
the effectiveness of my solution.


Reply to this email directly or view it on GitHubhttps://github.com/alexrj/Slic3r/issues/1073
.

Owner
alexrj commented May 10, 2013

As in, printing one layer's perimeters in one direction, and then using the other direction in the upper layer?

rohieb commented May 10, 2013

@alexrj exactly.

Owner
alexrj commented May 10, 2013

@nophead, do you think it would be a good idea to make this the default behavior, without any option to disable it? It would force people to eliminate backlash from their printers.

nophead commented May 10, 2013

It does show up any backlash, so prints do generally look prettier without
it. I expect you will get complaints from the people that print vases, owls
and yodas if you don't make it optional.

On 10 May 2013 18:08, Alessandro Ranellucci notifications@github.comwrote:

@nophead https://github.com/nophead, do you think it would be a good
idea to make this the default behavior, without any option to disable it?
It would force people to eliminate backlash from their printers.


Reply to this email directly or view it on GitHubhttps://github.com/alexrj/Slic3r/issues/1073#issuecomment-17732336
.

Contributor
harriv commented Mar 2, 2014

@alexrj I think this should be default behavior when not using spiral vase mode. I noticed same problem with my print and "invented" same solution as @rohieb.

mrbi11 commented Mar 2, 2014

This would have the effect of immediately going back over or by fills
that were just laid down, and so are not yet solidified, and not yet
cooled, which also means they are larger than they will be when they are
cooled.

What benefit do you think this will have?

*peace,
Bill Kelley

  • 512 266 1896

On 3/2/2014 1:07 PM, harriv wrote:

@alexrj https://github.com/alexrj I think this should be default
behavior when not using spiral vase mode. I noticed same problem with
my print and "invented" same solution as @rohieb
https://github.com/rohieb.


Reply to this email directly or view it on GitHub
#1073 (comment).

Contributor
harriv commented Mar 2, 2014

@mrbi11 There's usually also the infill to print which gives some time to cool down. The benefit would be reduced curling in overhangs, especially when doing sharp corner over half-empty space. When doing perimeter always same direction, sharp corner slowly "travels" (and curls) to the direction of nozzle movement if it hasn't completely solidified yet. More cooling, yes, but at least in my test piece it would require stopping printing for a while between layers to allow even more cooling what my fan can achieve..

@alexrj alexrj removed the Needs more info label Mar 12, 2015
@lordofhyphens lordofhyphens added this to the Pull Request or Bust milestone Mar 19, 2017
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