Lines on surface

[oliver-fueckert 0]

Hi Guys,

Now that I have my Ultimaker for a week, I have tried a selection of slicers, like Slic3r, Netfabb and Cura. I got to say, even after playing with the parameters quite a bit I still get the best results in Cura. Thanks for a great piece of software!

One small thing I noticed are lines which are especially pronounced on the surface of objects. They are related to the blue line seen here on the model:

It seems like the slicer moves across the whole surface to start the layer fill on the opposite side ((starting front left in this pic to back right) and then the layer is printed perpendicular to the blue line which leaves a nasty line across the surface.

I was wondering why it does that ? It could just start the layer from the front left instead of moving over to the other side first to avoid this line across?

Here the printed result for reference:

best regards,

Ollie.

 

 

[gr5 2,069]

The picture is too blurry. Is it extruding during the move? If so you can enable retraction and also uncheck "retract on jumps only". This will slow down the print and maybe make things worse but if it is extruding during that blue line it *will* help that one thing.

Hopefully Daid's new slicer (coming out soon!) will infill in a smarter order.

 

[oliver-fueckert 0]

Yes, it is extruding all the way across. I'll give retract on jumps a shot to see if that will make it better.

Thank you for the tips !

Ollie.

 

[baasb 6]

Yes, that definitely makes it better! But unfortunately Cura makes a lot of 'unnecessary' movements which causes imperfections... Hope that the new slices makes a big difference regarding these movements :smile:

 

[gr5 2,069]

If you only care about one of the spots on your print - I assume the bottom or top layer. Then you can edit the gcode yourself and put in a retraction move. Slice it both ways, look at the difference between the 2 files on the layer(s) you care about and just add retraction on those 2 layers only.

The gcode files are easy to read and edit. Each layer has a comment along with where perimeter starts, infill starts, loops start and so on.

Well not as easy as looking at a picture of the moves but just try it!

 

[illuminarti 18]

Even with retraction enabled you're going to get this kind of problem because the head does travel moves across the surface, damaging it. What you might want to try is enabling the 'hop on move' capability, so that it lifts off the surface during moves. But Cura's not very smart about that - you might get better results with the equivalent setting in Kisslicer. You should also take a look at my blog post about z move speeds, and consider tweaking things to get slightly faster z-moves...

http://www.extrudable.me/2013/04/02/the-myth-of-z-speed/

 

[oliver-fueckert 0]

Thanks for all the replies. Things look much better now. And nice writeup Illuminarti!

 

[Daid 304]

Note, it's not extruding during the blue moves. Those blue lines are just moves without extrusion. But, yes, they do scar the surface.

The new engine does a bit better, but there will always be moves on the top surface, no way to prevent it without teleportation.

 

[edis 0]

That would be a nice feature in cura, teleportation :mrgreen:

 

[illuminarti 18]

But isn't raising the z height for moves (especially on exposed horizontal surfaces) almost as good as teleportation, and quite a bit easier with current technology?

 

[Daid 304]

In my experience, z-hop makes everything worse as it leave nasty blobs unless you print slow and at a low temperature.

 

[illuminarti 18]

Yes... which is why I'd be interested to only turn it on for finished flat surfaces and/or have aesthetically aware path ordering for finished surfaces. :-)

1 small blob is easier to clean up than a stripe all the way across the surface of a print.

 

[makingzone 2]

This Z move option could be activate or not n'y the user with a checkbox...