How would you slice this stl?

Hi all,

I'm posting this picture of a design I need to print. As I'm very new to 3d printing I would greatly appreciate it if you have any tips for slicing this object. For instance on the orientation of the object. Is it best to print it upright like in the picture, with support material underneath the wide overhangs and the tubular sections? (I will try with both skeinforge and slic3r)

Thanks very much in advance,

Niels

BTW Right now I'm trying skeinforge with the raft setting (set base layer and interface layers set to 0 to ingnore the raft) turned on so I'm able to use the support function. It seems it's doing a good job so far but unfortunately the support structure lifted off the bed and warped the print

Edited 2 time(s). Last edit at 11/11/2013 06:31PM by Nilez.

The support structure came out too dense (lines very close to eachother) and bonded too strong to the object with Skeinforge. Guess I have to lower the support flow rate ratio

Edited 1 time(s). Last edit at 11/11/2013 08:10PM by Nilez.

Is the object flat on the rear? If it is, I would turn it 90 degrees backwards so the hole collars point upwards.

I find that holes print better in the X-Y plane than in Z and if the piece has no protrusions on the rear it will provide a good surface for adhesion without the need for support.

A link to the STL or all-round views would help a little more.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Hi Neil

Thanks. I should have mentioned that the rear surface is slightly curved. The curve has a radius of 6.5". I've sliced it upright in Skeinforge and although the print failed due to a lift from the bed, it managed to complete the holes which came out nice. Slicing it with the back surface flat should result in less support material though since the curve is pretty shallow, so I'll give that a try

Edited 1 time(s). Last edit at 11/12/2013 06:19AM by Nilez.

If it is PLA and you have a suitable former it might be better to make it flat and then heat it and bend it around the radius. Cheating with respect to 3D printing but that is not an easy shape to make.

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[www.hydraraptor.blogspot.com]

Hi Chris,

Yes it's PLA. That trick you mentioned might work because the object sits on the inside of a shell with the same inner radius so I could use that as a former. But I think I like the way it came out. As you can see in the picture mendel90 can handle the job with the upright slice I had to bump the brightness of the picture to show some more details of the object since it's printed in black PLA.

Still wonder if I can do something about those bumps on the surface which I experience in all of my prints. Is this something I just have to accept? I believe Jitter function spreads these out because otherwise you would get a seam?

Edited 1 time(s). Last edit at 11/12/2013 03:14PM by Nilez.

What speed are you printing at? The position of those bumps makes me wonder if it could be 'ringing' - a kind of oscillation of the print head after turning a sharp corner. If so, printing slower or decreasing your acceleration settings should reduce it.

Hi Richard,

It was printed with a feedrate setting of 60 mm/s (flowrate the same) and the travel feedrate is set to 200 mm/s (standard setting in nopheads' PLA 0.2 profile). I believe that Chris has set the accelleration to 2000 in the firmware (instead of the former 4000).

Now that you speak of ringing, I have attached a picture which maybe shows a further indication of this?

Edited 1 time(s). Last edit at 11/13/2013 06:11AM by Nilez.

Hmm.. I was just thinking about curved surfaces in Sketchup not being being true curves but more a connection of linear segments which are displayed like a smooth surface. Maybe the segments show up in the print again. The pattern in the picture is more pronounced at the far ends of the object though...

Edited 1 time(s). Last edit at 11/13/2013 07:47AM by Nilez.

Hi Nilez,
That looks more like vibrational ripples than Sketchup stepped curves. I use Sketchup all the time for drawing objects I print and when I haven't put enough steps in a radius/circle it will show as straight facets in the print. You know you can smooth a Sketchup Arc/Circle by typing xxxs just after drawing it, where xxx is the number of steps in the curve. The greater the number the smoother the curve, e.g. 96s gives a reasonably smooth curve.
If you want to mail me the .stl I can print off your part so you can compare. Up to you.
NumberSix

Hi numbersix,

I totally forgot to reply to your above message. Meanwhile I figured it is indeed due to vibrational ripples. I'm printing with feed and flowrate at 60. The arcs used in Sketchup were divided into 96 segments. I also changed the design a bit but I would love to see how the part turns out on your printer so I'll mail you the stl. That is of course if you're still interested in doing that. I'll pm when I have the new part done.

Nilez

Hi Nilez,
Send me on the file and any other variables you'd like me to consider in test printing, fill density, layer height, etc. I'll run a few tests and return some picts to you.
Not a problem. "All in the aid of science", or 3d printing, as the case may be! :-)
NumberSix

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[numbersixreprap.blogspot.com]