cylinder has corrugated look

[Deereengineer]

Any time i print a perfectly cylindrical part i get this corrugated look. Its a little hard to tell from the picture but it looks like every few z up movements it has is a different height. any ideas?

[insta]

Is that on an M2? What layer height are you using?

[ednisley]

any ideas?

In no particular order:

• Extrusion Multiplier calibrated -- thread width matches what the slicer expects
• Extrusion temperature set correctly -- too high can produce slumping
• Extruder motor tight in X motor mount -- check for cracks
• Hot end (particularly V3) tight in mount -- check for wear / melting
• Infill pattern dense enough to not affect perimeter -- no periodic voids
• Too few perimeter threads for infill pattern -- collapses in sparse sections
• Too many perimeter threads for infill pattern -- bulges in dense sections

It's always a good idea to check the thread paths produced by the G-Code (using the slicer preview or http://gcode.ws/) to see if the patterns match up with what you're seeing in the object: sometimes an obvious gotcha pops out at you.

After checking all that, take another picture with crisp focus...

[Deereengineer]

yes its an m2. layer height is .2 mm

[jimc]

do you see these ripples in any other parts or just round ones?

[Deereengineer]

Only the round ones. No problem anywhere else

[ednisley]

Only the round ones. No problem anywhere else

A modeling gotcha may also be in play...

STL files represent cylindrical surfaces with triangles, so a perfect cylinder model becomes a gazillion triangle slivers. The slicer turns those slivers into ten gazillion G-Code commands that can choke the poor Arduino driving the printer; an interaction with the infill pattern may produce periodic imperfections.

Converting the cylinder into a polygon with faces about 0.5 mm wide at the perimeter may improve the results by reducing the number of pauses / slowdowns due to Too Much Data.

[Deereengineer]

Ed, could you explain your last 3 suggestions a little more in detail.?

[willnewton]

I think he means that you have so many polygons the Arduino is choking on them and that you might possibly reduce the polygon count and see improvement.

Questions to rule stuff out.

1. Is the layer speed changing in a noticeable fashion as it prints?
2. Or is the hot end temp fluctuating?
3. Are you using S3D for slicing? If so have you checked the G-code preview to see if the defect shows up there? Does the defect show up if you change the layer height?
4. Is it the round object in your original post or every round object you print that you are having trouble with?
5. You printing via SD or USB?

[Pekish79]

don't draw a circle draw a polygon with as many faces as needed to look curve

autocad does it automatically when exporting (and per default has a really lame number of faces that u usually need to manually improve to have half decent results on big circles)

so what he is saying is draw yourself a polygon with as many faces as it's needed to look curve so you will have better control on the generated G-code

usually small circle up to 1" or 2" diameter are okey as 30-60 faces on a small circle will look almost perfectly curve the bigger the circle the more faces you will need to make it look curve and if the program generate too many it will be get really have as a G-code