Cylindrical part issue, wall thickness, and gap

[tyler_farrell29 0]

ive been trying to print a cylindrical spacer type part. i have designed it with wall thicknesses between 0.01-0.10mm thickness to try "trick" cura and repetier host into creating the gcode so it only forms one loop (the width of the nozzle wall thickenss) yet regardless it makes two loops doubling the wall thickness (0.08mm). which would be acceptable however, it forms a gap in the front by doubling back when it makes these circular loops/laps. please help

 

[illuminarti 18]

This is a tricky thing to print the way that you want it - because you're modeling the upper circular part as a hollow STL, the slicer is printing two walls - and outer one, and an inner one, each one loop thick, for two loops over all.

Best option would probably to model it with the upper cylinder solid, and then slice it twice - one normally, and one with zero infill, and wall thickness = nozzle width. Then manually merge the gcode files together at the transition point.

(Or slice it once, and edit out the solid-base-in-mid-air that it will try to print on the upper cylinder?)

 

[gr5 2,196]

This is a difficult print but I think you can print this gcode with no changes to cura. Instead I can see you have some "play" also known as "backlash". Try tightening all your belts a little bit (especially the short belts from motors). See these pictures and descriptions:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=14396

Zoom in on the above picture and read the text that goes with it, then zoom in completely.

Also scroll down two posts to see how backlash causes the gaps you are seeing (both on the cylinder where it does it's "doubling back" and also where the circular pad meets the cylinder.

Illuminarti's suggestion is pretty good but may be difficult. Basically there is a "mode" in cura where you can print a cup. The STL for the cup is a solid cylinder but you tell cura to leave the top unfilled. When printing a "cup" the walls are almost always .4mm. This won't work with your circular base. That's why he suggests slicing the two parts of your part with two different methods and then mixing the gcode back together. But I think just tightening your belts might be good enough if you are okay with a .8mm thick wall.

 

[gr5 2,196]

Oh - as a final hack you could make your cad drawing wall .6mm thick and tell cura your nozzle is .3mm (even though it's actually .4mm). This will put the two passes of the cylinder walls closer together.