Smooth path for a bearing ball
I've created a very well working ball bearing. Eight 10 mm steel balls roll in their grooves. The 3D printed grooves turned out very nice, although Tinkercad couldn't provide very smooth torus shapes. The grooves were printed horizontally, which worked very well in the end.
But now I need to make something similar. Grooves, where steel balls roll. Now the grooves need to have a slight circular shape in the vertical plane, to create a gravitational pull to the centre of a 30 mm path.
The image shows 10 mm balls in 30 mm grooves. The 30 mm path should have a slight curvature, the middle point should be the lowest. I know how I create this in Tinkercad, but I need the print to be as smooth as possible. The balls should roll along a smooth surface. How do I avoid the visible layer edges? Or minimize them? Some special settings?
RE: Smooth path for a bearing ball
Unfortunately this forum isn’t great for design or engineering advice. Look up CAD constraints and choose your adventure.
Tilt your part at, say 30° or 45° to the print sheet; it will require a lot of support but you should be able to reduce the effect of the layer lines.
Cheerio,
RE: Smooth path for a bearing ball
It's been a long time since I used TinkerCad but I assume you have used the maximum number of "steps" for the round objects you used to create the grooves. Tinkered is great to get started but maybe it's time to move on to Fusion or FreeCad to get the tools that allow you more control over your model and its resolution.
On the slicer side, make sure you use higher resolution, such as 0.1mm layer height. You can also try to use the Variable Layer Height option to get better resolution. A final thought: Print it in ASA, and you can use acetone smoothing to get a perfectly flat surface. In this case, look like you need precision on the outside, so instead of vapor smoothing I would just dab a tiny bit of acetone into the grooves.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Smooth path for a bearing ball
You can turn the part 90° (print it vertically), such that the layer lines run in parallel with the large-radius curve of the grooves. You may need to print the upper part (which seems to have grooves that are orthogonal to each other) as two parts, upper and lower slice, to keep the groove curves aligned with the layers.
By the way, your current design is not properly constrained. Balls running in grooves with a circular cross-section do not have a well-defined lateral position; it's better to use V grooves. And I would use three balls per plane instead of four to avoid over-constraining the planes and getting a "wobbly table" effect.