Small Part Z-height Dragging

I’m testing the limitations of small part printing and have a weird issue. My extruder begins to drag through layers. It seems like the outside perimeter is extruding too much, building up, and causing the drag. I can print larger parts with no issue - so I don’t think it’s hardware… I’m using a 0.5mm and have tried 0.18 and 0.25 layer heights (both with 0.6mm width) - no difference. I’m using S3D for slicing and have tried 0% infill (just perimeter) and 100% infill, but S3D doesn’t perform the infill lines - it skips them.

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It might be due to heat in your part, you nozzle is dragging above not fully cooled lines. On big parts, there is no isue because during travel moves your old lines are coold down and the hot nozzle is toughing them only a short time. Maybe also in combination with shrinking, the lines become “smaller” if they are cooled down, so they have a little bit more space to the nozzle than the fresh laid hot ones.

So, try to increase your fan speed or print 2 or more parts at once. As for the infill, I have no idea. Maybe a bug…

Looking at the gcode viewer picture there is no place to have infill. It just shows internal and external layers with no room to have a infill layer.

As for the dragging issue you will need to allow lots of cooling time for small parts. AKA - print multiple so each has time to cool, the smaller the part the more you would need to print. You also do not say if you are using any Z lift or much of anything software wise.

If you want S3D to do infill on a part that small, you will need to reduce the width of the infill to 100% and probably only use one perimeter.

You might also need to increase your outline overlap to 50%. S3D has some issues with thin walls. They have made improvements but some issues remain. Generally, you can get the infill you want by reducing the number of perimeters, if your design will tolerate it.

I noticed that drag on small parts is more of a problem with HIPS than ABS. But this was with Cura and slic3r with the Lulzbot profiles. I don’t know whether the difference was due to the profile or a property of the material.

I’ve ran a series of tests and confirmed that it was heat-related. I printed two identical parts 10cm away from each other and the problem went away. Then, I printed a single part with 100% fan. I increased the print speed up to 200% (120mm/s) and the part came out perfect. Thanks!

Also, I upgraded the bearings to JSB linear bearings and hardened rods. I’m not sure if this has made a print difference but the toolhead x-axis and build platform y-axis move much easier when the machine is powered off.