Small bits sticking up on faces

Sometimes when I print out a part, with a flat top, on the end of a infill line there will be a little blob near the outer wall lines. I think it is from the printer having to change direction and pauses for a moment and the extruder puts a blob down, kind off like a seam on a vertical face. Is there a setting in Cura that will eliminate this.

if you are using cura you might inspect the spots where this is happening in preview. if there is a retraction there it might be a retraction setting. if it’s just happening where it changes direction there is a setting to stop it from extruding into that corner a tiny amount of time beforehand so you don’t get a mount of goo. I forget what that setting is called exactly but I’ll look for ti and report back

Linear Advance, or Overlap settings might help.

yes, that’s it. linear advance!

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As mentioned, linear advance is likely what you need. The YouTube channel Teaching Tech does a good video on it and it’s part of his calibration guide.

My understand is it doesn’t work on all printers though because of what stepper drivers and in what mode they are running. For example it apparently doesn’t work on ender 3 v2 because it uses TMC 2208 in whatever legacy mode is. It also needs a firmware changes to enable I believe but can be tuned in the printer once enabled.

I set it up on my printer and it does work pretty well.

Is there a resaon it only happens some of the time.

Your printer has become mildly sentient and it is having good and bad days? 🤷

Does it only happen at the end of a line before a travel move or is it happening on all corners and direction chances?

If it’s only before travel it might be needing more retraction to avoid it leaving a blob.
If it’s on most corners then linear advance chances the rate of extrusion to be more even with the acceleration in XY moves.

Pictures might help
As Glenn mentioned you may be able to glean a bit of insight by looking at the movement preview in Cura and seeing what it is doing at the points that blobs are being left.

I always suspected the devil was into 3d printing. Explains a lot.

Actually there always seems to be some sized bit but sometimes it is so small as to be almost unnoticeable. I doubt it is retraction, I leave that set where Cura wants it at 6.5 MM and it seem to works well there. I haven’t looked up Linear Advance yet so that might be something. Seems to be more noticeable when a top layer is printing and the printer changes direction at the edge of a line.