What causes this

[PaulK 14]

Material is ABS. Printer is direct drive mostly home-grown. Prints well with Simplify3D, I'm trying to dial in a profile in Cura so I only use one slicer.  Retraction is enabled, 1.4mm (same as Simplify3d)

The picture is a print which has been snapped off at its weakest point. The ... weak bit we see here is the *beginning* of the perimeter, i.e. it is where Cura starts a perimeter. Now one problem here is that by starting all there perimeters in the same spot it creates weakness, but this is also a terrible start to the perimeter. I've tried upping the extra prime amount to a LOT (10 mm^3) and it had no effect at all, all the prints look like this. It really looks like under extrusion at the start, but there is no evidence of under extrusion anywhere else. Ideas on what needs adjusted here?

[burtoogle 514]

Hello @PaulK, assuming that you are using combing, set the max comb distance with no retract to something like 10. I think what you are getting there is unde-rextrusion after long non-retracted travel moves.

[PaulK 14]

6 hours ago, smartavionics said:

Hello @PaulK, assuming that you are using combing, set the max comb distance with no retract to something like 10. I think what you are getting there is unde-rextrusion after long non-retracted travel moves.

 

Yah, it is about a 2-3cm move (combing) to get to that point. I though that might be it too, so I put in a various values for "Retraction Extra Prime Amount" and it made no difference. Sigh. I  just kept reading "Extra Prime Amount", and ignoring the "Retraction"; of course there is no retraction in this case, hence why it made no difference. DOH. Some days I am just dumb. Or at least get a blind spot, when you get convinced you know what the problem is but not paying attention to the solution you think fixes it.

 

Max Comb Distance is excessively hidden, it isn't even in expert settings. I'm trying out 10 right now.

[burtoogle 514]

37 minutes ago, PaulK said:

Max Comb Distance is excessively hidden, it isn't even in expert settings

 

Yes, it really should have better visibility.

[PaulK 14]

Yes, limiting combing made it pretty much perfect, you'd be hard pressed to find the seam now. The strength is back too, not surprisingly. Thanks!