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I've been trying to change to the latest Cura (v2.4) from the older v15.04 (I'm sure there's a good story about why they reset the numbers).

There's an annoying behaviour in my prints now, and I can't track down what is happening. Everything goes fine, but during the print (maybe mostly near later layers) there are these moments when the print head doesn't move with the normal 30-50 mm/second, but perhaps 1-2 mm/second.

Watching the filament closely, it appears to retract filament at that moment, then the head moves painfully slowly around the part. Then 10 seconds later it goes flying around again.

Can't see a "print speed during retraction" setting. I see a speed at which the filament is retracted setting - I'm guessing that's unrelated.

I'm worried these frequent slow move sections are having two effects:

  1. The hot print nozzle sitting on the part is deforming the surface features;
  2. The hot print head is overheating the filament feeding into the nozzle and I get jams or sometimes swollen filament that won't go back into the nozzle as it tries to proceed further, causing a jam.

Any idea what makes these super slow movements? The older Cura never caused any of them.

I'm using a Monoprice Select mini printer, with six months of good results before this showed up, and only with G-codes created with new Cura 2.4.

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  • $\begingroup$ Doing a test print - of a small section of a prev model. I see those painfully slow moves may be between layers? A layer seems to finish nice and quick, then the slow snail-like move across the model, then another fast layer happens. Looking for related param's to try. $\endgroup$ – RossGK Mar 18 '17 at 19:26
  • $\begingroup$ Can you paste or link the gcode for the layer where this occurs? $\endgroup$ – Davo Mar 21 '17 at 20:48
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    $\begingroup$ With further testing, I've found this issue relates to retraction, in that if I turn off retraction, the slow-move goes away. Of course, then I have stringing to clean up afterwards, but it stops the painfully slow moves. I need to dig into what element of retraction settings would cause the very slow moves still. Suggestions welcomed. (looking at min layer time as sugg by tjb1 below) $\endgroup$ – RossGK Mar 22 '17 at 15:21
  • $\begingroup$ Retraction speed would affect the move time. $\endgroup$ – tjb1 Mar 22 '17 at 19:28
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Are the layers where this is happening smaller than previous layers? Many slicers have a minimum layer time setting where if the layer takes less than X time, it will either slow the layer down or possibly pause until the time is reached.

This can be useful to allow the previous layer to cool down and harden up a bit before more hot plastic is added. If you're not having issues cooling the print then you could disable this. I've only ever used Slic3r, KISSlicer, and Simplify3D so I'm not sure where the setting would be in Cura but those slicers all had/have the option.

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  • $\begingroup$ It is the case that some of the times I've noticed the slow movement has been on smaller layers - I'll check into the minimum layer time settings. Think I've seen it on large layers too, while moving between areas. Will investigate further - thx for the hint. $\endgroup$ – RossGK Mar 22 '17 at 15:23

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