Big Z-lifts during print

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Tutorius
Posts: 19
Joined: 25 Aug 2017, 13:43

Big Z-lifts during print

Post by Tutorius »

Hi,

i am using the new release of KISSlicer 1.6, and have problems on some models.

I have tolde the nozzle to lift before a move up 0.3mm, and it does that on most moves.

But some moves act different, the nozzle is raised by a bigger value, the nozzle remains for a second or two at the high place, then it is lowered again and the print continues.

That has a bad result, cause my cooling-system is raised, too, and the printed PLA does not get the air as it should.

I have added tow pictures, taken from Repetier-Host, to show a normal move and a bad move.

Any suggestions? Is that a feature that i need to disable? Or is that a bug?
layernormal.jpg
layernormal.jpg (7.23 KiB) Viewed 1231 times
layerwhat.jpg
layerwhat.jpg (7.67 KiB) Viewed 1231 times
Thanks for your suggestions and answers!

Edit: Have found the GCode

Code: Select all

; Post-layer lift
G1 X99.176 Y103.043 Z8.45 E0 F210
; END_LAYER_OBJECT z=3.700
; BEGIN_LAYER_OBJECT z=3.950 z_thickness=0.250
; Blending Fan to Cool (98.5% blend)
The head is not lifted to 4.25mm, it is lifted to 8.45mm, that is 4.2mm too much ...
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pjr
Posts: 692
Joined: 05 May 2015, 10:27
Location: Kamnik, Slovenia

Re: Big Z-lifts during print

Post by pjr »

This normally happens when the layer is printed too quickly. and then has to pause at the end of the layer.

What is your Settings/Material/Min Layer time set to?

Peter
Tutorius
Posts: 19
Joined: 25 Aug 2017, 13:43

Re: Big Z-lifts during print

Post by Tutorius »

Thanks for your answer. This helped me finding the solution.

The minimum time is set to 6 seconds, but i thought the slicer would print slower to achieve the longer printing time, not to lift the nozzle 4mm and stay there for an amount of time...

I have found the "guilty" parameter for this now. It is the parameter "Cool" in flow adjust (Material-settings). I had to rise this value. The slicer "thought" that it could not cool that amount of material and made this pause on some layers.

I think that i will do some tuning with the parameters, but on the other side, the parameters for one-loop-prints as i do here are a bit special, perhaps just disable this feature by rise this value to 100 or so...
params.jpg
params.jpg (57.56 KiB) Viewed 1214 times
User avatar
pjr
Posts: 692
Joined: 05 May 2015, 10:27
Location: Kamnik, Slovenia

Re: Big Z-lifts during print

Post by pjr »

Yeah, KISS will slow down the layer according to Flow Adjust/Min, but after that, it will list and pause.

FWIW, my settings, PLA:

Min Layer = 1s
Min = 0.25mm^3/s (140 E Steps/mm)
Max = 10mm^3/s
Cool = 0.75mm^3/s (although I think this could be a little higher)

The cool parameter is for un/partially supported extrusion.

Peter
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