Pause at Layer extension - confusing behavior

[mkoic 2]

I'm experimenting with the Pause at Layer extension.  I'd like to be able to have a print pause so that I can insert a metal insert, then resume and have the insert captured.

 

I want to pause after completing Layer #20.  This happens to be at height = 4.1 mm.  I've attached an image of that point, as well as one of the next layer, #21 (height = 4.3 mm), and my settings for the Pause at Layer extension.  My gcode, .stl, and .3mf files are also attached.

 

One of the settings is "Redo Layers", and I selected to repeat 2 layers.

 

What I EXPECTED to happen is:

 

Layer 20 completes. (h=4.1 mm)

Pause is executed.

I press to continue.

Layer 19 is repeated (h=3.9 mm).

Layer 20 is repeated (h=4.1 mm).

All of the remaining layers are then completed starting with Layer #21 (h=4.3 mm).

 

What ACTUALLY happens is:

 

Layer 20 completes (h=4.1 mm)

Pause is executed.

I press to continue.

The tool paths for Layer 20 (or maybe its the paths from Layer 19) are repeated, BUT not at h=4.1 mm.  They are instead run at h=4.3 mm.

Layer 20 is then repeated AGAIN, this time at h=4.1 mm as expected.

Layer 21 is then executed at its correct height (h=4.3 mm).

 

The result of this is that I'm not getting the desired improvements to layer adhesion when the print resumes because it is run at the next layer height instead of repeating on the previous layer's height.

 

Test_TPU0_4sunfish.3mf test_TPU0_4sunfish.gcode sunfish.stl

Edited July 5, 2020 by mkoic

[GregValiant 1,248]

It doesn't work that way.  Cura will not allow itself or the plugin to crash into a part and it appears you want it to go where plastic has already been placed.  That qualifies as a Bad Thing because there just isn't anywhere for the plastic to go, and the head might move the print.

What the redo does is repeat the layers but continuing upwards.

(Cura layers start at 1 and Gcode layers start at 0.  The numbers below are Gcode layer numbers.)

Layer 18 at 3.9

Layer 19 at 4.1

;Pause before layer 20

Repeat Layer 18 at 4.3

Repeat Layer 19 at 4.5

Layer 20 at 4.7

Layer 21 at 4.9

etc.

I haven't used the redo.  Instead, I hand code an M221 S110 when the print resumes and increase the flow for the first layer after the pause.  The 2nd layer after the pause gets an M221 S100 to return the flowrate back to 100%.

[mkoic 2]

Thank you for the reply.

 

I do understand your point about not returning to an existing layer and that being a bad thing to do.  I’m printing TPU, though, and the layer after the pause is not bonding well at all with the previous layers, so I thought (not understanding the way the extension is supposed to work, I admit), that revisiting an existing layer would possibly work and cause no harm with the TPU having some give.

 

I am curious, however, why the display on my machine clearly showed z=4.3 the first layer after the pause, then it went back to z=4.1, and then back up to z=4.3?  From what you described, that should be impossible, shouldn’t it?

 

I do like your option of adding some code manually to increase flow.  For TPU on my machine, I already use a flow rate of 114%.  Would I do M221 S130 (or so) and then M221 S114 to return?  Or is the S100 100% of my set flow of 114%?

[GregValiant 1,248]

I see the Z numbers in the file match what you saw on the LCD.   The numbers I posted above were off the top of my head.  The numbers from the file are:

Layer 18 at 3.9

Layer 19 at 4.1

;Pause before layer 20

Repeat Layer 18 at 4.3

Repeat Layer 19 at 4.1

Layer 20 at 4.3

Layer 21 at 4.5

Maybe a moderator can comment on that.  It's not making a lot of sense to me.

Regarding the flow - the numbers you entered into Cura (114%) are used to calculate the E values that Cura put into the Gcode file.  So the E values are already at 114%.  When you manually add an M221 you will be changing those 114% values so go with the M221 S115 and then bring it back down with M221 S100.  I get good adhesion from PETG and PLA doing that even when the top surface cools down when I'm slow to get the printer started again.

 

Not to knock your design there, but I'd put a slot from the front ring to the tail hook attachment point.  You could wire them together and it would be a lot stronger than trusting the plastic to keep a strike from tearing out the hook.

[mkoic 2]

Thanks for the clarification on the flow setting.

 

 The design is actually from Thingiverse.  It makes use of some lure making hardware that can be purchased and that is supposed to drop right into the cutouts.  I agree with your comments, but I want to give that design a try since it wouldn’t require making my own wire structure.  It does look weak, though, and like you I thought a solid wire connecting things would be better.

 

I do hope a moderator will take a look at the discussion above and at the files I attached and provide some input on the behavior I’m seeing.

[GregValiant 1,248]

I suppose it will depend on what you're fishing for (and what actually hits!).  I've thought about making some lures but I'm in Florida now and mostly it's fishing with either cut bait or shrimp.  

[mkoic 2]

I ended up increasing flow to 115% for the first layer after resuming and also leaving the cooling fan off for the first two layers after resuming. That seems to have fixed my adhesion issues with the TPU.

 

Hopefully a moderator will still look at the layer issues discussed above with this extension.

[REZAL 0]

Hi guys..
I am new to 3d printer.

But right now I am trying this redo command.

In my opinion, the tool path just hoovering the previous layer to heat it, so the next layer can adhere better.

it is just an opinion and I haven't try it yet.

I will try it soon and update.