Slicer tips, discussions, questions & answers

iLikeWaffles · 17-04-2021 1:27am #1

I figured there will be lots of questions relating to slicer settings being asked by newer users, including myself. So there might as well be a thread for them all.

Perhaps over time it can turn into a sort of guide with useful tips you might not know. Posts could be reported and edited to the top post if a mod would not mind maintaining the thread so participants and fresh views can find them easily if the thread gets too big to navigate.

So I'll start it off with a question.

Q. In Cura Slicer is it possible to print slice 1- 5 and end or more appropriately print a section, i.e. start at slice 95 and end at 200, for instance if your gcode has 400 slices (see attachment).

Small tip I seen somewhere is orientating the print under the bed and placing a section you want to test print above the bed in Cura. But this only works for certain geometries and if you want to test for accuracy randomly stopping will not be accurate.

stevexo · 17-04-2021 1:37pm

iLikeWaffles wrote: »

So I'll start it off with a question.

Q. In Cura Slicer is it possible to print slice 1- 5 and end or more appropriately print a section, i.e. start at slice 95 and end at 200, for instance if your gcode has 400 slices (see attachment).

I had this very same question.
I was monitoring a print when at Z height 17 the layers started to separate from the print.
Everything up to height 17 was perfect so instead of wasting that print, i decided I wanted to keep it and continue from this position, gluing the end results together.
I found a program called Slic3r previously that can be used to nicely cut stl files at a certain position into 2 objects on any of the axis.
This guy was on TikTok and his youtube channel goes into how to use Slic3r.
This is the video I got all I needed from.

So I loaded up the file, cut the object at Z 17 and selected to only keep the top new object.
Saved this as an stl and loaded back into Cura.
I could then apply my profile and save to the micro sd card for printing.
The print started exactly where I needed it to but at the time I had other issues from the actual physical setup of the printer that caused me to stop again at layer Z 9 this time.
I decided I had to figure these out before wasting any more time.

iLikeWaffles · 18-04-2021 3:49am

stevexo wrote: »

I had this very same question.
I was monitoring a print when at Z height 17 the layers started to separate from the print.
Everything up to height 17 was perfect so instead of wasting that print, i decided I wanted to keep it and continue from this position, gluing the end results together.
I found a program called Slic3r previously that can be used to nicely cut stl files at a certain position into 2 objects on any of the axis.
This guy was on TikTok and his youtube channel goes into how to use Slic3r.
This is the video I got all I needed from.

So I loaded up the file, cut the object at Z 17 and selected to only keep the top new object.
Saved this as an stl and loaded back into Cura.
I could then apply my profile and save to the micro sd card for printing.
The print started exactly where I needed it to but at the time I had other issues from the actual physical setup of the printer that caused me to stop again at layer Z 9 this time.
I decided I had to figure these out before wasting any more time.

Good to know for future but this would not apply to the print I'm looking to do. How far along has that slicer software come since the video. Not exactly confident about using it if it doesn't work well!

iLikeWaffles · 18-04-2021 4:07am

I'm always looking at a print and thinking this is not efficient. For instance when printing walls or finishing a layers infill it will start at some arbitrary point then move to another arbitrary point in the print, if you multiply all of these wasted movements your print time is taking longer than it should.
I've not found a way to optimise travel time where there is no wasted movement or it is completely removed, probably impossible for some prints anyway. For the sake of example: if you are to print an S it shouldn't start at the North position each layer it should interchange from North travel South finish the layer and start at South of the S move North etc, some prints might not have any choice in wasting travel time by not printing in a particular spot because of its size or shape but there are 2 experimental features in Cura that can help with print time.

They are infill travel optimisation and optimize wall printing order, the later will finish the walls of separate objects (or gaps/holes in a single object) on the bed first before moving to the next. This can have a surprising reduction on print time as wall 1 of each object will not be printed first and instead walls 1-3 will be printed for the first object then the 2nd, 3rd etc. So the travel time will be reduced.

AirBiscuit · 19-04-2021 11:24pm

Just messing around with an idea that I would otherwise make with plywood because I don't have a 3D printer of my own.
In cura, is there a way to specify different thicknesses for different walls? The outer walls and the rectangular cutouts don't matter, but the round holes need a bit of thickness to them like in the picture because they'll have potentiometers secured on them with a nut (or the holes will be tapped if PLA is strong enough to thread).

iLikeWaffles · 20-04-2021 12:49am

AirBiscuit wrote: »

Just messing around with an idea that I would otherwise make with plywood because I don't have a 3D printer of my own.
In cura, is there a way to specify different thicknesses for different walls? The outer walls and the rectangular cutouts don't matter, but the round holes need a bit of thickness to them like in the picture because they'll have potentiometers secured on them with a nut (or the holes will be tapped if PLA is strong enough to thread).

Would be best to edit the 3d render, wall thickness is a global setting for all parts of a print. You would have to edit the stl file in Blender or another program that can edit stl files and resize the holes by x amount to get different sizes if I understand correctly. Cura is just for exporting/saving the code the 3d printer understands (x,y,z coordinates, temperature information or running scripts while it prints)

There is a way to mark something and have custom settings for that part so it could be possible to have different wall thickness to print to a specific spec but if it is to resize something rather than being for a specific reason then edit the stl before importing in Cura.

Skip to 2:03

https://www.youtube.com/watch?v=su_m5zV9rvA

AirBiscuit · 20-04-2021 1:23am

iLikeWaffles wrote: »

Would be best to edit the 3d render, wall thickness is a global setting for all parts of a print. You would have to edit the stl file in Blender or another program that can edit stl files and resize the holes by x amount to get different sizes if I understand correctly.

Had realised this shortly after posting, looks like it's time for more learning. Struggled to model it in FreeCAD, but had an even worse time using parts of blender than I haven't ever used after a decade of singular focus on subdivision mesh modelling for games where the golden rule was avoid ngons and use quads.
EGSu2Rg.png?1

I have no idea how to tidy this up further (after and before). Inset doesn't work for the hole edges so I forget how to make a wider ring. It looks all sorts of wrong, but seemingly is OK by Cura

iLikeWaffles · 20-04-2021 2:06am

AirBiscuit wrote: »

Had realised this shortly after posting, looks like it's time for more learning. Struggled to model it in FreeCAD, but had an even worse time using parts of blender than I haven't ever used after a decade of singular focus on subdivision mesh modelling for games where the golden rule was avoid ngons and use quads.
I have no idea how to tidy this up further (after and before). Inset doesn't work for the hole edges so I forget how to make a wider ring. It looks all sorts of wrong, but seemingly is OK by Cura

Yeah Blender is a nightmare, but it is powerful. With all vertices selected try mesh>clean up> ???

oscarBravo · 20-04-2021 9:46am

That looks like a design that could be run up quickly in FreeCAD (granted, I've been using it for a couple of years now) - in Part Design, create a body, sketch on the XY plane, draw a rectangle, pad to the required thickness, another sketch on the top surface, draw the two rectangular and all the round holes, and pocket through all. What did you struggle with?

If you did want a different wall thickness for the holes, I'd go with CHEP's advice from the video posted, it's actually pretty straightforward to do.

Doge · 20-04-2021 10:35pm

How to show the Current Layer printing on the LCD Screen of your 3D printer:

Cura -> Extensions -> Post Pocessing -> Modify G Code -> Display Filename and Layer on LCD

iLikeWaffles · 21-04-2021 2:17am

Doge wrote: »

How to show the Current Layer printing on the LCD Screen of your 3D printer:

Cura -> Extensions -> Post Pocessing -> Modify G Code -> Display Filename and Layer on LCD

Wish the filename's would scroll it's like Russian roulette trying to choose a file especially when Cura appends files with CE3_

Is that 'initial layer number' an offset so it will display layer 0 as 1 or 1 as 2 if you enter 1 there.

iLikeWaffles · 21-04-2021 4:08pm

By default the infill prints at 45°. Not sure why, but logically this would make prints not as strong as they would be when printed parallel to a wall, for instance on a rectangle or square print.

infill gear icon > search "infill" > "infill line directions"
Also here an x, y infill offset might come in handy for future prints.

When the setting is enabled direction can be entered between the brackets [x,y]

AirBiscuit · 25-04-2021 9:44pm

Let's talk infill and strength: What would give the best strength for a thin rectangular surface (like the screenshot)? What would give the best strength for a sphere?
The settings on Cura seem to vary wildly in terms of print time, but don't really give an comparison of strength between every setting on the tooltipm, only grouping them into "reduced material cost", "fully printed every layer", "more equal strength distribution"

eEKtkZI.png?1

iLikeWaffles · 25-04-2021 10:35pm

The best infill would be a hexagon as it uses the least amount of material to hold the most weight; that's why bee's build honeycomb in a hexagon shape as well as it being a perfect size for their eggs and honey. Triangles are more efficient I would imagine for printing and offer the same or better strength (6 triangles making up the shape of a hexagon). I don't bother with any other infill other than triangles myself. PLA is not too strong anyway probably same strength as soft wood.

oscarBravo · 26-04-2021 10:15am

It's also important to ask: how strong do you need it to be? As in, what loads is it likely to carry?

A YouTube channel that's well worth a look if you're interested in the strength of 3D-printed parts is CNC Kitchen. In my experience, unless the part you're designing is explicitly load-bearing, it's just not something you need to worry too much about.

For an instrument panel like the one shown, I'd print three top and bottom layers, three walls and 20% "lines" infill. The infill acts like the lightweight filler material in a composite sandwich. It gives strength to the walls by giving them some physical support behind them, and stiffens the top and bottom layers by basically tying them to each other.

This goes back to something I mentioned before about iterative design and prototyping: the best way to know whether a given suite of settings produces a strong enough part is to print it and see.

iLikeWaffles · 05-05-2021 8:23pm

Updated firmware to Marlin v2.x on the Ender 3. Prints kept starting way too close to the bed, the Z axis was sitting too close to the bed when printing only; when levelling sitting at a different height. There is a setting in Cura for applying Extruder offsets to gcode in printer settings. Unchecking this and prints are just fine. So I can only assume that the new firmware is now accounting for this offset as prints with the Cura setting disabled print as if it was enabled; pre update gcode won't stick as the nozzle would be offset twice, one in the gcode and the other in the firmware.

What I'm wondering is has anyone else come across this issue? And does anyone have the extruder offset setting enabled in Cura with the latest Marlin v2+ firmware and have not seen nor heard of the issue?

AirBiscuit · 06-05-2021 12:07am

iLikeWaffles wrote: »

Updated firmware to Marlin v2.x on the Ender 3. Prints kept starting way too close to the bed, the Z axis was sitting too close to the bed when printing only; when levelling sitting at a different height. There is a setting in Cura for applying Extruder offsets to gcode in printer settings. Unchecking this and prints are just fine. So I can only assume that the new firmware is now accounting for this offset as prints with the Cura setting disabled print as if it was enabled; pre update gcode won't stick as the nozzle would be offset twice, one in the gcode and the other in the firmware.

What I'm wondering is has anyone else come across this issue? And does anyone have the extruder offset setting enabled in Cura with the latest Marlin v2+ firmware and have not seen nor heard of the issue?

Upgraded mine to 2.0.8 today as well, first print was too close to the bed to the point the skirt craped the bed plastic.

Selected what I thought was the Chep bed level non-print version from the SC card, and in preparation I lowered all the springs by about a quarter of a turn each. Turns out it was the printing version, and whichever way I managed to twist all the levelling dials was just right.
If it's the stock(??) bed with the removable plastic plate, I think it warps relatively easily: Before this, no matter what way I tried the right side of the bed would be far too close to the nozzle, but the corners were fine.

iLikeWaffles · 06-05-2021 11:04am

AirBiscuit wrote: »

Upgraded mine to 2.0.8 today as well, first print was too close to the bed to the point the skirt craped the bed plastic.

Selected what I thought was the Chep bed level non-print version from the SC card, and in preparation I lowered all the springs by about a quarter of a turn each. Turns out it was the printing version, and whichever way I managed to twist all the levelling dials was just right.
If it's the stock(??) bed with the removable plastic plate, I think it warps relatively easily: Before this, no matter what way I tried the right side of the bed would be far too close to the nozzle, but the corners were fine.

Did you manually level the bed with a piece of paper, was this spot on? The nozzle then moved closer to the bed when printing even though it was already levelled. That Chep gcode for leveling and the print was saved for an earlier version of Cura like 2.9 iirc. Was the gcode working before updating the firmware. This is because in Marlin v0.0.5 there was no changes to the Z offset which Cura accounts for at default settings, the gcode is accounting for it but the new firmware does now too, was looking for it in the source code of the firmware but it is well hidden. Its not particularly the gcode, it is the firmware accounting for a Z offset but the older gcode does too.

I ended up doing my own gcode because it is very slow to use that Chep one.

The one I am using at the minute has many positions so takes a little longer to level compared to that Chep one. It accounts for the uneven spots on my bed, of which I have found 2 by manually moving around XY.
I work from one of the uneven spots as a base level and double side a piece of paper for the corners as a base. I then adjust so the centre and surrounding the centre is about average. The only thing you can do with even spots is try to average the differences out which is what a tramming mesh a.k.a auto bed level does. Prints are never really printed at the sides or corners so half or less of your bed is only really used the majority of the time.

With your right side being uneven as you say that could be your Z tension on the right where you adjust the nuts. Mine is fairly parallel to the bed. It is not really levelling the bed, the whole printer can be unlevel, it can print at an angle of 15° what's important is that the Z and Y are parallel. The Z axis needs to be parallel to the Y (Bed) it being called levelling confuses things. The process of levelling is what is called tramming.

Any and all of your gcode already on your SD card will need to be re-sliced and saved with the Z offset unchecked in Cura for Marlin v2. Preferences>Configure Cura>Printers>Machine Settings

To give an idea here's a single pass of the code I wrote for levelling, which sends messages to the LCD also.

; Bed levelling Ender3 04/05/2021

G90 ; absolute position

G1 F2500 ; extruder lowering speed to check the level
G0 F8000 ; speed of XY movement for Position's

M117 Moving To Home ; LCD message
G28 ; Auto Home
G1 Z0 ; prime Z axis to check there is enough spacing
M0 Click to begin; Pause and wait for user to begin level procedure

; bed pattern #1: 6, 1, 2, 4, 3, 5 - start on uneven spot

M117 Moving to pos 1 of 6
G1 Z5 ; Lift Z axis
G0 X82 Y165 ; Move to Position 6, my uneven spot
G1 Z0 
M0 Click to continue ; Pause and wait for user input

M117 Moving to pos 2 of 6
G1 Z5 ; Lift Z axis
G0 X29 Y35 ; Move to Position 1
G1 Z0
M0 Click to continue; Pause and wait for user input

M117 Moving to pos 3 of 6
G1 Z5 ; Lift Z axis
G0 X199 Y205 ; Move to Position 2
G1 Z0
M0 Click to continue; Pause and wait for user input

M117 Moving to pos 4 of 6
G1 Z5 ; Lift Z axis
G0 X29 Y205 ; Move to Position 4
G1 Z0
M0 Click to continue; Pause and wait for user input

M117 Moving to pos 5 of 6
G1 Z5 ; Lift Z axis
G0 X199 Y35 ; Move to Position 3
G1 Z0
M0 Click to continue; Pause and wait for user input

M117 Moving to pos 6 of 6
G1 Z5 ; Lift Z axis
G0 X114 Y120 ; Move to Position 5
G1 Z0
M0 Click to End; Pause and wait for user input

;----------FINISH-----------

G28; ; Auto Home
M84 ; disable motors and finish

Slicer tips, discussions, questions & answers

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