simple print mission, help!

Hello Reprapers,

I am not the expert in Slic3r or print orientation. So need your help to accomplish my simple task.

I need to print as basic as two layers of a rectangular shape. I have played around with slic3r and was able to print two layers but not in the
orientation needed. For research purposes, i need to have both layers (top of one another) to have the same print path.

The problem im facing is, when the printer finish with the first layer ( 180 degrees ) it would start building the second layer (SL) where it left the first one.
Meaning a reverse print. I want the SL to have the same print path as the FL. i.e same start and end points.

in other words, need both layers to be identical.

Any help with how to go about doing that is appreciated...
thanks,

I have this strange feeling of deja vu...

mturson,

You have asked essentially the same question several times in the last few months, and each time it has been answered the same way:

Common slicing software deliberately rotates successive fill layers to achieve a strong solid build; having successive layers cross each other produces a good 3-dimensional near-homogeneous matrix, while you are trying to deliberately force parallel touching threads. You are trying to print something that standard slicing software tries to avoid.

The simplest way will be to use the slicing software of your choice, then manually edit the resulting G-Code file to print the same layer twice - that is, delete the second and subsequent layers as created by your slicing software, and then copy and paste the first layer after the Z-axis shift. You may need to make sure you insert a couple of Move commands to force the print head back to the same actual (x,y) coordinates at the start of each layer - otherwise, the second layer may start where the first layer finishes.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Maybe time to write a simple parametric g-code generator?

1. I fail to understand why someonne must ask the same question again and again.
2. I fail to understand why anyone would want to have the next layer printed the same way as the first - there is a very good reason why it works that way...
3. I fail to understand why it would be so damn hard to print a single layer and then to print the same again after adjusting the print height....

In all that time you asked the same question again and again you could have used a 3Doodler and created your square by hand

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Downunder35m
2. I fail to understand why anyone would want to have the next layer printed the same way as the first - there is a very good reason why it works that way...

For what it's worth - in one or more of their previous posts, the OP has explained they are trying to do some sort of research into inter-filament bonding, and they believe they need identical layers for that purpose. I can't comment on the practicality or need of their research, other than to reiterate that typical 3D printers with typical slicing software and firmware don't print that way by default, for very good reasons!

(The theoretical inter-filament bond strength of adjacent parallel layers is of very little practical interest to hobbyists if you can avoid the limitation altogether using standard printing practices. But who knows - maybe the research will lead to new insights into the behaviour of fused filament deposition, and better, faster 3D printers in the future?)

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

The purpose of having both layer identical is to have a quantitative interfacial force measure of the two layers. I agree that cross layers would result in stronger build. but
improving the bonding strength between parallel layers will automatically increase it in the cross layers.

Sorry for repeating myself, but im not the g-code kinda person. If you have a good reference to go to for commands and such plz let me know.
I was thinking there is an easier way to achieve that within the software interface.

Ill give the g-code a good manual edit and go from there. Hope no more deja vu ..

Quote
Downunder35m


In all that time you asked the same question again and again you could have used a 3Doodler and created your square by hand

lol shouldve done that long ago... brilliant

Why not post the G-Code file you have - some kind soul can probably show you how to edit it manually.

It's not "rocket science" to understand the G-Code that your slicing software generates - just open it in the text editor of your choice, and see the official reference here: [reprap.org]

If you examine your G-Code file, you will see that there are only a few commonly used commands, such as the following, so it isn't too hard to manually edit or write a G-Code file to do what you are after.


G-Code | Command Name | Example Usage
G1 | Move | G1 Xnnn Ynnn Znnn Ennn Fnnn Snnn
G21 | Set Units to Millimeters | G21
G28 | Move to Origin (Home) | G28 (Go to origin on all axes) | G28 X Z (Go to origin only on the X and Z axis)
G90 | Set to Absolute Positioning | G90
G92 | Set Position | G92 X10 E90
M104 | Set Extruder Temperature | M104 S190
M106 | Fan On | M106 S127
M107 | Fan Off | M107
M109 | Set Extruder Temperature and Wait | M109 S185
M140 | Set Bed Temperature (Fast) | M140 S55
M190 | Wait for bed temperature to reach target temp | M190 S60
M82 | Set extruder to absolute mode | M82
M84 | Stop idle hold | M84

Edited 1 time(s). Last edit at 10/22/2015 10:26PM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

How are you planning to test the layer-to-layer bond strength?

Remembering that each layer is itself made up of numerous parallel "filaments", when you try to separate two layers, it will probably tend to tear across the layers as well.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Quote
julianh72
Why not post the G-Code file you have - some kind soul can probably show you how to edit it manually.

It's not "rocket science" to understand the G-Code that your slicing software generates - just open it in the text editor of your choice, and see the official reference here: [reprap.org]

If you examine your G-Code file, you will see that there are only a few commonly used commands, such as the following, so it isn't too hard to manually edit or write a G-Code file to do what you are after.



M84 | Stop idle hold | M84

here is the shape i want to print.

So, now take a look at your G-Code file, and understand what it does:

Lines 1 to 7 are introductory comments
Lines 8 to 20 get the machine ready for printing
Line 21 moves the printhead to a z-height of 0.2 mm
Lines 22 to 266 print the first layer by shifting the x and y coordinates and extruding as you go
Line 267 shifts to a z-height of 0.4 mm
Lines 268 to 513 print the second layer
Lines 514 to 516 shut the printer down
Lines 517 to 638 are comments, describing the machine and slicer settings etc

So, in principle, delete lines 268 to 513, and replace with a copy of lines 22 to 266 - voila!

Note that your slicing software (Slic3r 1.1.7 according to Line 1) has probably set-up the first layer to be extruded “generously”, so that it can be “smooshed” as a contiguous layer into the bed-plate. You may need to tinker with the extrusion rates to get the right amount of filament laid down, to avoid over-extrusion.

Hope this helps!

“Give a man a fish and you feed him for a day; teach him how to fish and you feed him for life.”

Edited 1 time(s). Last edit at 10/23/2015 07:02PM by julianh72.

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

Quote
julianh72
So, now take a look at your G-Code file, and understand what it does:

Lines 1 to 7 are introductory comments
Lines 8 to 20 get the machine ready for printing
Line 21 moves the printhead to a z-height of 0.2 mm
Lines 22 to 266 print the first layer by shifting the x and y coordinates and extruding as you go
Line 267 shifts to a z-height of 0.4 mm
Lines 268 to 513 print the second layer
Lines 514 to 516 shut the printer down
Lines 517 to 638 are comments, describing the machine and slicer settings etc

So, in principle, delete lines 268 to 513, and replace with a copy of lines 22 to 266 - voila!

Note that your slicing software (Slic3r 1.1.7 according to Line 1) has probably set-up the first layer to be extruded “generously”, so that it can be “smooshed” as a contiguous layer into the bed-plate. You may need to tinker with the extrusion rates to get the right amount of filament laid down, to avoid over-extrusion.

Hope this helps!

“Give a man a fish and you feed him for a day; teach him how to fish and you feed him for life.”

Thank you for breaking it down to me. I was able to print the two layers as intended.
However, as you mentioned, the first layer was printed more generously than the second and I was able to see that in the gcode.
Now I have two issues:
1- Total thickness of the sheet required is 0.6 mm- each 0.30 but the total thickness after the print comes to roughly 0.28mm
2- The first layer still turn out to be 100% thicker.

any suggestion!
Thanks

You'll need to insert this right after g92 E0 on line 110, make a new line:
G1 Z0.600 F7800.000 ; move to 2nd layer

It will go to the second layer height. Without this it will try to squeeze the filament in the same place where there's already a layer printed.

You may also want a retraction if the nozzle is leaking filament. Half of the retraction is already there, so the gcode you have now is actually under extruding when it starts the second layer.
replace G92 E0 on line 110 with this:

G92 E0 ; reset extruder position
G1 F1800.000 E-1.00000 ; retract
G1 Z0.600 F7800.000 ; move z axis to second layer
G92 E0 ; reset extruder position

Then the next bit will move to the start, unretract and continue printing the second layer:
G1 X112.200 Y84.700 F7800.000 ; move to beginning of layer without extruding
G1 E1.00000 F1800.000 ; unretract

Quote
imqqmi
You'll need to insert this right after g92 E0 on line 110, make a new line:
G1 Z0.600 F7800.000 ; move to 2nd layer
G1 E1.00000 F1800.000 ; unretract

Been working on the code, but printer having an issue now. extruding imbalance

By default, Slic3r will try to extrude a "generous" amount of filament for the first layer, so that it will create a fully contiguous sheet when it is "smooshed" into the print bed. Second and subsequent layers are less generous, as the intent is to just get the parallel filament threads to touch, not to fully fill the space.

The actual thickness of the first layer will depend upon the Z0 gap you have between the print bed and your extruder height when Z = 0 mm (should typically be about the thickness of a sheet of paper), so printing the first layer at Z = 0.3 mm should actually print a layer which is "0.3 mm plus a bit" thick. (The print bed is actually "a bit" lower than Z0.)

Printing the second layer at Z = 0.6 mm should be exactly 0.3 mm above the first layer (assuming you have your Z axis properly calibrated). Slic3r will generally assume the second and subsequent layers are printing onto previously printed layers, with precisely known Z steps, so it doesn't need to be as generous with the extrusion rate to "overfill" the Z0 gap.

To get two identical layers, you may need to print the second layer allowing for the Z0 gap (i.e. set the second layer to a Z height of "0.6 mm plus a bit" rather than 0.6 mm, where "a bit" is calibrated to be equal to your Z0 gap), and you may want to modify the extrusion rate and print head travel speeds to be the same us Slic3r generated for the first layer. Your first layer seems to print at an extrusion rate of F1200, but the second layer is printed at F900 - only 3/4 of the amount of extruded filament as for the first layer.

Because you are trying to do something which Slic3r isn't designed to do, you'll probably need to experiment with the G-Code to achieve two identical layers (identical in layer thickness, extrusion rates, travel speed, etc).

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]