[ADDED] purge walls for dual printing (and singel)

[BaronWilliams]

You don't need different scripts for the different extruders. Use the same script for both. A tool change occurs on each layer, so as long as both extruders are using the same tool change script and drawing their lines in the same place, it will be fine.

A tool change doesn't trigger the tool change scripts on each layer. It is in constant. Look at the preview in Simplify3D. It shows you that it is inconsistent.

My tests in Simplify3D 2.2.2 show that the first and last layers get drawn TWICE in this case, so we get 2 tool changes for the 1st layer, not 1. It's buggy. Try offsetting the two G-codes just enough to see each process's separate line and where they intersect with each other. The object builds with the first two processes making a single line at the same Z level, from there on, each line is printed every other layer, or 1 tool change per layer, and then again near the last layer, 2 again are printed at the same Z level. So it switches between 2 tool changes per layer, to 1 tool change per layer, and then back to 2.

It should be doing 2 tool changes per layer, not 2, then 1, then 2!

It's tool change script triggering logic is all goofed up. But drawing two lines in the same location twice doesn't cause much of a problem, but it can contaminate the extruder's nozzle with the other extruder's filament as the filament bunches up as it's printing over a layer that has no space for it to print because it's already filled in.

A future release of Simplify3D is bound to fix this weird tool change script triggering behavior. So don't rely on this weird behavior not changing. It most likely will change.

[BaronWilliams]

Here's a picture to illustrate the bug where the first and last tool change scripts are done with 2 changes per layer, not 1 as the others are. I zoomed in to show just the purge walls created by my G-code. I specifically made the walls overlap some so that you can see this problem easily.

On the right is a line that is printed with process 1. The left is process 2. Here's the tool change G-code I used to show this buggy result in Simplify3D:

Process 1 Tool Change G-code Script:

Code: Select all

G1 X-10 Y-70 F1200 ; Move to the start position of a new line
G1 X-50 Y-70 E2 F1200 ; The value of E is changed by Simplify3D, but need to be there to print a line

Process 2 Tool Change G-code Script:

Code: Select all

G1 X-20 Y-70 F1200 ; Move to the start position of a new line
G1 X50 Y-70 E2 F1200 ; The value of E is changed by Simplify3D, but need to be there to print a line

In the Simplify3D 2.2.2 screen shot above you can clearly see that 2 tool change scripts are run at the first and last layers, causing 2 lines to print a portion in the same exact location. All of the other tool changes happen only 1 time per layer. It's all goofy. We should get 2 tool changes per layer, not 2, then 1, then 2.

The problem is that process 1 changes behavior. Process 2 has consistent behavior. But in my opinion both are not correct. We can see that the lines made by process 2 on the left print every other layer. Process 1 is printing lines every layer for the first 2 layers, and then every other layer, and then again every layer for the last 2 layers. Both process 1 and process 2 should be consistent, but they aren't. And both processes should print this G-code EVERY LAYER, not every other layer. It's all messed up.

[Ola]

Sorry, does not work in real life. I have tried. You cannot control in what order the nozzle moves from one to the other, that depends on… who knows what.
It changes when you change the placement of the parts on the print table. It might change depending on the alphabetical order of the processes, (?) I have not been able to figure this out.
It is a hassle.
What is needed is a purge wall option like the one Makerboot have, to guarantee that the nozzle is primed on the purge wall IMMEDIATELY before printing the part, and that this happens after EVERY tool change.
It should be a simple thing to add.

Well now, I have done some investigation and found a way.
The simple solution is of course for S3d to add a proper purge wall, but that might just happen 2019 or so.
In the meantime, this is one way of using sacrificial objects that might work:
Object to print: “B” with support “Bs” using two different materials, dual nozzles, and freshly purged.
Sacrificial parts “A” and “C”(with their supports As and Cs).
Part A and C must in some important aspects be identical to B. In fact, if they all are identical this process will work, but in order not to waste time and material there are some dimensions that can be altered: The Z-dimensions have to be identical. The X- and Y-dimensions can be minimized. This can be done by object scaling in the model settings. (Another way might be to let the A and B parts be without infill, but that I have not tried yet. Yet another way is to trim them with other tools).
The goal is to print “B” and “Bs” with freshly wiped nozzels.
Place the parts so that printing starts at A, then moves to B and C. If needed (always?) use process layer settings “choose start point…” with suitable input, so that nozzle goes to A directly after standard wiping off of the table.
Nozzle will move like this: A-B-C-Cs-Bs-As.
B will always be printed after sacrificial printing of A.
Bs will always be printed after sacrificial printing of Cs.
When changes occurs in support height (as it does automatically) the changes happens to all parts simultaneously, and the pattern is kept. If the support part heights would be different, the pattern would change and tool change from Bs to B or from any other combination to sacred part B would occur, and mess things up. The nozzle moving pattern would change.
Keep in mind that A and C must be large enough to contain same number of perimeter shells as part B, and any supported overhang must be large enough for support to actually be printed under it.

[Vol]

Well now, I have done some investigation and found a way... (Thu Feb 12, 2015 9:00 am)

Thanks Ola, that is the best and simplest method I have found to get by untill Simplify3D implements screens as a feature. I have made a very simple screen that is easy to re-size in simplify if anyone is wanting to try it.

Screen part STL, some pictured instructions, and Ola's method can be found here: http://www.thingiverse.com/thing:689074

Thanks Ola!!!

[dennisjm]

Well now, I have done some investigation and found a way.
The simple solution is of course for S3d to add a proper purge wall, but that might just happen 2019 or so.
In the meantime, this is one way of using sacrificial objects that might work

That pretty much sums up my experience. "might" is the key word. I've got dual extrusion to work well on some objects but then I try a different object and find the same settings didn't work the same... e.g., incorrect tool order resulting in blobs on the target object. Also, it's painful to try and set this up for a print. In the mean time I just use a different slicer if I have to dual extrude. Unfortunate but reality... until hopefully not as long as 2019

[Ola]

Well now, I have done some investigation and found a way... (Thu Feb 12, 2015 9:00 am)

Thanks Ola, that is the best and simplest method I have found to get by untill Simplify3D implements screens as a feature. I have made a very simple screen that is easy to re-size in simplify if anyone is wanting to try it.

Screen part STL, some pictured instructions, and Ola's method can be found here: http://www.thingiverse.com/thing:689074

Thanks Ola!!!

Dont forget that S3D messes up the sequence easily if not the 3 objects have EXACTLY the same height for the support.
Part of the problem is that S3D is trying to be more intelligent then what is called for... different support height will create different nozzle paths.

Very important point, please concider this for your thingiverse thing...

[S3D-Jason]

As of version 3.0, Simplify3D now includes an ooze shield that will automatically purge each extruder when performing dual extrusion prints. It also does a great job protecting your parts from defects.

This video explains the new dual extrusion options in more detail: https://www.youtube.com/watch?v=qPufaJhyqME