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

[Ola]

Dual printing requires a purge wall function so that when changing tools, the new tool starts on a purge sacrificial wall before going to the actual print.
Please look at Makerboot for an excellent example.

[BaudR8]

I don't have any dual extruder printers, but I saved this image a while back another forum poster uploaded that makes use of sacrificial parts for purging purposes:

[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.

[JoeJ]

You could do this by adding 4 lines to your tool change script. That will make sure that the commands are executed before EVERY tool change, so just tell it to go print a square somewhere and it will prime the nozzle.

[beerdart]

Cura has a nice built in prime and wipe tower feature.

[Ola]

You could do this by adding 4 lines to your tool change script. That will make sure that the commands are executed before EVERY tool change, so just tell it to go print a square somewhere and it will prime the nozzle.

Wow!
Please enlighten me, I do not have any experience with writing G-code.
I assume I go to "Tool change G-code" and insert... what?
If you give me an example, I will figure it out hopefully.
I have a Replicator 2x, with two extruders.

[BaronWilliams]

You could do this by adding 4 lines to your tool change script. That will make sure that the commands are executed before EVERY tool change, so just tell it to go print a square somewhere and it will prime the nozzle.

Wow!
Please enlighten me, I do not have any experience with writing G-code.
I assume I go to "Tool change G-code" and insert... what?
If you give me an example, I will figure it out hopefully.
I have a Replicator 2x, with two extruders.

I did this with a purge line before.

Here's code for 1 extruder that should work on the Makerbot Replicator 2X.

Code: Select all

G1 X10 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 draw a line

Here's code for the other extruder.

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 draw a line

Put this code in the tool change G-code for the appropriate processes. Take a look at the G-code preview in Simplify3D 2.2.2 and you'll see that Simplify 3D 2.2.2 doesn't do this quite the way you expect it to. There are gaps in each purge wall. Simplify3D has some strange behavior. I would expect tool changes to happen for each layer when doing dual extrusion, but they don't, they happen every other layer. NOT GOOD. This means that each process lays down 2 layers before going to the next one. This makes the heads need to be primed even more.

If you put identical code for the purge line in each process so they build in the same location, then the purge wall is built with 2 different alternating colors, and sometimes there's some really strange stuff Simplify3D does with this, like making 2 lines at the same Z level at the lowest Z level. Weird.

[BaronWilliams]

A word of caution with these tricks. DO NOT RELY ON THEM. They are not officially supported by Simplify3D. They are hacks.

I was doing tricks to get 2 colored skirts prior to Simplify3D 2.2.0, and made a ton of factory files that relied on the tricks, and now none of those factory files print properly because Simplify3D changed how skirts work.

The sacrificial towers trick is the least likely to be screwed up in future releases. I recommend using that.

The tool change script behavior in Simplify3D is very weird, and how it works will probably be changed in the future. I think most people expect a tool change once for each layer, not once every other layer. So I expect this will get changed to once every layer, which is better for dual head printing.

[dennisjm]

Agreed, I've tried every hack everyone has ever posted on this with S3D on these forums. They all have shortcomings and don't work that well. You can't reliably control order of objects, you can't quite get the layer gcode to operate when you want it to, temperature issues etc. It's just not there yet and if you need to do a serious print with 2 extruders I'd consider Makerware or Cura. Drives me crazy when I need a serious dual extruder print but I also have complex support requirements! I'm sure the totally awesome S3D devs will get it right in one of their next releases

[JoeJ]

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.