About ooze and duel extrusion

[dennisjm]

So... I've been printing some pretty complex parts. They have support material on the inside, outside, and ABS little parts all over...
anyway, things are going pretty well, but I'm curious about one thing.

Makerware has this option to print a purge wall on the side so that it can keep the ooze from collection on the model. Typically you see this when one extruder is idle for a while while the other is printing its stuff. Then when you switch you get a glob of material wherever you start.

Question is.. what do you do? Switch back to makerware? I've finally got things tuned pretty well in S3D it seems.

[jimc]

since i am not running a MB and never used MW i have never really seen these walls but i have heard about it quite a bit. is this something that you could keep a model of and just drop two on the table near your main part then just scale to about the same height? one for each extruder.

[dennisjm]

Well, You could potentially do that... but...
there isn't a way to ensure that the active nozzle prints the purgeWall before printing the important object. (Or is there?)

Each layer should cycle like this:

1) ABS purge wall
2) ABS
3) Support purge wall
4) support

It doesn't guarantee that you don't get ooze on your print but it can help.

[dennisjm]

I should mention... I don't know if Makerbot actually cycles each layer exactly like that or if it's more advanced. I haven't actually used it. I just saw the feature and have also seen the ooze getting on my prints and started to make some connections that they might have something important going on there.

[KeyboardWarrior]

So... I've been printing some pretty complex parts. They have support material on the inside, outside, and ABS little parts all over...
anyway, things are going pretty well, but I'm curious about one thing.

Makerware has this option to print a purge wall on the side so that it can keep the ooze from collection on the model. Typically you see this when one extruder is idle for a while while the other is printing its stuff. Then when you switch you get a glob of material wherever you start.

Question is.. what do you do? Switch back to makerware? I've finally got things tuned pretty well in S3D it seems.

Layer change purge; purges way too much for every layer change. Just a first test. Linked the video

Scripts-Layer change Gcode
G90;
G1 X-120 Y-70 Z30 F9000 ; move to wait position off table
G1 E25 F300 ; purge nozzle
G1 X-115 Y-65 Z0.15 F1200 ; slow wipe
G92 A0 B0;


http://vimeo.com/99854561

[dennisjm]

Holy shmoly that's a lot of purge between each layer!

Anyhow, that would _help_, but it really needs to do the purge between materials. Not sure if there is a way to do that or not.

The purgewall feature wouldn't even help all the way anyway, what I'm finding is that while I'm busy printing supports, the other extruder is oozing material on the print while it's idle anyway.

[KeyboardWarrior]

Holy shmoly that's a lot of purge between each layer!

Anyhow, that would _help_, but it really needs to do the purge between materials. Not sure if there is a way to do that or not.

The purgewall feature wouldn't even help all the way anyway, what I'm finding is that while I'm busy printing supports, the other extruder is oozing material on the print while it's idle anyway.

All i'd need to do is change the script to place it into the tool-head change G-code. Yea, that's a lot of extrude inbetween each layer, that's why I stopped the print right away.

[KeyboardWarrior]

Holy shmoly that's a lot of purge between each layer!

Anyhow, that would _help_, but it really needs to do the purge between materials. Not sure if there is a way to do that or not.

The purgewall feature wouldn't even help all the way anyway, what I'm finding is that while I'm busy printing supports, the other extruder is oozing material on the print while it's idle anyway.

All i'd need to do is change the script to place it into the tool-head change G-code. Yea, that's a lot of extrude inbetween each layer, that's why I stopped the print after that video (In addition to purging being kind of useless for a 1 material print).

[dennisjm]

<hand to the head /> doh!
I didn't even look at the process tab before I posted that last comment. I had forgot there was a toolhead change gcode. I'm going to check that out and see if I can make a purge wall simply by putting the right gcode in there.

[dennisjm]

So this is working sort of to use the tool change code. The problem is I want to extrude a short line for each tool. In the toolchange script is going to get executed twice for each layer. So it will be trying to extrude the line in the same spot for each tool. I tried putting the same code in layer change and tool change with code to change the tool but then I get a layer change -> tool change at the start of the layer and then another tool change in the middle... so the 2nd toolchange then tries to extrude in the same spot again.

I think ideally I just need code in the tool change but some way to differentiate which tool. The alternative is to do the wipe on the bed like your sample video but the problem there is as the build gets higher pretty soon that doesn't work.

Any suggestions on how to fix?