Wiper

[jsc]

Here's my first attempt at a tool change wiper. It's just a bar that hangs off the right side, covered in some kapton tape to make it easier to clean off. The tool change script retracts the old tool 6mm, switches to the new head, moves it just past the wiper, extrudes 6mm to get back to zero, and moves over the wiper at a moderate speed to wipe off any residue. It is adjusted to barely contact the nozzles as the pass over. Here is my tool change code:

Code: Select all

; tool change: [old_tool] -> [new_tool]
T[old_tool]
G92 E0
G1 E-6 F2400
G92 E0
T[new_tool]
G1 X225 F12000
G92 E0
G1 F2400 E6
G92 E0
G1 X215 F1200

My startup code also uses the bar to prime and wipe both nozzles. It does T1 first and leaves it in a retracted state, then does T0 and starts immediately:

Code: Select all

M201 X1000 Y1000
G28
T1
G1 Z5
G1 X225 F9600
G92 E0
G1 E25 F225
G92 E0
G1 E-6 F2400
G92 E0
G1 X215 F1200
T0
G1 X225 F9600
G92 E0
G1 E25 F225
G92 E0
G1 X215 F1200

Simplify3D does some really strange things with the tool change code, like changing from T0 to T0, then from T0 to T1, then T0 to T1 again. It seems broken. I had to go in and fix up the gcode in an editor. The comment at the top of the tool change script makes that easier, as you can just search for "->". You need to remove any instances of weird tool changes manually. Thankfully, they appear to all happen only near startup. Make sure you keep looking until it seems that all the tool changes are swapping back and forth between T0 and T1 regularly.

The wiper seems to reduce contamination somewhat, but part of that is just moving the nozzle away from the print while resetting. If you don't do that, it will reset the new tool head wherever it happens to be, then drag the ooze over your print getting to the next print position.

There is still contamination happening from the unused head drooling slightly while not printing. Maybe some more aggressive retraction will help with that.

[Rocketdog]

Thanks much for the code. Can you post the STL file for the bar?

[jsc]

Here's my wiper model. After some more playing around with it, I'm not sure it's going to work out, though. I mean, it's better than nothing, but what happens is that the wipes build up after a while and then one of the nozzles will pick up the patch and bring it over to the print. You have to be cleaning it up constantly. I'm going to try Cura next, which I've read has "wipe tower" support (it will automatically build a tower to wipe the nozzles on).

What you want is some sort of brush, which will clean and retain the ooze.

Also, as I mentioned, the next problem is that even an aggressively deprimed nozzle will ooze a small amount if left unused too long, and that tiny filament blob will end up somewhere on your model. Hopefully in the interior, but if the print is small, probably on the outside. I tried cooling down the unused extruder to 190 as suggested in the wiki, which does improve matters, but that blows up the printing time with all the waiting to bring up the new tool up to temperature.

Still, please play with it and see if you see any improvements to the procedure! Oh, use M4 sized hardware; #6 is the closest SAE equivalent.

[jsc]

Cura can generate both a "wipe tower", which serves to prime the incoming tool head, and an "ooze wall", which is a shell around the whole object that catches drips from the oozing unused nozzle before they contaminate the exterior. The dual extrusion handling over all seems much better than Simplify3D. Once I've managed a decent print, I will provide my configuration.

[jsc]

Cura's dual extruder support is good, better than Simplify3D. I ran the Julia vase at half scale as a test. The wipe tower got knocked over about 3/4 of the way through, causing a spaghetti mess, but the ooze shield kept it away from the model.

Getting the ooze shield off was a bit tricky. Kind of like trying to get the meat out of a crab, if the crab had holes that the shell was threaded through. Here's a photo a little way into starting the removal:

julia vase.jpg (69.66 KiB) Viewed 15581 times

And here it is after complete deshielding:

julia vase 2.jpg (71.96 KiB) Viewed 15581 times

[Levi8than]

That's pretty cool.

[Dale Reed]

Josh was printing that vase today when I stopped in to pick up my dual kit. He was using two colors of PLA, and I don't recall seeing a wipe tower, and there was definitely no ooze shield. He's got some great retraction settings and tool change G-code figured out -- I hope he plans on sharing (if he hasn't already)!

I need to get some pigmented PET+ to try with my clear. If jimc or I can get that stuff to print without a wipe tower and without an ooze shield, we really will have achieved "nerdvana"!!!

Now, I'd best finish reading the board and go install my dual kit and try some PLA.
Dale

[Levi8than]

I'm still thinking on pneumatic/solenoid silicone plug to close the hole is the way to go.
But it would need to rotate into position or even slightly lift the hot end out of the way to not hit the second color's print.
It's all there in my head, but unfortunately I'm not a mechanical engineer, nor do I have as much time as I'd like to tinker.

[Dave K]

Josh was printing that vase today when I stopped in to pick up my dual kit. He was using two colors of PLA, and I don't recall seeing a wipe tower, and there was definitely no ooze shield. He's got some great retraction settings and tool change G-code figured out -- I hope he plans on sharing (if he hasn't already)!

I need to get some pigmented PET+ to try with my clear. If jimc or I can get that stuff to print without a wipe tower and without an ooze shield, we really will have achieved "nerdvana"!!!

Now, I'd best finish reading the board and go install my dual kit and try some PLA.
Dale

I'm really interested in PET+ settings as well. Right now, the only filaments I have other than black are PET+ filaments so that's what I used. I did a first print for adjusting the nozzle 1 offset, and it became clear that PET+ is going to be a challenge because of it's tendency to ooze, even with a healthy retraction setting. I'm not sure how much time I'll be able to put in this weekend on printing, but I hope to do a few more PET+ prints with different settings.

The only hiccups build-wise were a swapped fan0/fan1 label and having to put the extruder 1 motor connector into the Rambo board reversed (seemed to me). Both minor.

[Dale Reed]

The only hiccups build-wise were a swapped fan0/fan1 label and having to put the extruder 1 motor connector into the Rambo board reversed (seemed to me). Both minor.

Dave,

IIRC, when I built my M2 kit, I tested the steppers at first powerup and they all ran backwards. I had to plug ALL the stepper motor connectors into the RAMBo "backwards" -- by that, I mean with the wire colors reversed from the order they were shown on the provided diagram of the RAMBo board. So maybe they "fixed" the wiring for this new harness so the colors match the diagram, but it looks wrong when you plug it in because it's different from all the others!

Just guessin'... But thanks for the heads-up!
Dale