Tim wrote:A few comments. . .
(2) I notice that you have the standard "slow wipe" movement. Jin (on another thread) mentioned moving the Y position during the slow wipe. Otherwise, the right extruder wipes right over top of where the left extruder wiped, and ends up collecting on the nozzle whatever the left extruder left behind.
Not if you wipe them both at once....try it.
The right extruder, which is purged first, has time to cool while the left is purging. The thread usually falls off before it hits the bed, and by the time the right nozzle reaches the bed, the movement of the print head after the left nozzle wipe takes the right nozzle off at an angle towards the center, so it doesn't follow the path of the left nozzle wipe.
It might be an issue if the purge from the left nozzle globs up and collects as a wad on the side of the bed, but i always hang around and de-glob when i start a print anyway. (Got to keep an eye on the first couple of layers.) So I just knock it off if it does. Usually it just drops down. (I'll see what happens if i leave it alone next time it globs.)
It works fine for PLA, (so far), but I can definitely see that it might not necessarily be the best for other stickier/hotter filaments. The main thing i wanted to do was put the print head off the platform before homing the Z. First time i tried it, I whacked the right nozzle against one of the bed clips when it pulled forward to dodge them.
Had to rethink that one.
(3) I don't see any workaround for S3D's handling of the tool changing. I could have missed something, but as far as I could tell, S3D just forgets to retract the filament in the initial unused extruder, and it takes quite a while for the print to recover from that mistake (I have insisted that T0 is the left extruder and T1 is the right extruder, which caused me to have to swap the two in a number of places in S3D; it's possible that if I used the S3D default, which is to define T0 as the right extruder and T1 as the left, there might be fewer problems overall. But it looked to me like that way is defining the right extruder as the "primary" one, which I don't like, largely because the right side loses 20cm of bed space on the X axis). If the tool change settings are set in the "advanced" tab of S3D, then it's impossible to get the first retraction to happen, and all the tool changes after that are wrong, and there's nowhere to insert some scripted gcode to make it right. In the end, I had to set all the tool change distances in the advanced tab to zero to stop that, and put in the following tool change gcode script:
Code: Select all
T[old_tool]
G90 E0
G1 F1200 E-10
G92 E0
T[new_tool]
G92 E0
G1 F1200 E10
G92 E0
This is accompanied by making sure that the process is set up to have the left extruder (T0) put down the skirt, because that forces S3D to make the left extruder the first one to be active and print. Otherwise the start script, which retracts T1, wouldn't be right.
Yeah, I set mine up with left T0 and right T1 too, and had the same issue with the beginning of extrusion with the right extruder being extremely skimpy until it gets re-primed. (Generally just on that first layer.) I'm using the S3D fill-in-the-blanks spots right now, but I cut the retraction settings down by a lot. 5mm tool change retraction and -0.3mm extra recovery - the first few prints were getting globs at the start from using the same amount of re-priming filament as retraction. Since its PLA, the oozing isn't that bad, and i can get by with a lower retraction.
What i did discover, is that if you don't want to mess with making sure that you have enough filament to get things started on a two color print, and you haven't worked out a handy tool change script yet, print with
both a Shield and a Brim. The Brim attaches itself to the Shield, not the print, and in addition to keeping the shield upright and attached, it gives some priming time for the nozzles that it really needs to get things going smoothly.
Soon as the current print is done, I'll take a poke at one using your script.....(currently about 4 hours into a 7 hour print.) So far so good, but there are a couple of issues, and other oddities that I want to discuss with you guys when this gets done. I'm sure you've seen them.
This is my start script, most of which can be ignored because it does the same as yours, except for the bit at the end which retracts T1. Note that my slow wipe is also "wrong" and should make a jog in Y as Jin suggests. I haven't put that in yet.
Code: Select all
T0 ; start with left extruder
G28
G1 X0 Y50 Z0.3 F9600
G1 X208 Z10 ; move off the bed
G1 Z0.4
G92 E0
G1 E20 F225 ; purge left
G92 E0
T1 ; switch to right extruder
G1 E20 F225 ; purge right
G92 E0
G1 X160 Z0.1 E1.0 F1200 ; slow wipe
G1 X140 Z0.25
G90 E0
G1 F1200 E-10 ; retract inactive T1
G90 E0
Depending on what you are printing, you might be able to take that last retraction out of there. It really doesn't have much of a chance to dribble at the very beginning, and if it does, it's likely to be on the bed during the wipe. Maybe just for the first layer we could drop the temp on the inactive nozzle to keep it from drooling, instead of retracting? Then it would at least be primed and there wouldn't be a gaping hole in the print at one edge. (Yeah, I've seen it all right!
) Would take longer to print the first layer, but it might not be so bad overall.
I just updated Simplify3D to 3.0.2 today, and found no difference in the gcode it produced, as far as the tool changes were concerned.
Excellent - I can try the script for tool change without modification. I do want to see how the S3D settings produce one first though for comparison. (Probably should have picked an easier one to start with - saw this "Julia Vase" thing in one of the vids and just grabbed a copy for testing. Taking forever!
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