I know you can switch colors mid-print by adding G-Code to automate the stopping, retracting, etc. which I’m not ready to attempt yet. However for us non-Gcoders there at the top of Repetier-Host is a Pause button I haven’t touched, because I didn’t need it*. It turns out it is easy to pause, swap out filament colors and continue. Experienced users probably already know how to do this, so this is sharing from one noob to another.
This procedure works as written if you have set up your slicer to do perimeter first, then infill.
Have all of your colors of filament mounted, ready to go. Have a piece of paper ready to stick under the extruder when you stop it.
Click the Pause Print button when the print is just starting to do infill on the layer previous to the want you want it to change on.
As soon as the printer stops, use the manual Z axis button and raise it 10 to 20mm. Stick a piece of paper in under the extruder as fast as possible so ooze doesn’t collect on the printed object. And/or, retract some filament right away.
Use the extruder retract button to extract the filament, or pull it out by hand after releasing drive tension, your choice.
Use the right most extruder feed (the fast feed) in 10mm and 1mm increments until you get the filament in to the hot zone. Don’t over do it, you’ll have to learn how much fast feed you can get away with. Switch to slow feed, and feed until you’ve purged the previous color. this will collect on your piece of paper.
Take away the waste filament, take out your piece of paper, Click Continue Printing, and you’re done!
Repetier-Host will keep the heaters and fans on during the pause, and remembers where the Z axis was. So as long as you don’t bump anything or move anything by hand, your print should continue right where it left off.
I’m doing this with the new K8203 extruder. I am guessing it might work just as well with a stock setup or any of the other hot ends.
I may not have paused, but I sure have used “Kill Print” a lot as I’ve learned, tweaked and adjusted!
I’ve made several 100 2 and 3 colour prints on K8200 using only manual removal and feed of filament - turning the gear wheel by hand. I was wondering if it would still be possible after upgrade to K8203.
Have you done it? Is it possible to pull the filament out quickly and manually on K8203? (I find winding out on K8200 is not reliable - gets stuck)
I put in @pause at the appropriate point in the gcode. I case you don’t know. 3D view and G Code editor. Click on ‘Show single layer’ radio button. Click on box to right of ‘First layer’ and use arrow keys to cycle through layers. Go to one before you want to change. Click ‘First layer’. Increase by 1 and ‘First layer’ again. The point to add @pause should be at the bottom of the code window.
I add code to the ‘Run on pause’ file in the gcode editor.
M102 ;Extruder reverse
G91 ;Relative
G1 Z2 ; Z 2mm
G90 ; Absolute
G1 X190
M107 ;Fan off Start fan in code M106 if needed
M101 ;Extruder forward
This lifts the Zaxis by 2mm and moves the extruder to the side. I then raise by 10mm to get my paper under and clean nozzle with brush if necessary after new colour is through.
Thank you for sharing the detailed steps, when I get time I will try your instructions, . I am not a G-Code manipulator yet, I feel good about being able to modify configuration.h and reflashing so I am making baby steps. I used to do simple things in DOS many years ago and have dropped in to a terminal window in linux, so command line stuff isn’t exactly scary.
As far as the K8203, I retract and remove filament with Repetier-Host “-100” button all the time. I do it when I am changing colors, and when I am done printing before the hot end cools. I think only once in the dozens of times I’ve done this I have had a problem, and that is when I let the filament stay loaded overnight. I warmed up the hot end, and went to retract and the filament broke inside the heat separator area and left a piece behind. Fortunately I was able to forward feed filament through and didn’t have to disassemble the extruder assembly at all. The K8203 feeds and retracts nicely with Repetier Host manual commands, so I imagine coding feed movements might work well for someone.
On a side note, the K8203 Velleman firmware did not need feed calibration, it was correct “from the factory.” I am talking about manually feeding 100mm, get 100mm.
The K8203 does have a pressure release lever to remove tension from the hobbed gear, but I think I’ve only touched it a few times since the kit was installed.
