In the short video you can see our school’s Taz 6 messing up the start of its print. Something like this happens every time.
Can anyone tell me why, just after the hot-end moves diagonally to the starting point of the print, the green gear whirls and the extruder backs the filament out some distance. When the print first begins, the extruder pushes filament forward but nothing comes out for a long time.
I checked out the Start Gcode as shown in Cura, but this filament backing movement takes place after the start code has been executed. I don’t know how to access that potion of the print instructions.
It looks like it eventually starts to print okay. The retraction probably mitigates ooze at the beginning of the print. The retraction and wipe process are part of the start script.
The viewing box probably won’t be large enough, hover your mouse over the edge of the box and drag outwards to make larger. Click inside the Start Gcode text box, select all and copy the contents and post here, or post in a text file and upload it.
Also, your nozzle looks pretty far from the bed that’s why it isn’t sticking. What’s your Z offset set to? You can get that from the LCD panel Configuration, Z offset. Or use the software console M851.
Thirdly, you should always print a skirt at the very least to prime the extruder. I set the skirt to the minimums, 1 line and 25mm. If your perimeter is larger than 25mm it will continue to print the skirt for one entire loop. 2 loops if you were to set it to 2 lines, etc…
I will post gcode start-code later when I am at the correct computer.
I know a little bit of python programming and as I looked over the Start GCode I saw quite a bit that was easy to understand, (But why is the start and end code viewing window so goofy?)
I am 90% sure that the quick filament retraction on the video takes place AFTER the Start GCode executes.
I played a little with z offset via LCD panel. Quickly realized I don’t know what is correct setting. Do changes made there in the LCD panel become permanent settings for the TAZ?
I usually (all of 2 weeks) print a skirt but I had so many failures it was driving me nuts.
The print in the video is a 1 layer test square to help me diagnose without wasting a ton of filament.
I will post the GCode later this morning but I do not think the problem is there.
On the Taz LCD screen, I find Z Offset. and i can “tune” it.
Will the value I change it to be saved automatically into memory or must I adjust it each time?
Sorry Joe, but I believe you had a temporary brain fart . G1 Z2 E5 F75 says at the current X and Y, move the nozzle height to 2 and extrude filament until the current E position is 5. Previously the extruder was set to absolute mode, the current filament position set to 0, and then a couple of commands later, the filament was retracted by 30. Therefore, the result of the E5 should be to extrude 5mm of filament.
Yes, thanks for catching that.
If I am understanding the gcode, the extruder is in Absolute mode, so that command to extrude E5 at the end of the start code meant the machine has to back the filament out to get back to E0.
I think I need to mess with z offset now.
I’ll post another video soon.
I communicated with students via email. Apparently they modified the gcode to prime the nozzle by extruding 5 mm of filament. Could have helped if we were in Relative mode.
Because the machine is in Absolute mode, it sets the filament back to E0 as part of the basic print instructions (i.e. after start gcode executes)
I’ll change z offset and make another video.
I messed around for over an hour not making much progress.
As soon as the print extrusion begins, the ABS curls back onto the nozzle as soon as it is squirted out. See videos. Start of print hand fed curl
I pushed filament through by hand at various nozzle temps: same result.
The nozzle is about 4 days old with perhaps 8 hours of heated time.
I did a cold pull. Maybe interior of nozzle is asymmetric/slightly clogged? See pics
The cleaning filament has a very wide temperature range. Use the temperature of the filament you are cleaning out (i.e. PLA 190-220, ABS 240-260, etc.). Extrude filament until there’s there’s no visible residue. Then cool things down and do the cold pull. If that comes out clean, you are done, if not, heat things up and go again.
I do cold pulls at 100-120. Experiment with the cold pull temperature until you get a good imprint of the inside of the nozzle. On my TAZ 6 Single Extruders, I can shine a light into the top of the tool head and see (with the help of a mirror) a nice round spot of light through the nozzle.
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