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Strange Printing Behaviors

Posted by lagz4309 
Strange Printing Behaviors
October 27, 2019 02:59PM
Hello RepRappers,

Winter 2018 I acquired my 3D printer, a Tevo Flash, due to it winning All3DP best printer winter 2018. While I did have to traverse the steep learning curve of 3d printing, my machine exhibits strange behaviors that the very limited amount of other people with this printer did not seem to run into. The first issue I noticed was that the Tevo Flash Marlin firmware cannot read any Z-axis motion commands from Cura. I got around this by using Slic3r, which I found to be not nearly as intuitive as Cura. Nonetheless, I pushed forward trying to get this 3D printer to work. I had some small successes but any large prints would stop partially in. The only thing I can think that would cause this would be corrupted Gcode files from not ejecting the SD card properly. No matter, I will just have to be more careful now. The main problem that I am trying to combat now is a strange drifting mid-print. Anytime the Tevo Flash is printing an object with more than a single layer height, it ends up moving away from the print while extruding filament, then returning to where it is supposed to be, but on the way back the filament is retracted. I initially experienced this after my switch to Slic3r after Cura no longer could execute z-axis motion commands (I surmise the Tevo Flash's firmware from Tevo uses an older version of marlin that cannot read Z axis Gcode commands from the newer verisons of cura, I have made a custom flavor of marlin, using the latest version, for the Tevo Flash but right now I can't get accurate extrusion rates or temperatures but that is aside the point). Anyone have any suggestions? I've been trying to get this printer to work well for the last year and I am almost at the point of buying the new Prusa Mini for the same price this Tevo Flash was, just because I need to start printing soon

Thanks for any help.
Re: Strange Printing Behaviors
December 03, 2019 04:45PM
There is an issue with some Flashes having a bad cable to the sd card. Try printing through the USB by hooking your computer to your printer and see if that works. If it does, then you have a bad cable.
Re: Strange Printing Behaviors
December 04, 2019 12:45PM
I don't know what Slic3r version you have, but older versions did have a problem where they truncated the G-code output if you exited too soon.

You can look at the G-code with any text editor... it should end with a bunch of comment lines beginning with semicolons.

I don't think there's anything special about Z-axis commands Slic3r vs Cura, so I suspect the Cura problem is something to do with a bad Cura configuration.
Re: Strange Printing Behaviors
December 04, 2019 05:35PM
It isn't the slicer. My guess is that it is mechanical/electrical settings on the controller board. I think that you can tweak slicer settings to get things going though.

Try this:
Find your print speeds and extruder speeds and slow them down. You may be having issues with the current settings being so low that fast movement cannot be sustained.
The Z-axis tends to need more power to operate, which may be why that one is showing the most issues. Your description of what is happening with your filament is a classic case of the retract speed being too high (retract pulls go full distance, but the retract-return does not go all the way back). So, lets try some experiments. This is a set of speeds that should allow a weakly powered system to print:
Set print speeds down to 30-40mm/s
Set travel speeds to 40mm/s
If you can set Z-axis speeds independently, set that to 16mm/s
Set your retract speed to 30mm/s

Connect either by USB or by moving your SD-card back and forth. Use the latest CURA, it is pretty easy to configure, you may need to fiddle with the settings visibility to see all of the values that I mention above. If the settings above work, you can tweak ONE SPEED AT A TIME upward to find your limits.

DLC


Kits: He3D K200 Kossel, Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head
Scratch: Large bed Cartesian, Linear slide Delta, Maker-Beam XL Micro Delta
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