Greetings! I've been running several Flashforge 3D printers for over a year now, and I'm starting to play with flexible filaments. In 2013 I had a lot of success using a Makerbot Replicator 1 with a modified extruder upgrade to print (slowly) a huge 4inch to 2 inch Vacuum Adapter for a friend out of Ninjaflex filament - it was a pain in the butt, although it did print successfully.

Now I am trying to print flexible objects using Sainsmart TPU filament and noticing a major issue - my perimeters are not bonding well enough! I've been playing with every various slic3r setting I know to adjust and tweak the settings. I'm getting very close - my prints are coming out very nice - except when I flex them - the sidewalls delaminate completely. When printing an object like a vase, I can literally pull apart these layers by hand. (The layers are well bonded, but it's the damn perimeters I can't get to bond).

Please note I am using this extruder upgrade - http://www.thingiverse.com/thing:989965 and found it works pretty good, as long as I don't mess with my print settings too much.

Here are some key settings on my Slic3r Configuration:
  • Diameter: 1.70mm
  • Extrusion Multiplier: 1.15 (trying to mess with this to increase wall thickness - doesn't seem to help much with flexible filaments)
  • Print temperature: 220C (was printing at 235C, testing lower temps to see if it affected print quality - doesn't seem to)
  • Bed Temperature: 45C (using PrintInZ Zebra Plate bed - no problems with bed adhesion - it's perfect!)
  • Extruder Retraction - 2mm
  • Retraction Speed - 15mm/s
  • Wipe on retract: Enabled
  • Perimeters: 3
  • 20% infill
  • Speed
    • Perimeters: 25mm/s
    • Small Perimeters: 20mm/s
    • Infill: 10mm/s
    • Solid Infill: 10mm/s
    • Travel: 65mm/s


As you can see - print speeds seem to be ok, temperatures are ok. In fact the printer seems to be doing ok, it can print objects beautifully. Except when they are a vase or other tall hallow object. The layers will all bond to the base, but the sidewalls immediately break apart when I "crush" the print.

I suspect my Filament diameter and Extrusion Multiplier could be the key to fixing my print issues, but every time I crank up the multiplier past 1.25, my printer jams around the 6th print layer (10+ minutes into the print).

Please help! I really need to reliably print flexible filaments consistently (I'd even consider purchasing an upgraded extruder design if that would fix my problem)