It really depends on how flexible and “spongy” you want the resulting print to be. Most of my customers ask for 5-10% infill. i have gone as high as 50% - at that point it gets pretty stiff already. i printed several 20x20 calibration cubes with different infills 0%, 10%, etc up to 100% so i could see what the resulting impact would be. you might want to do that too. You’d be surprised how infill affects the end result.
I get a flex filament from fry’s called GP3D 2 and I use my feed tube with it. It is not as sticky as Nijaflex apparently and I get good results with it. Personally I would not print anything without the feed tube. You will get inconsistent layers as the feeder pulls the filament. Placing it above the printer will help as Stephano said, though.
I agree with this - ninjaflex is quite sticky even with PTFE (teflon) tubes, over a length with a curve in it.
Hang the spool above, ideally dead centre of the machine, in line with the Z axis, and as high above the printer as you can, to minimise any effect of movement of the axes.
I agree with this - ninjaflex is quite sticky even with PTFE (teflon) tubes, over a length with a curve in it.
Hang the spool above, ideally dead centre of the machine, in line with the X axis, and as high above the printer as you can, to minimise any effect of movement of the axes.
I don’t have a MakerBot but I do print with Ninjaflex. A direct drive extruder is required for ninjaflex or any other flexible filament. hope this helps!