Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Filament guide for MK8 spring loaded aluminium arms for CTC Replicator Flashforge Dual (update: for flex)

by coreZair Apr 27, 2016
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As I was printing your files I noticed you can use 2 old nozzles [drilled out] in place of the printed parts.

Thank you, your design helped me a lot, I use it on a CTC I3 Pro B with the aluminum feeder in bowden configuration. The only problem has nothing to do with your filament guide but the hydraulic fittings I use for the 4mm o.d. teflon tubes. When inserting the filament it stucks in those fittings so i have to drill the holes to 4mm but that is not easy done because of the m6 Tthread. How did you manage it? or where did you get your fittings? On the photo they look equal to mine

I know, I got the same problems with those tube couplers. I'm used to unplug the bowden tube from the coupler every time I change the filament and fiddle it in manually. It is not perfect to do so, but only takes a few seconds longer.
Some years ago I printed some little tubes which sit in the thread, between aluminium arm and coupler. They guide the filament better trough those annoying hole diameters, but not perfect. Because of your comment I think about designing a better version for that. When I am successfull I will add it to this thing. :)
Thanks for your inspiration. Kind regards.

Work in Original Extrusor??? TKs

For which printer model?

Sorry i am not familiar with this printer model. But just give it a try and let me know. It's a simple mod. :)

Where did you get the Y carriage?

Does it fit to the Tevo Tarantula's extruder?

Tried. It does Not.

THANK YOU SO MUCH FOR THIS!!! I have had a roll of Ninjaflex that I had tried unsuccessfully to print on 3 different printers. I used your top and bottom filament guide and I am finally able to print at 45mm/s. I suspect that it will go faster if I tweak it further.

Hi butterball_z, you are welcome! I am glad it works for you nicely :)
What kind of printer you got? I would like to know on which printers it works best and worst. Some printers got different spacing and part dimensions, which could be a problem.

Kind regards

This should help with flexible filament, too.

love you so much, my printer has been having a problem with not loading filament.

You are welcome mate!

ABS works flawlessly with your flex version! Very nice

working on a new version specialized on flex filaments atm

Works flawless with flexible TPU for me. The print speed should not exceed 30mm/s in normal cases. I tested TPU up to 40mm/s and it finished the print nicely at 210°C hotend temperature. It is not recommended to print flexible filament faster than 30mm/s in general. At least it's a golden rule for TPU, maybe there are some other flex filaments which can be printed faster :) Please check your settings.

In my experience the most common point of failure for flexible filaments is the nozzle cleaning script at the beginning for all the makerbot-like printers (the straight line which is printed at the beginning on the edge of the heatbed after heating up). This line is printed at a much higher flow rate than during print with 0.3 layerheight and 30mm/s, which leads to bend and twist of the flex filament before it can enter the hotend. The bottom part STL of this thing is not tight enough for no bending of the filament at all, but tight enough to handle much higher flow rates than without. I am using the lower version of the bottom part, which forces me to set the hotend a bit lower, but allows me to use the tighter version of the bottom part, which should be better for flexible filaments as the higher version.
If you have the option you should change the starting script to a slower cleaning speed. I think the command "M203 E1" in the starting script should do the trick.

In Simplify3D you can change the line in replicator starting script
from "G1 X-90 Y-73 E24 F2000"
to "G1 X-90 Y-73 E12 F2000 ; line across the edge of the bed E12 for FLEX instead of E24"
This modification will do the trick and the flex filament will not bend/clog during start of the print job.


You can actually use the hole assembly arm and back plate in the ctc printer. you have to cut the bottom part of the back plate off. make it the same size as the old part. then use the heat sink that came with it and bolt it on.