FlexionHT Extruder for the Wanhao i3

Over New Year’s I ordered the Flexion-HT extruder for my Cocoon (Wanhao) i3.

I really had a hard time using the various extruder mods you can find about the place attempting to print TPU.

I purchased mine paying the full RRP in Australia (ouch) from 3D Printer Gear in South Australia (the Aussie dealer). Flexion box had previously been unsealed before it arrived.

The Flexion is expensive but it has worked first time with no major operational headaches.

The online instructions don’t reflect the HT version very well (nearly no at all). For others following the online instructions here:

Single extruder


Here are my additional notes (read in addition to the Flexion site notes as of Jan 2017):

Flexion will be updating instructions shortly (Feb 2017) – so some of the following may appear superfluous!!!

For Step 2: Disassemble hotend

– The heater element wiring is stiff but brittle. Be careful with it and the thermistor.

– My heater grub screw had seized, I had to remove the block and use a tiny drop of WD40 on the screw for an hour to un-seize it.

– The supplied hex key/wrenches supplied with the Wanhao are very weak. My smallest one bent. Careful using ball ended wrenches, they can round the edges of the hex screw if not seated properly or if they are just a fraction the wrong size.

I intend to finally have both hot ends easily swappable with a dedicated thermistor and heater cartridge for each.

Step 3: Assemble hotend

– My kit was missing the M4 screws for the thermistor clamp, the originals are M3 and don’t fit. Found out later there is an M3 thread hidden under the silicone cover.

– Also missing were the two washers for the stepper motor (not needed for me – see Step 5)

Step 4: Install heater

– My heater cartridges (both original and ebay Chinese spares) were loose in the block. The original heater was also loose in the original block.

BIG TIP FOR AUSSIES: the recommended procedure is to use alfoil (al-u-min-ium foil) to wrap the element to make it fit snugly. The ‘freshness’ foil (the one you tear out to access the contents) from the top of a Milo tin fits perfectly and makes a great shim.

I have much better temperature control, ie not jumping around as much, with the element snug in the block! This would apply for original blocks as well as my heater was not snug in it either.

– The new mounting block has a built in heatsink. (This is now going to be standard for both the HT and non-HT kits according to new notes on the Flexion website). I DID need two washers under the original nylon spacers to be able to screw the fan down tight.

Step 4b: Install insulation

Not needed, both hot ends came pre-assembled both with insulation. I assume the spacing for the nozzle and barrel are correctly set by Flexion (yes that is correct – pre-set at the factory)

Step 5: Prepare motor

I did not need the extra washers.

Step 7: Install assembly to X-carriage

– Yes, no need for the old heatsink.

Cooling fan looks a bit ungainly with only two screws and at the end of the spacers but the fan is light and it seems to work well. In fact, I wouldn’t be surprised if the block could work without the fan blowing on it, using natural convection!


and finally,

Hard to tell which is the HT and which is the ‘normal’ hot end supplied in the kit, the HT is the one with the smooth barrel that clamps to the block. The normal one has an indented surface. Flexion say they will be colour coding the silicone, great idea! (Mine now has a Sharpie ‘H’ on the HT hot end for when I need it)

I have not used the HT option yet. No idea how that performs.

The silicone jacket seems to insulate the heater block much better than the original Kapton tape/cotton.

E-Steps should not change (Flexion recommend 95-96 steps/mm)

The nozzles supplied are not plated, just plain brass, I think MicroSwiss may be bringing out some plated nozzles to suit soon.

I have run PLA and TPU through and it has worked a treat.

I have two rolls of Flexible filaments. One is a roll of the Jaycar stuff and really doesn’t like sticking to my glass, but when it does, it produced good prints. The other roll is Filaform Grey – 90A and it works just like PLA when printing.

++ Like ++  Easy loading and swapping of filament, just reverse the old filament out, advance the new filament in!

Also swapping filament on the fly… I just snipped the filament and fed in the new filament as the print was in progress.

Expensive? Yes. But it works as advertised. Pretty much plug and play with flexible filament and all the other benefits over the standard extruder setup.

I am happy with my purchase after many frustrating hours trying with other solutions, the Flexion works and works well.

Photos follow – anything different in comparison to your printer is probably a mod I have done.


My “licorice allsort” created by changing filament on the fly.


The Flexion installed


The Teflon feed tube. The red wires are from my replacement heater cartridge after the grub screw in the original heater block had seized and the old one couldn’t be removed (WD40 has since fixed that)


Noctua 40mm fan mounting.


1 thought on “FlexionHT Extruder for the Wanhao i3

  1. Hey, Its been a long time since this post, Hopefully you are still active!

    I have read the Flexion guide, and your own, and seem to be haveing a huge amount of issues getting it to extrude reliably even on the first layer.

    I’m just wondering what the results are from a M503 command if thats possible? as I think my Feedrate settings are way off for the E!


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