My custom direct extruder

I´ve seen some great bowden extruders which even worked with very good retraction settings, the one on the Eventorbot is not one of them.
The first problem I had with it was that the geared motor did only the backward part of the retraction but failed to push the filament forward again.
A new NEMA 17 motor solved that problem and even when directly driven without any gear reduction seems to work fine. I still am not convinced about the use of the huge gear reductions the Wade extrudes bring with them but that a topic for another conversation.

The clothpin held down the motor

I decided rather quickly to go for a direct driven non-bowden design and started with a faceplate which would serve a connector for motor and filament guide. In the first version my goal was just to mount everything but didn´t pay much attention to the forces that are at play here. The way the motor was connected to the housing would push the motor up rather then push filament down into the nozzle.

In the 2nd version I went for a spring loaded filament guide which directs all force down where it belongs. One issue still even in the rather balaced design is that the clamping pressure is between the housing/filament guide and the motor screws. If that is not well fitted the plastic will give in and filament will just slip.



For the 3rd version I had the idea of putting a cogwheel on the motor shaft and adding a 2nd axis with a 2nd drive gear to hopefully give the filament grip from both sides. The would apply clamping pressure only there where it is directly needed.

Wing nuts, simple, cheap and useful

Here is something I like for multiple reasons. Thingiverse user Mooncactus provides us with a customizable option to make wings for normal hex nuts. In my local DIY store they cost ~4€/6pcs, making them my self is much more fun.

Fine thread Z axis - succes

I am carefully optimistic to have managed one of the main Z axis problems.

With the original 5/16" threaded rod I had one deteriorated layer for every rotation the rod did. Which resulted in a gap every 1.4mm. I still dont exactly how this happened but there must have been something in the thread which would cast the extruder to not lay down material well.

Before with 5/16" threaded rod

Here you can see how I not only get a gap and an upwards curled filament line but it also looks like the extruder stuttered.

After with M8 fine thread

Now this looks much better. Since the filament is half transparent they layers are much more visible and the main bed wobble is still visible but the whole wall look much more uninterrupted.
With better quality filament (I really don´t recommend buying "Jet PLA") and a solid color I might be able to actually print decent quality.


Coming up: Speed testing. I want to reach an accelerated 80 mm/s and the print parts to change the whole Z axis assemble, but the fine thread will definitely be a part of it.

Final judgment for filament producers

Comparing all machines brought some interesting insight, but judge for yourself.

Here is a judged comparison (for raw data see below).

	Filabot	Filastruder	Extrusionbot	Filafab
Price in €	475	205	460	850
Crusher	In planning	No	No	Yes
ABS	Yes	Yes	Yes	Yes
PLA	Yes	limited	Yes	Yes
Speed cm/min	12-50/1kg in 6.6h	15-60/1kg in 12h	60-91	120
Spooling	No	Yes +120€	Yes	No
Kit/Assembled	Kit	Kit	Assembled	Assembled
Max 21	13	13	17	17

Red = 1 points; Yellow = 2 points; Green 3= points

Filabot:  Relatively high priced for its capabilities. For the same price the Extrusionbot looks much better.

Filastruder: The big plus here is the price however the specs show that this machine only covers the very basics and the PLA issue troubles me.

Extrusionbot: Has the best cost benefit ratio, combines a medium price with high extrusion speed and crusher and spooling are built in.

Filafab: Leads with some impressive speed, but is also double as expensive as all other models.

These are the raw data.

	Filabot	Filastruder	Extrusionbot	Filafab
Price in €	475	205	460	850
Crusher	In planning	No	No	Yes
ABS	Yes	Yes	Yes	Yes
PLA	Yes	limited	Yes	Yes
Speed cm/min	12-50/1kg in 6.6h	15-60/1kg in 12h	60-91/n.a.	120/n.a.
Spooling	No	Yes +120€	Yes	No
Kit/Assembled	Kit	Kit	Assembled	Assembled

Fine thread Z-axis

I noticed some gaps between layers in all my prints which reoccurred every 1.5mm I quickly assumed that this had something to do with the lead screw/ z-axis because 1.41mm is the pitch of the 5/16" threaded rod.
(See here for details)

I went out and tried to find threaded rod with a pitch of 1mm not only because M8 fits better in our coupler but also because there is much less play between nut and rod. That turned out to be surprisingly hard because even though fine thread rod was easy to find, the nuts weren´t. Everything except a standard nut is somehow not produced.

With half hex rivet nuts and flanged hex nuts out of the game I ordered normal M8 nuts and planned on upgraded my z axis with kkronyaks Floating Motor Z-Axis. As a first step I wanted only to change the part which connects to the bed carriage, ripped my machine apart and noticed that the rod mount does´t have the same width as the original metal mounts.

But then I had a stroke (of genius). Since I have now 100 M8 fine thread nuts I have some space for trial and error experimentation. So I dremeld me some nuts to fit in the holes of the original mount.

At least I managed now to get the fine thread into my machine and when I put it back together I print all parts of the Floating Mount, because the 4 screws in the diamond shape promise much more stability for the bed as the original pattern with only 2. 

Filament producer options - Extrusionbot

The Extrusionbot

A mid priced machine (625$) from a successful kickstarter campaign looks like it was designed for desktop use with a small foot print and a convenient auto spooling feature, claims to be very fast and doesn't seem to discriminate against PLA.

This seems to be it for available filament producers. There some building templates and how to´s for DIY machines and 2-3 more in the development phase I didn´t consider so far.

Next time: A comparison of all machines

Filament producer options - Filafab

The Filafab 

A successful kickstarter project as well, priced at the high end at 699 pounds, which is double the price the kickstarter models sold. The machine looks sleek and well designed, claims to be suited for ABS and PLA and has a build in crusher, which could account for some parts of the raised price.

Next time: Extrusionbot