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3Apr/140 hotend v4 for Rapman hotend v4 adaptation for Rapman machines

The assembled Rapman filament drive with the v4 hotend during extruding:

Get it here.


As you may be aware, back in 2010, the v3 version of the hotend (the PEEK based, so not the v4 all metal one),
was compatible mechanically and electrically with Rapman machines:

Starting from v4, the thermistor was intially switched to 104-GT2, which discontinued mechanical compatibility with the Rapman:

I then migrated to a Honeywell thermistor, which enabled me to leave out the fire cement, shown here:

These changes to the v4 hotend made it technically superior to the old one, and also way faster to assemble. However, it was neither mechanically nor electrically compatible with Rapman machines.

Recently, I have been approached by two people to get manufactured a fully compatible hotend for the Rapman. Two people are almost a crowd! :)

So with that in mind, I think I came up with a pretty good solution:

In detail

The length of the original v4 hotend was short by design,
however to maintain mechanical compatibility with the Rapman,
it needed a longer (73mm tall) hotend.
Pictured here is the assembled unit complete with nozzle, barrel and heatsink:

The new heatsink consists of two parts:
- The heatsink itself, which is 15.5mm longer than the standard one
- a disk, which goes on top of it, what you can mount on the Rapman machine using two M5 bolts.


The lower part of the hotend needs no modification, except it is
reverted back to the firecement version for using the 204-GT thermistor.

Summarizing the modification is basically a reworked heatsink and mounting plate.

I do hope it will serve well all the rapman users, who are still out there.

For reference, see this v3 hotend assembly page.

Some exotic combination

I will keep around the older heater block design which suits the
204-GT2 thermistor (and 104-GT2) because it is necessary for the Rapman.

The new and old heater blocks are compatible mechanically, so you can use the normal hotend with the older heater block if you need it for some reason.

Likewise you can get the Rapman version with the new heaterblock, if you have an exotic machine where this hotend suits better mechanically.


To date, I have only delivered two kits. Of these, one has
been installed and tested with very positive feedback.

Here is a quote from Rob:

I would like to add that the Hotend Unit you supplied is performing like a champion and has surpassed all of my expectations on its performance and reliability to date.
— Rob

How to get it

You have four variations to choose from:
- Assembled with 0.35mm nozzle
- Assembled with 0.5mm nozzle
- Unassembled with 0.35mm nozzle
- Unassembled with 0.5mm nozzle


Recommended extruder setup


Grab the complete setup here.

Many people ask me what setup I am using with the v4 hotend,
or what setup I recommend for it.

I bit the bullet, and I wrote this detailed article.

I am always trying to push the envelop of 3D printing, therefore my machine
is evolving all the time, so you can expect more articles in the future:)

The extruder shown here will also be available as a kit through the website.

This recommendation is for 2012 december, although it could have been built since around 2012 march.

Partlist (with pictures) hotend v4.1.1:

Go grab one! or Grab the complete setup! hyena v1.1:

Go grab one! or Grab the complete setup!

M8 nut with M3 grubscrew:

Go grab one! or Grab the complete setup! spring kit:

Go grab one! or Grab the complete setup!

40mm fan:
Are you wondering why is a cap there?: Maglev carriage fan

Wade's accessible extruder body:

Carriage with 2 fan holders:

Satchet of nuts and bolts:

608 bearings and linear bearings (LM08UU):

Just to see it in perspective:)

Downloading the .stl file of the RP parts

All of the RP parts, are from thingiverse.
However I have modified almost all of them. I will publish one .stl file per
week on thingiverse, referring back to the original thing and its author.

Assembly of the carriage

Here is the carriage one more time:

The linear bearings goes in there:

The two fans on the sides, and it looks like this when mounted on a machine:
(Note: There is one bar clamp missing from the above picture)

The modell of this print is available on thingiverse, as thing:39923. It is basically a touchup of thing:15534, which is based on thing:9869.


This is the idler of the Wade extruder pusher:

It has an integrated guide, so you dont need the grooved 608 bearing,
to guide the filament, its mere cost saving.
You can still have the grooved 608 bearing, it does not make things worse, this idler just duplicates the grooved 608 bearing feature.

The modell of this print is available on thingiverse, as thing:39933. It is basically a touchup of thing:17030 and thing:6703.

I have RP parts available in three different colors: white, green and black.
Here is a comparison between green and white print:


Here is the gears I use:

You may be wondering why I am not using herringbone gears.
Herringbone gears run a little quiter, and have a tiny bit less backlash.
Also they can handle higher torque.

However it does not affect print quality.
The filament has a backlash due to its inertia, and we compensate
for backlash anyway. It has the same number of teeth, so no additional
resolution either (not that we need it).

But the main reason is that it is more troublesome to print out, for no real
advantage, so I kept the traditional spur gears. You can print a
herringbone if you wish as an upgrade.

Wade pusher (extruder upper body)

Here we go:

It is a modified Accessible Wade extruder, mainly the holes were adjusted.
It is more accurate and compatible with
v4 hotend.

Here is how the gears, idler and wade upper body will come together:

The complete setup

The complete extruder assembled with carriage. Everything mounted:

You can see the setup is standing on two M8 nuts, so the
hotend is lower by just enough distance then the two fans.
It is optimised for the minimum height, so you have the
maximum printing height possible*.

Here are some more pictures, it is kind of rotating:)


You could have build this extruder setup from about february of this year (2012).
If someone would have published this extruder setup back in time, it
would have saved me some unnecessary circles.
So I hope you (dear Reader) find this article equally useful,
what I would have found it, if it was existed back then.

Printing quality

If you want to check what is possible
with our v4
hotend in regard of printing quality, or you want a trouble free
extruder setup, then go get one!

As a remainder, here it is the wade pusher printed in white:
(the white is the easiest to photograph, every irregularities are shown)

Im fairly happy with the overall printing quality, you can see it as
our current state of the art at 0.3mm layer height.

No worries, even finer layer height is possible, so it is not the
limit of what v4 is capable of.


Grab the complete setup here.

I think Im able to print one full set per week, and for start I have
3 full sets. I know it is limited, but it is not intended for general
public, just for the quality enthusiastic and those who want
a working printer first and a DIY machine second.

I have some leftover pictures, which would be too bad to miss out:)

And even moar:

I change slightly the commenting policy. I will close the commenting after a week of the date of publishing to prevent spams leaking through.

But in all occasion, please prefer the mailing list.

After the above deadline, any further discussion can only happen on the mailing list, in this thread.


Maglev carriage fan

Why do you need a fan?

As many of you may know, I have been using a double carriage fan (modified thing:9869) for my printer.

If only the hotend needed the air movement,
a single carriage fan would suffice, yet I get better results with double carriage fan.

So first and foremost the print itself needs the fan.

Buying fans for the carriage

Choosing the right fan is not easy. The ideal fan must be able to be driven directly from a PWM output of the RAMPS.

Many fans are not capable of be driven from a PWM output,
so it's mostly a hit and miss when buying small fans.

Why is a MagLev fan cool?

Well, the magnetic levitation itself is cool:) Also it is more efficient per watt (has more air blow power) than a ball bearing or bushing fan.
In my case the ball bearing fan can blow a lit match from 14 cm away, while the MagLev fan can blow it out from 41 cm(!) away.
So roughly 3 times more blowing power.

What to do if the fan is not able to be driven from PWM output?

Modify it like this:

I discovered my Maglev fans are not able to be driven from PWM output, they only work
with M104 S255, and not any value from 0-254.
Issuing a command less than S255 makes a strange pitch noise instead of turning the fan.

So I started experimenting, and I figured that I only need to add a small capacitor (any electrolite type capacitor works) between 4.7 uF and 100 uF.
(YMMV and also warning: some type of fans does not rotate even with this modification)

Also watch out for the polarity, here there is a pic showing how I modified my two maglev fans:


I think the capacitor is small enough not to destroy the aesthetic looks of things:

An example of these small fans on the carriage:

(note the superbright yellowish green clamp in the background:)

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in this thread.

30Oct/12Off hotend v4.1.1.


For previous announcement please read here:

The v4.1.1 version

Im really proud to announce hotend v4.1.1:

In a nutshell:
- v4.1. - aluminium mounting plate (that also means integrated setscrew in the heatsink)
- v4.1.1 - firesleeve

Aluminium mounting plate (v4.1.)

I replaced the wood mounting plate with an aluminium one.

Just to recall here is how the v4.0.5 looked like:

Here is the v4.1:

I also added an M3 setscrew, to fix the heatsink to the mounting plate
(prevent rotating the whole hotend at high speed).

Also here is how the hotend looks after 6 months of printing:

So the firecement is quite good solution, once it is applied.

Firesleeve added (v4.1.1)

To prevent skin burn, protect heater block against fan blow, and last but not least looks awesome:

Machine compatibility

This hotend is designed for reprap machines (or compatible).
However I had success reports from customers using in 24VDC system, like R2C2 electronics (you need different resistor, so definietly say it before purchase).

I would be really interested how others have mounted or adapted this hotend for their machine,
like or

If you happen to have a machine like the above, and you want assistance,
just drop me an email through preorder(at-arcoldothu.

Go grab one:

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If you have any thoughts to share about this article, please discuss it on's mailing list,
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Arcol Hyena v1.1

Available at:

History (v1.0)

For previous v1.0 announcement, read here:
and here:

V1.1 update

This is a minor, but really handy upgrade to hyena.

At one end it has 6mm flats for wrenches. So no more pliers to holding while putting the big gear onto the shaft.

This is how it should be mounted (flat end is the opposite one from big gear):

Here is a closeup of the two flat sides:

Here is how you should put the big gear onto the hyena:

Also here it is mounted on the extruder pusher:

(Note the M8 nut with M3 grubscrew! It is *really* useful)

M8 nut with M3 grubscrew:

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17Oct/12Off spring kit

Available at:

This is a simple spring kit for the extruder pusher:

Many people have trouble finding the right spring for the job, so
I decided I will offer the exact same springs, that I use on my own machine.
I settled to this spring after trying out more then 20 different springs.

The ideal spring is small, stiff, but not too hard to compress,
so the hobbed bar (hyena) does not bite into the filament instantly.

Also when you change the filament, the bolt is long enough so you do
not need to take it out completely from the extruder pusher.

Curious enough, how it looks mounted?:), here we go:

Go grab one!:

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If you have any thoughts to share about this article, please discuss it on's mailing list,
in this thread.