hotend v4 for Rapman (Noone left behind)


This blogpost has been published on . 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

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