Chapter 7 – Hotend
Unlike most printers, the Tantillus is compatible with very few hotends. The Tantillus has no active cooling of the cold end. Therefore all full metal hootends can NOT be used without further modification of the printer.
We made this decision with full intention. The aim was to move as little mass as possible from the outset. Using a hot end with passive cooling was therefore the ideal way
Due to the very compact size and the extremely low weight we decided for a Hotend classic. The Merlin Hotend.
The Merlin Hotend was developed in 2011 by Björn Marl and is still praised by insiders today. After it was no longer available, it has now been reissued by RepRap enthusiasts around Hackerspace FFM and is now available again at Protoworx.de.
In the process of the development of the Tantillus Angelo came up with his remake of Merlin. The new version offers two different even smaller heating blocks with longer heating zone.
The Merlin Hotend uses airbrush nozzles. Airbrush nozzles are available in 0.2, 0.3 and 0.5mm. These are more sensitive than other nozzles, but allow very fine prints. This fits well with the high-resolution XY axis of the Tantillus.
Airbrush nozzles require a certain learning curve and absolutely exact calibration due to the nozzle geometry. Honestly, you can’t call it beginner hotend, but it has a huge potential. The nozzle geometry ensures very little heat radiation on the pressure part. The very slim shape also makes it possible to get a lot of cooling air to the nozzle or under the heating block.
Due to the teflon inliner and the passive cooling concept the Merlin should not be operated above 260°C.
Highly abrasive filaments or highly filled filaments should not be used. However, these are usually not compatible with the small nozzle sizes (0.2/0.3) anyway.
The Merlin is sufficiently cooled by the stationary part cooling of the Tantillus R.
It is therefore not necessarily recommended to print high temperature warping plastics.
These usually require a completely deactivated pressure part cooling and high pressure temperatures, so the hot end would also not be cooled.
All really common printing materials like PLA, PETG, TPU,… but require active pressure part cooling and can therefore be successfully printed with the Tantillus R.
Since the heater block is constantly exposed to the air flow of the pressure part cooling, it is advisable to use a cover made of high-temperature-resistant silicone. This ensures good insulation of the heater block, less heat radiation on the print part and significantly more constant temperatures.
The silicone parts have got separate chapter to find here.
(classic Merlin Hotend, many thanks to Gregor for the great picture;)
Further information on the silicone sock and its manufacture can be found here.
The Merlin must be converted to Bowden. Drill out the groove mount adapter here and cut in a thread. Depending on Push-Fit M5 or M6.
Screw the teflon inliner flush into the PEEK shaft.
The thermistor must be glued into the heating block of the Merlin Hotend or inserted with thermal paste. The thermopaste ages faster than the adhesive, but a glued thermistor is more complicated to replace.
It is also recommended to glue the Merlin. The melting chamber is glued to the PEEK part. Any possible leaks are sealed and unintentional unscrewing of the brass part during operation is prevented. However, the parts can no longer be dismantled when cold.
JB Weld is a good adhesive. Experience has shown that this is the most suitable adhesive as it does not become brittle even after permanent thermal loading.
Many confusing images of classic Merlin are circulating on the net. The O-ring which may be located on the airbrush nozzle must be removed. It would turn into a searing and smelly mass in no time.
Screw the melting chamber into the PEEK body with a little hand force until it hits the teflon inliner with a little pressure. The best way to do this is to mount a heater block, so that the shaft can be easily screwed in by hand. The brass part exerts pressure on the teflon inliner, which is slightly compressed. Do not screw in too strongly, otherwise the bore diameter of the teflon part will surely reduce too much.
If you happen to have a 1.8 or 1.9mm reamer, after all parts of the Merlin are firmly screwed together, calibrate the teflon inliner again from the inside with the reamer.
Those who do not have such high demands can also use a 1.9mm or 2.0mm drill.
(perfectly reamed, constant diameter and smooth surface up to the nozzle thread)
An MPX connector is recommended for connecting the hotend.
Next to the extruder there is an outlet for the cable harness of the hot end and two small holes for a cable tie. Here is a good place for the MPX connector. The assignment of the plug has proven itself over the years. Thermistor on the outer pins. Heating cartridge on the inner pins.
After everything is mounted it is recommended to calibrate the thermistor.
You can find more information here.
When heating the hot end to operating temperature for the first time, the nozzle should be carefully retightened. The same applies to all other screws on the heating block.
The Hotend is fixed in the XY Carriage with 2 screws and a printed part. The printed part presses the Groovemount of Merlin into the seat available in the carriage. This results in a play-free and firm connection.
The PEEK shaft with melting chamber and nozzle must first be inserted from above. The heating block can then be mounted and screwed on from below.
- Chapter 0 – Introduction
- Chapter 1 – Housing
- Chapter 2 – Z axis
- Chapter 3 – XY axis system
- Chapter 4 – Heated Bed
- Chapter 5 – Cooling
- Chapter 6 – Extruder
- Chapter 7 – Hotend
- Chapter 8 – Electronics
- Chapter 9 – Spool roller
- Chapter 10 – Silicone parts
- Chapter 11 – Option: Belt drive cover
- Chapter 12 – Option: Rasberry Pi Zero
- Chapter 13 – Option: UPS for the pi
- Chapter 14 – BOM / Downloads
- Chapter 15 – FAQ
- Chapter 16 – Samples
- Chapter 17 – Concluding remarks