Organ Pipe Hotend
This page describes the Organ Pipe Hotend.
The Organ Pipe Hotend derives from its precessor, the Longsword Hotend.
While the Longsword Hotend has a PTFE liner inside the Cooling Bar, the Organ Pipe is a full metal hotend with a continuous barrel from the top of the cooling bar down to the nozzle. Nozzle and barrel are virtually one piece, although the barrel is made of stainless steel, while the nozzle consists of brass. Nozzle and barrel are referred to as the Pipe.
The Pipe can be exchanged very rapidly, allowing swift changes of material types (e.g. from ABS to PLA) without having to clean the barrel each time.
The Organ Pipe Hotend can be made without any lathe. A drill press will do.
The pipe consists of 3 parts:
1. A 70 mm tube of stainless steel with 4 mm OD and 3.3 mm ID.
2. A M4 acorn nut made of brass
3. A 10 mm long M6 threaded rod made of brass
Drill a 0.5 mm hole into the dome of the acorn nut. Usually I do this by screwing a 40 mm M4 threaded rod into the nut. Then I put the threaded rod into the chuck of my drill press and place a 0.5 mm PCB drill under the acorn nut. For holding the drill I use a mini chuck which I bought at a watchmakers supply shop. The chuck has a shaft which I fixate in a small vice. I use approx. 600 rpm when drilling the hole.
After drilling the hole you have to drill the M4 thread away. I use a 4.1 drill for that. Usually I sink it 5.5 mm into the acorn nut. Now your nozzle is ready.
Next drill a 4.1 mm center hole right through the M6 threaded rod. Put the threaded rod into the drill press and the drill in a vice below. If available use a center drill first.
Now you have to solder the three parts together. I use a small blowtorch and some soldering paste for that. At 610°C the solder melts. It isn't difficult at all. But be careful not to burn yourself. I drilled a 4.1 mm hole into an aluminium cube and put the cube into a vice when soldering. The hole holds the stainless steel tube.
It is a good idea to make more than one pipe as you may want to change between different nozzle diameters or types of material.
The Cooling Bar
The cooling bar consists of two parts:
1. A aluminium square profile 10 x 10 x 58 mm.
2. A brass M6 threaded rod 40 mm.
Here you see a cut through the cooling bar.
Later the bar will hold the pipe which is just clamped into the "chuck" allowing very rapid changes of pipes.