A printer can't be better than its hotend.
(holds for plastic extrusion systems)
So it isn't surprising that a lot of effort and money is spent on this topic.
As I have learned the reprap hotend market is much more commercial than the rest of reprap. It may be true that anyone can build a printer, but not a hotend. This isn't only true because of limited skills and expensive tools (such as a lathe), but because of the knowledge about building hotends is far from being public domain.
Many builders of hotends keep their secrets, because they feel that their expenses on exploring how to make them should amortise. They fear that millions of chinese companies are just waiting to make profit by stealing the best ideas about hotends from western builders and mass producing them.
I can't say, if all those fears are exaggerated. Sharing knowledge about reprap should not be an intellectual one-way street. But restricting the share means to slow down the progress of reprap. The answer to this dilemma is DIY. Build your own hotend. Just as you build your own printer. You only need the right ideas.
These are some hotends I observe:
All Metal Hotends
|Aluhotend||An interesting hotend. The only all metal hotend I know of that comes along without a fan. I guess
achieves that by the long tube between the cooling rod and the heater block virtually allowing not very much heat climbing upwards. I only wonder if this solution doesn't lengthen the critical transition zone. What I do not like about it is the round heater block. A square bar would have conducted the heat much better towards the nozzle.
|Emaker hotend||Some ingenious work by jmgiacalone. This hotend influenced my thinking about hotends a lot. The only thing I never understood about it was the PTFE cone at the nozzle. I would have made it of brass, as it improves the heat conduction towards the nozzle. But the master decided to shield his printed part from that heat. Does it reduce warping?|
|Arcol V4.1 hotend||No comment yet.|
|E3D all metal Hot-End||The similarity to the Emaker is obvious. SanjayM was indeed influenced by Jean-Marc Giacalone's work. But I think he improved it by making it more compact.|
|Prusa Hotend||No comment yet.|
|J-Head Mk V||The J-Head is one of the most widespread hotends around the world.|