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Comment by aeleos | Hacker News Reader

It’s definitely possible that you couldn’t reach the speeds that they are with any kind of traditional heater cartridge. You need a lot of power directly on the filament to melt is at quickly as they are.

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Titan 3D Robotics has a extruder that claims to be able to print 1 pound of filament an hour which for ABS would be able 400 cm^3 (I think?)

I believe it's water cooled but still looks to be using traditional heater cartridges.

Specs: http://www.titan3drobotics.com/atlas/

Video: http://www.youtube.com/watch?v=mKPKIGcrlFU

Right. That's what you get when you build a 3D printer like a CNC machine. Titan takes in pellets directly, rather than bothering with filament. They probably use a heating system and drive screw like an injection molding machine. They can print with more plastics than filament printers. They end up with a lot of moving mass on the print head, but that's what big motors and controllers are for. The Titan unit uses 14KW of power.

I'd once considered heating the surface to which you are bonding with a laser, just ahead of the extruder, so you weld hot surface to hot surface, not hot surface to cold surface. That's why filament type 3D printers make such weak joints between layers.

I think the 400cm^3 figure was for the non-pellet version while the pellet version can use 10mm nozzles and extrudes a ridiculous amount more. I wish there was more published information about both of their extruders, they look quite interesting.

I'm guessing that absurd power requirement is for the 85C heated enclosure variant, otherwise I'm no idea where the 60amps are going.

I remember reading about a slicer with an option to use the hotend just as a heat source that traced the previous layer to smooth/blend it. Using a laser may be a good method of improving the surface finish as well.

What is the $ per kilogram cost difference if you can buy bulk PLA plastic pellets vs. buying filament on a roll? For a benchmark comparison figure the generally well-reviewed Monoprice filament ranges from $18 to $20 per 1kg spool.

it's about half as expensive.

What's the best way to keep the laser pointed just in front of the nozzle?

Not the parent commenter, but I imagine mounting it so it rotates around the nozzle’s axis would work. Fiber optics would help if the laser unit is too big to have swinging around on the print head.

You might also need to be able to tilt the laser up/down to vary the distance from the nozzle.

It should be pretty easy from there to have the computer keep it pointed at wherever the nozzle is going next.

I was thinking 3 lasers 120 degrees apart, turned on as needed, rather than a mechanical solution. 5W laser diodes would probably be enough power.

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