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Comment by thisjepisje | Hacker News Reader

What's up with the abundance of cheap extrusion printers, while (almost) no consumer-grade SLS (selective laser sintering) machines are available? The latter technology seems vastly superior to me, in terms of freedom to actually print anything you want. Is the technology that much harder?

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A lot of the technological hurdles associated with using lasers can be overcome by using a chemical bonding agent 'extruded' onto the particles by an inkjet print head. There's at least one open source printer that's trying this at the moment[1], and HP proposed a similar machine for the commercial sector[2].

The biggest issue, in my experience, ends up being that most non-metal printed parts are relatively brittle and prone to the material rubbing off if the outer layers are even lightly abraded. Ytec3D gets around this by soaking the prints with a liquid glue to solidify the bonds, but between that and the cleanup environment (compressed air, brushes, respirators) it's a hard sell for consumers.

EDIT: It's also important to note that FFF/FDM (extrusion-based) printers are getting much closer to 'freedom to print anything you want'. This year, I feel like multi-extrusion systems are going to become much more mainstream, allowing users to print more complex objects with support material that can be dissolved away later (e.g. ABS with HIPS support).

[1] http://ytec3d.com/plan-b/

[2] http://h10124.www1.hp.com/campaigns/ga/3dprinting/4AA5-5472E...

Harder, much more expensive and much more dangerous to operate. So that's why they're not more common. The last thing you want is for a machine like that to be run in a regular home without proper fume extraction. At the back of those machines you usually see a thing like a very thick vacuum hose connected to remove the (toxic!) vapors.

They also consume a lot of power, usually requiring industrial power hookups.

edit: here is a nice picture of such a setup

https://www.solidconcepts.com/content/images/repeatable-proc...

Those white tubes going up out of the machine are the extraction channels.

The fumes especially are a good point, hadn't thought of that. SLS is also possible with plastic, though, in which case I guess the fumes are comparable to those produced by an extrusion printer.

Well, almost. The SLS uses very fine grains as a base material, an extrusion printer uses a filament. The grains will vaporize much easier than filament but there is definitely a concentration of unhealthy particles in the air around an extrusion printer and I would not operate one without at least basic precautions (fume hood or something similar).

If only it was possible to hook up on single-phase house mains an arc torch-based plasma gasifier to direct those toxic fumes into. I specifically looked for access to three-phase power when choosing a residence because I don't see power consumption requirements for the metal sintering gear coming down anytime soon.

Most larger fuel powered welders have a triphase output. If you don't use it all the time that may be an acceptable alternative.

Thank you very much for pointing that out! Since such a printer wouldn't run all the time, this should be a great fit. Once biogas generators are integrated better with biogas cleaning and upgrading equipment to produce sufficiently concentrated methane to meet manufacturer specs for natural gas-powered equipment, perhaps with liquid nitrogen (highly useful for many sustainability hacking projects), then even the energy extraction externalities of such a gasifier could get quite respectable.

FYI you can use either a static phase converter or rotary converter to convert from single phase to three phase. A decent 20A three phase static converter will run you about $500. Much easier than trying to find a house with three phase!

Yes, good point, thanks for pointing that out. I did look into phase converters, but at the time was considering continuous usage of three phase power, due to the energy losses. Of course with an infrequently-used 3D metal sintering printer, it becomes much more practical to deploy a phase converter for just the printer's gasifier. Bonus: the well-built digital controlled rotary phase converters can last 30+ years, and from my poor electrical ed-shu-ma-ka-shun I understand these better ones yield a true analog sine wave good enough for even very sensitive electronics.

mostly because of patents. but changing this year. here is one company http://www.norgesystems.com/

That's exactly it - last time I checked SLS seemed to be around 5 years behind that of FDM. SLS is also a more complicated process to get good results out of and certain patents for improvements (such as a Nitrogen atmosphere) are yet to expire.

I guess extrusion printers need to become a widely used product so that companies look to make SLS more affordable to the public.

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