Ten years ago the concept of having on our desks an affordable 3D printer knocking out high quality reproducible prints, with sub-mm accuracy, in a wide range of colours and material properties would be the would be just a dream. But now, it is reality. The machines that are now so ubiquitous for us hackers, are largely operating with the FDM principle of shooting molten plastic out of a moving nozzle, but they’re not the only game in town. A technique that has also being around for donkeys’ years is SLS or Selective Laser Sintering, but machines of this type are big, heavy and expensive. However, getting one of those in your own ‘shop now is looking a little less like a dream and more of a reality, with the SLS4All project by [Tomas Starek] over on hackaday.io.

[Tomas] has been busy over the past year, working on the design of his machine and is now almost done with the building and testing of the hardware side. SLS printing works by using a roller to transfer a layer of powdered material over the print surface, and then steering a medium-power laser beam over the surface in order to heat and bond the powder grains into a solid mass. Then, the bed is lowered a little, and the process repeats. Heating of the bed, powder and surrounding air is critical, as is moisture control, plus keeping that laser beam shape consistent over the full bed area is a bit tricky as well. These are all hurdles [Tomas] has to overcome, but the test machine is completed and is in a good place to start this process control optimisation fun.

Hardware-wise, the frame is the usual aluminium extrusion and 3D printed affair, with solid aluminium plates all over the place where needed. Electronics are based around a Raspberry Pi (running Klipper) with a BigTreeTech 1.4 turbo mainboard handling the interfacing. The 5W blue laser is steered over the powder surface using a pair of galvanometers, which sounds easier to get right than it will be — we fully expect there to be some ‘fun’ to control the spot size and shape as well as ensure that it stays consistent over the full area of the build surface. Definitely fun times, and fingers crossed that [Tomas] irons out the details and gets some good prints out of it soon!

Those who’ve been around here a while may remember we covered the OpenSLS project a while ago, and whilst we’re on the subject of 3D printing in alternative ways to FDM, here’s a little something about printing with metal, so long as you’re plenty patient!

If only a 5W laser is needed, I would just mount the laser head on an XY stage and call it a day. Galvanometers and mirrors are just a never ending headache, constantly drifting out of adjustment, degrading, etc. I’ll happily accept slower XY motion if I never have to adjust laser mirrors ever again!

These systems tend to heat the whole lot to very very close to melting/sintering temp so you do only need a little bit of added energy to make it happen – a small laser is quite doable, but perhaps not a small enough one to avoid ever having to play with its focusing optics or the mirror to shoot it on target…

I don’t think I’ve ever heard of one using something quite so weedy for SLS before, but its plausible (and lasers have the wonderful world of burst vs sustained power – is it a 5W laser on average but each pulse is 100000W or something equally daft but with a low duty cycle tanking its average output).

(Very worth pointing out no personal experience with these machines, I just read alot and wish I had the space to try making one, or I suppose both the space and money to buy one and try other projects that would be otherwise damn difficult, its a really cool technology)

The Dr D-Flo videos on SLS were a bit of an eye opener for me about the powder mess and health considerations. Not so keen to have one now.

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