Futuristic FDM idea!

So I was considering the benefits and limitations of FDM/SLA etc. SLA trounces FDM in resolution but lacks in strength and is expensive in consumables (resin etc). I rather like the benefits of FDM though. I started thinking of ways of making FDM better. Resolution is improved with smaller nozzle diameters and layer heights, but that makes print speed unreasonably slow. I think as long as we're sticking with shoving hot plastic through a hole, in order to get the best of both worlds, the real answer is an adjustable hole! Consider a nozzle tip that can be changed with G-code from .2 to .8 in real time mid print. Crush your infill and interior aspects in .8, do your perimeter in .2. Variable layer height isn't a problem, especially if the two are divisible, ie .1 on the outside .3 on the inside, three layers around the outside for each internal lap around the print bed. You'd have to modify a slicer to support a new command for adjusting such a thing, but I'd imagine DC42 or one of the other geniuses could handle that. The hardware shouldn't be THAT hard to figure out, although I concede I have thought of a few rough methods but haven't really flushed them out in my head.

Thoughts?

There have been some attempts in this direction. But it seems to me much simpler, and much more useful, to use, on the same effector, several nozzles of different diameters, possibly with different materials.

Multiple nozzles create their own problems though, but I agree it's got use for nozzle diameter. However if you end up needing a prime tower between diameter changes, you'll lose much of the time you save, plus the oozing problems etc scares me. Shouldn't be that crazy to make a nozzle that twists to shrink the exit diameter, right?

The question is: is it mechanically simpler, more reliable and less cumbersome to exchange the nozzles, than change their diameter on the fly?
For now, the answer is clearly YES. It can only change if you propose an reliable, elegant and light solution to the mechanical question raised ...

An easy way to make an orifice that can be modified is to use an inner metal that has a lower coefficient of thermal expansion than an outer layer of metal (or other material). Just change the temperature of the outer layer to vary the orifice diameter.

How about just squirting resin through a nozzle and hardening it with UV LEDs on the extruder carriage?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I like the idea of perimeters at 0.2mm and infill at 0.8mm but the key technology would be this variable diameter nozzle system, if you can make one you've got a potentially great idea. Sounds tricky. Idex with 0.2 for perimeters and 0.8 on a second x carriage would work in the meantime. It's still not that fast unless you are just letting the second extruder ooze whilst the first does the fine detail.

Maybe we need resins that are cheap and strong.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Maybe we need to think of a way to print fdm with resins, then we get the best of both systems. Andrew

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