3 ms·

Very cool, but big caveats as usual from a uni press piece. However, they ran up against a small glitch in their speedier design: The extruded plastic is fed t

Very cool, but big caveats as usual from a uni press piece. However, they ran up against a small glitch in their speedier design: The extruded plastic is fed through the nozzle at such high forces and temperatures that a printed layer can still be slightly molten by the time the printer is extruding a second layer. “We found that when you finish one layer and go back to begin the next layer, the previous layer is still a little too hot. So we have to cool the part actively as it prints, to retain the shape of the part so it doesn’t get distorted or soften,” Hart says. That’s a design challenge that the researchers are currently taking on, in combination with the mathematics by which the path of the printhead can be optimized. They will also explore new materials to feed through the printer.

jstanley 9y ago
> So we have to cool the part actively as it prints, to retain the shape of the part so it doesn’t get distorted or soften This is a (solved-ish) problem even on current-generation commercial printers. It's called a "part-cooling fan". It sits next to the hot-end and blows air on the plastic as it comes out of the nozzle. Here's a dual-fan example: http://www.akeric.com/blog/wp-content/uploads/2015/07/filamentCooler2.jpg http://www.akeric.com/blog/wp-content/uploads/2015/07/filame...
- QAPereo 9y ago
  Apparently it can’t scale up 10x or more though, at least with current materials.
  - deelowe 9y ago
    Could this be solved by adding refrigeration? Couldn't they run the machines much faster if it was printing in a colder environment?
    - valine 9y ago
      It probably depends on what material you’re printing with. Keeping ABS from warping in a cold environment would be difficult or even impossible. At the very least it would put new limitations on what shapes are possible to print and constrain your options when it comes to infill.
    - ggcdn 9y ago
      You get a worse bond if it's too cold. as the plastic cools it warps and can crack along the interface between layers. Plastics like abs usually require a heated print bed as well. I think the ideal solution would allow the entire piece to stay at a elevated temp somewhere between ambient and melting, but blow cool air over the freshly extruded plastic to quickly bring the temp down from the melting point
valine 9y ago
That’s a problem with most 3D printers I think. I usually get around it by printing multiple copies of the object at the same time. By the time the printer gets around to the first copy it’s cool enough not to cause issues. Obviously it’s a much harder problem to solve the faster you print.
- alanfalcon 9y ago
  Doesn't work as well when you just want to pop out a quick small prototype so you can test it, iterate, and do it again, but definitely that works for some applications. And as they mention, path optimization can also help here. As a contrived example, if you're building an upside down extruded "T" shape, maybe you could work on building up the stem as high as possible as quickly as possible, and spending the "cooldown" time working on extending and building up the base. I'm not aware of any 3D printers that move beyond the simple "build from the bottom up" approach[1], but it seems possible to take into account the bulk/size/shape of the printhead and do some advanced things -- if the payoff is there. [1] I also know approximately nothing about this space, I'm not speaking from an area of expertise, just novice theory. Maybe this is already being done or maybe it's simply impossible because the printhead is just far too bulky.
  - valine 9y ago
    There are some experimental 3D printers that deviate from the “build from the bottom up approach.” Here is a pretty cool 5 axis 3D printer: https://m.youtube.com/watch?v=w8Fl8L4yk8M https://m.youtube.com/watch?v=w8Fl8L4yk8M
    - SAI_Peregrinus 9y ago
      Or production devices. DMG Mori makes a ($250,000) 5-axis CNC that can do 3D printing (selective laser sintering). Example: https://www.youtube.com/watch?v=1TwVkAuvGwM https://www.youtube.com/watch?v=1TwVkAuvGwM
- StavrosK 9y ago
  The other alternative is to pause the head while the layer cools down. Most slicers have an option for that, although it does increase print times.

jstanley 9y ago

> So we have to cool the part actively as it prints, to retain the shape of the part so it doesn’t get distorted or soften This is a (solved-ish) problem even on current-generation commercial printers. It's called a "part-cooling fan". It sits next to the hot-end and blows air on the plastic as it comes out of the nozzle. Here's a dual-fan example: http://www.akeric.com/blog/wp-content/uploads/2015/07/filamentCooler2.jpg http://www.akeric.com/blog/wp-content/uploads/2015/07/filame...

QAPereo 9y ago
Apparently it can’t scale up 10x or more though, at least with current materials.
- deelowe 9y ago
  Could this be solved by adding refrigeration? Couldn't they run the machines much faster if it was printing in a colder environment?
  - valine 9y ago
    It probably depends on what material you’re printing with. Keeping ABS from warping in a cold environment would be difficult or even impossible. At the very least it would put new limitations on what shapes are possible to print and constrain your options when it comes to infill.
  - ggcdn 9y ago
    You get a worse bond if it's too cold. as the plastic cools it warps and can crack along the interface between layers. Plastics like abs usually require a heated print bed as well. I think the ideal solution would allow the entire piece to stay at a elevated temp somewhere between ambient and melting, but blow cool air over the freshly extruded plastic to quickly bring the temp down from the melting point

valine 9y ago

That’s a problem with most 3D printers I think. I usually get around it by printing multiple copies of the object at the same time. By the time the printer gets around to the first copy it’s cool enough not to cause issues. Obviously it’s a much harder problem to solve the faster you print.

alanfalcon 9y ago
Doesn't work as well when you just want to pop out a quick small prototype so you can test it, iterate, and do it again, but definitely that works for some applications. And as they mention, path optimization can also help here. As a contrived example, if you're building an upside down extruded "T" shape, maybe you could work on building up the stem as high as possible as quickly as possible, and spending the "cooldown" time working on extending and building up the base. I'm not aware of any 3D printers that move beyond the simple "build from the bottom up" approach[1], but it seems possible to take into account the bulk/size/shape of the printhead and do some advanced things -- if the payoff is there. [1] I also know approximately nothing about this space, I'm not speaking from an area of expertise, just novice theory. Maybe this is already being done or maybe it's simply impossible because the printhead is just far too bulky.
- valine 9y ago
  There are some experimental 3D printers that deviate from the “build from the bottom up approach.” Here is a pretty cool 5 axis 3D printer: https://m.youtube.com/watch?v=w8Fl8L4yk8M https://m.youtube.com/watch?v=w8Fl8L4yk8M
  - SAI_Peregrinus 9y ago
    Or production devices. DMG Mori makes a ($250,000) 5-axis CNC that can do 3D printing (selective laser sintering). Example: https://www.youtube.com/watch?v=1TwVkAuvGwM https://www.youtube.com/watch?v=1TwVkAuvGwM
StavrosK 9y ago
The other alternative is to pause the head while the layer cools down. Most slicers have an option for that, although it does increase print times.