MIT team develops 3D printer that's 10x faster than comparable 3D printers • Hacker News Board

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#71

Post by crankylinuxuser » Sat, Dec 08, 2018, 6:13 PM UTC

ravedave5 wrote: post #69

crankylinuxuser wrote: post #65

I saw this 2 years ago. Long story short, you need a fiber laser and a driving circuit to do this. Sure it's 10x the speed, but it's almost 100x the price. A Creality Ender 3 is around $200. This printer, with fiber laser, is around $15-20k. And the Ender 3 can't make moves that fast. The Atmega chip is just a 16 MHz chip. You can't generate the steps required even using Klipper firmware (which is a bitbanging firmwa…

Don't forget all 3d printers were 15k not that long ago.

Unfortunately, a large portion of that was due to patent interference from Stratasys. https://hackaday.com/2013/09/11/3d-printering-key-patents/

2009 was when the patent expired. And that's when RepRap picked up rather quickly. The patent was handled since 1989 reminded me the same way the Wrights brought avionics to its knees in the US until the US busted the patent for WWI.

To make a 3d printer, all you need is a slow controller for handing gcode, 4 stepper controllers, 4 stepper motors, thermistors, heated bed, and heated tip. Worst case, before being able to buy calibrated filament, you could use weed whacker line, and put in its equivalent diameter

However, one trend I see, is that optics does not lower in price. Sure, lasers have gotten cheaper. But when you talk about 200 laser diodes at 5w each and using a complicated assortment of lenses and glass fiber optics, that stuff's $$$$$. The costs can come down from $50k to $20k, but it's still way out of the reach of 'buy on ebay or amazon'.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#72

Post by Ccecil » Sat, Dec 08, 2018, 6:24 PM UTC

jfries wrote: post #39

pontifier wrote: post #33

Earlier quoted context omitted.

I've got an unfinished 6 head printer that was intended to print 6 identical objects at a time.

Could also be used to accelerate the print of a single item by having different nozzles work at different parts of the design at once. Would need lots of updates to the slicer and solving some tricky optimization problems.

Autodesk's "Project Escher" was intended to do just that. The machine was built by Titan Robotics and uses Smoothieboards but the main issue is getting all the controllers to recognize where the other heads are in real time. Setting the CAM system to attempt to keep them all sync'ed doesn't always work as intended due to the way the firmware on the control board processes the incoming gcode.

https://www.engineering.com/3DPrinting/3DPrintingArticles/Ar...

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#73

Post by suyash » Sat, Dec 08, 2018, 6:25 PM UTC

dmritard96 wrote: post #68

I dont think I have ever read an article about MIT students that didnt start its headline with MIT, is this university policy of some sort?

It's the name that sells :)

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#74

Post by Animats » Sat, Dec 08, 2018, 6:49 PM UTC

jstanley wrote: post #63

Animats wrote: post #35

Earlier quoted context omitted.

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 14…

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

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.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#75

Post by karmakaze » Sat, Dec 08, 2018, 7:02 PM UTC

10x faster is a substantial achievement for anyone waiting for 3D items being made.

For the technology as a whole we need something that changes more than a constant factor, i.e. better than O(n^3) because we're still using filament that's time proportional to volume of the object.

This isn't entirely clear cut though. For instance laser printers technically do trace a dot of light across a page, but a single raster scan is almost instantaneous compared to the time scales of larger operations. Not having to physically move a 'print head' seems to be the winning design.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#76

Post by abecedarius » Sat, Dec 08, 2018, 8:03 PM UTC

karmakaze wrote: post #75

10x faster is a substantial achievement for anyone waiting for 3D items being made. For the technology as a whole we need something that changes more than a constant factor, i.e. better than O(n^3) because we're still using filament that's time proportional to volume of the object. This isn't entirely clear cut though. For instance laser printers technically do trace a dot of light across a page, but a single raster…

The 'obvious' way to do that: parallel heads across the whole surface, so time is O(height). Feynman brought this up in https://people.eecs.berkeley.edu/~pister/290G/Papers/Feynman... (an 80s followup to "Plenty of Room at the Bottom"):

> You should have a thicker machine with tubes and pipes that brings in chemicals. Tubes with controllable valves - all very tiny. What I want is to build in three dimensions by squirting the various substances from different holes that are electrically controlled, and by rapidly working my way back and doing layer after layer, I make a three-dimensional pattern.

Added: since mechanical frequencies scale up as size scales down, this sort of design would ideally scale as O(1). That is, with smaller parts and increasing resolution, you have O(n^2) parts, each working O(n) faster, to produce O(n^3) units times O(n^-3) unit volume = O(1) volume per unit time.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#77

Post by crwalker » Sat, Dec 08, 2018, 8:43 PM UTC

Fused filament fabrication (FFF) is fighting against physics in the same way that O(n) vs O(n^2) vs O(n!) algorithms have wildly different performance at scale.

It's a point solution, depositing ~1 voxel per unit of time. Running print heads in parallel is still O(1). Speeding up the print head runs out of steam because you run into vibration limits for the machinery (you can hear the rattling in the audio for this article). To really scale you need to deposit ~n voxels per unit of time (HP's MJF technology) or ~n^2 (Carbon's CLIP).

You need lots of voxels for high resolution for most applications. There are certain exceptions like prototyping in PETG or 3D printing concrete houses where the speed limitations of FFF may not be a big issue. But for 3D printing to compete with many forms of traditional manufacturing, simultaneous parallel structuring of matter is key.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#78

Post by syntaxing » Sat, Dec 08, 2018, 8:54 PM UTC

slededit wrote: post #4

I wonder why they needed the laser pre-heater. I can't imagine it is that dramatically more effective than resistive heating. Even if it is, just having a longer pre-heater to make up for it would have to be cheaper. EDIT: Did a bit of research, a major benefit of laser heating is direct control of energy transfer so you can be sure your heating the plastic to the right temperature regardless of how fast its moving t…

The mode of heat transfer is very important for applications like this. Higher mass flow means you need a hotter heater which can get tricky for long term usage or you'll have to use some sort of refractory or ceramic based heater. Also with conduction, the biggest problem is heat loss either due to the environment of the system . It is almost impossible to direct all your energy towards a single source with conduction. Radiation on the other hand works really well for this type of application. Especially for lasers since the energy sources is highly polarized and condensed. The other method might be to use induction heaters or microwave, but plastics do not play well with that.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#79

Post by dumbfoundded » Sun, Dec 09, 2018, 4:09 AM UTC

dmritard96 wrote: post #68

I dont think I have ever read an article about MIT students that didnt start its headline with MIT, is this university policy of some sort?

Well, if it's done by professors at MIT, it makes sense.

I run a cannabis company (cbd). My cofounder and I were roommates at MIT. We rarely mention it in our industry.

Re: MIT team develops 3D printer that's 10x faster than comparable 3D printers

#80

Post by sgc » Sun, Dec 09, 2018, 5:35 PM UTC

pontifier wrote: post #61

StavrosK wrote: post #36

Earlier quoted context omitted.

10,000 times faster at printing a single object?

The conceptual targets are printing a chair sized object from granular material in 30 seconds, and a 2 story concrete house in 1 hour, so 10,000 is a very rough "shock marketing number", but yeah.

You can't print a concrete house in a hour. It would collapse. Also, in general, the slower concrete cures the stronger it is - to the point where attempts to have it cure faster will destroy its compressive strength. Concrete walls should remain in forms at least one week and far better for two, and be wetted continuously during that period. 3d printing concrete needs a massive breakthrough in 2500 year old curing technology or it's a death wish.