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This is incorrect for a few reasons. 1. Limitations on geometry. CNC milling has a much smaller set of allowed geometry than 3D printing. More crucially, the l

by kaib 14y ago

This is incorrect for a few reasons. 1. Limitations on geometry. CNC milling has a much smaller set of allowed geometry than 3D printing. More crucially, the limitations of 3D printing are closer to the limitations of what a stable physical object has (no things hanging in the air). As an example, sharp inner corner are impossible to do on a CNC mill, interior details inside cavities that are smaller than the toolhead are impossible etc. 2. Tooling cost. A lot of the cost of CNC milling comes from the tooling cost, basically the work and expertise required to set up a milling operation is considerable. Many times the setup causes the original design to change in subtle and unexpected ways (how do you hold the part between milling passes?). 3D printing has no such issues, if the geometry is valid it is as easy to print as any other valid geometry. 3. CAD software. Because of 1 and 2 it's much easier to make a CAD software that targets 3D printing exclusively. There is an emerging "hobby CAD" category aimed at all the new users having access to 3D printing. This is a meta observation that "I drew in my CAD program" is often the hardest problem to solve. Here is a simple example. This was designed in roughly 30 minutes and printed out in various materials by clicking a UI button. I would be hard pressed to CNC mill this part even if I could change features like the eye sockets and mouth internal: https://tinkercad.com/things/3XaRYyuG2hd https://tinkercad.com/things/3XaRYyuG2hd Background, I've done a fair amount of CNC milling and 3D printing. I'm the co-founder of Tinkercad mentioned above. I'm very familiar with Michal's work from when I worked at Google.

jrockway 14y ago
This is incorrect for a few reasons. I don't think speculation about what will be a revolution can be correct or incorrect :) Limitations on geometry. Definitely true, though it seems to be good enough for machine parts, dental implants, jewelry, and so on. (That YouTube video of the CNC-milled chess pieces is pretty cool too.) For all the geometry advantages of 3D printing, there are also disadvantages. The materials you can use are limited. Pieces coming out of the printer require finishing work, especially at the low end. Mills are more versatile and produce mostly ready-to-use pieces. Both 3D printers and mills are inefficient for making more than one copy of a part. 2. Tooling cost. Tinkercad links to the Makerbot Replicator, it's $1800. Roland makes hobbyist CNC mills for $900. I've used a cheap 3D printer before, and it can't produce pieces that are anywhere near the quality you advertise on your site. They look like a very drunk person vaguely sketched the outline of the piece with a hot glue gun :) 3. CAD software. ... This is a meta observation that "I drew in my CAD program" is often the hardest problem to solve. I don't understand why your software can produce 3D printing instructions but not toolpaths for CNC mills. Once you've made a nice UI layer (which you have) it's just another algorithm on the backend. Anyway, I don't think the 3D printing is going to be a revolution. People can draw things and make a machine make them already. The rest is just implementation details. (2D printing was a revolution. Cheap inkjets were just a nice implementation.)
- kaib 14y ago
  Hahaa, it did come out pretty black and white, didn't it. :-) I was mainly referring to the observation that while digital manufacturing in general is considered the 3rd industrial revolution it's 3D printing in particular that's driving it. Also, if it didn't come across I really like CNC machining and I think it will have an important part in manufacturing for years to come. 1. Limitations on geometry The set of shapes that can reasonably be machined certainly contains a lot of useful items. However, the limitations that the machining process places on the design are subtle to learn and sometimes limit the process fundamentally. Of the examples you mention dental implants and jewelry are actually rapidly moving to 3D printing specifically because of geometry limitations. As an example pretty much all hearing aids are nowadays 3D printed. The geometry limitations are mostly driving adoption of 3D printing in high end applications like human implants, aircrafts, complex machine parts etc. 2. Tooling cost I think there is a slight misunderstanding. Tooling cost does not refer to the cost of the tool but to the cost of changing the configuration of that tool from manufacturing item A to manufacturing item B. For machining centers that cost is very high, think of it as the work you go through when you switch milling bits, workpiece holding, alignment etc. For 3D printers that cost is virtually zero. As for material choices I have several copies of the croco fob in question printed in steel. They were ordered through a 3D printing service and costed about $30 per piece. Aside from the fact that the croco fob can't be milled there is nowhere I could order three of them for that price. 3. CAD software/Tinkercad We could certainly add CNC toolpaths but there is a lot more people who want to 3D print than mill. Given how easy it's to 3D print through one of the printing services compared to the hassle of going through a machine shop I can't really blame them. The main benefits of CNC toolpath generation would be home machinists, like myself, who could then use Tinkercad. That group of people is pretty small. People can draw things and make a machine make them already. This is the part where we disagree. Or more properly I think your definition of people is a few magnitudes smaller than my definition of it. To use your analogy, machining is like plotting and 3D printing is like raster (matrix) printing. I think calling it an implementation detail is missing the point.
  - jrockway 14y ago
    I looked around on your site a bit more and it seems the main manufacturing method is to send it to some third party to magically print. That's fine; I'm sure someone messes around with a file at some point, but since it's not me, I guess I don't care.
bprater 14y ago
Wow, Tinkercad feels really good as CAD in the browser!

by kaib 14y ago

jrockway 14y ago

This is incorrect for a few reasons. I don't think speculation about what will be a revolution can be correct or incorrect :) Limitations on geometry. Definitely true, though it seems to be good enough for machine parts, dental implants, jewelry, and so on. (That YouTube video of the CNC-milled chess pieces is pretty cool too.) For all the geometry advantages of 3D printing, there are also disadvantages. The materials you can use are limited. Pieces coming out of the printer require finishing work, especially at the low end. Mills are more versatile and produce mostly ready-to-use pieces. Both 3D printers and mills are inefficient for making more than one copy of a part. 2. Tooling cost. Tinkercad links to the Makerbot Replicator, it's $1800. Roland makes hobbyist CNC mills for $900. I've used a cheap 3D printer before, and it can't produce pieces that are anywhere near the quality you advertise on your site. They look like a very drunk person vaguely sketched the outline of the piece with a hot glue gun :) 3. CAD software. ... This is a meta observation that "I drew in my CAD program" is often the hardest problem to solve. I don't understand why your software can produce 3D printing instructions but not toolpaths for CNC mills. Once you've made a nice UI layer (which you have) it's just another algorithm on the backend. Anyway, I don't think the 3D printing is going to be a revolution. People can draw things and make a machine make them already. The rest is just implementation details. (2D printing was a revolution. Cheap inkjets were just a nice implementation.)

kaib 14y ago
Hahaa, it did come out pretty black and white, didn't it. :-) I was mainly referring to the observation that while digital manufacturing in general is considered the 3rd industrial revolution it's 3D printing in particular that's driving it. Also, if it didn't come across I really like CNC machining and I think it will have an important part in manufacturing for years to come. 1. Limitations on geometry The set of shapes that can reasonably be machined certainly contains a lot of useful items. However, the limitations that the machining process places on the design are subtle to learn and sometimes limit the process fundamentally. Of the examples you mention dental implants and jewelry are actually rapidly moving to 3D printing specifically because of geometry limitations. As an example pretty much all hearing aids are nowadays 3D printed. The geometry limitations are mostly driving adoption of 3D printing in high end applications like human implants, aircrafts, complex machine parts etc. 2. Tooling cost I think there is a slight misunderstanding. Tooling cost does not refer to the cost of the tool but to the cost of changing the configuration of that tool from manufacturing item A to manufacturing item B. For machining centers that cost is very high, think of it as the work you go through when you switch milling bits, workpiece holding, alignment etc. For 3D printers that cost is virtually zero. As for material choices I have several copies of the croco fob in question printed in steel. They were ordered through a 3D printing service and costed about $30 per piece. Aside from the fact that the croco fob can't be milled there is nowhere I could order three of them for that price. 3. CAD software/Tinkercad We could certainly add CNC toolpaths but there is a lot more people who want to 3D print than mill. Given how easy it's to 3D print through one of the printing services compared to the hassle of going through a machine shop I can't really blame them. The main benefits of CNC toolpath generation would be home machinists, like myself, who could then use Tinkercad. That group of people is pretty small. People can draw things and make a machine make them already. This is the part where we disagree. Or more properly I think your definition of people is a few magnitudes smaller than my definition of it. To use your analogy, machining is like plotting and 3D printing is like raster (matrix) printing. I think calling it an implementation detail is missing the point.
- jrockway 14y ago
  I looked around on your site a bit more and it seems the main manufacturing method is to send it to some third party to magically print. That's fine; I'm sure someone messes around with a file at some point, but since it's not me, I guess I don't care.

bprater 14y ago

Wow, Tinkercad feels really good as CAD in the browser!