Easier way to use CNC? Using a $3k 3-D Scanner with a Model

[MitchJi]

Hi,

Would it be easier for a beginner to build a physical model of what they want in wood or foam or plastic, scan it with this $3k 3-D scanner and feed the results into a CNC Machine directly rather than learning to program a CNC Machine?

Jay Leno uses this 3-D Scanner($2,995):
https://www.nextengine.com/indexSecure.htm

He describes its use here (the video is pretty amazing):
http://www.jaylenosgarage.com/extras/articles/jay-lenos-3d-printer-replaces-rusty-old-parts-1/

Some excerpts:

So, rather than have a machinist try to copy the heater and then build it, we decided to redesign the original using our NextEngine 3D scanner and Dimension 3D printer. These incredible devices allow you to make the form you need to create almost any part. The scanner can measure about 50,000 points per second at a density of 160,000 dots per inch (dpi) to create a highly detailed digital model. The 3D printer makes an exact copy of a part in plastic, which we then send out to create a mold. Some machines can even make a replacement part in cobalt-chrome with the direct laser sintering process. Just feed a plastic wire—for a steel part you use metal wire—into the appropriate laser cutter.

The plastic part is only used to be sure its correct:

The scanner allows you to make an exact copy in plastic, fit it and see that it’s correct.

But the plastic copy isn't necessary and might be overkill for many relatively simple Ebike parts:

Or you can do what we do—input that program into a Fadal CNC machine; it reads the dimensions and replicates an exact metal copy.

 

[kerosene]

you have to see beyond marketing.

1st - 3K$ for scanning hardware, then 3K$ for can helper software that helps re-creating the 3d-model from the scan. The scan itself is typically just a huge cloud of points in the shape of an object. If you are ok with approximate solution I think these days you can use polygonal triangulated mesh for CNC - I know for printing meshes are fine. Then you take the 3d model into master cam or similar cam software where you program the CNC machines routing.

In short - the scanner only helps you in creating a 3d-model. Its not quite plug and play to get a machined piece out of a scan. My experience might be a little dated but I think you still need to know what you are doing in terms of getting the CNC mill going on.

You can get pretty good polygon modelers for free (blender), NURBS modeler Rhino 3D is pretty cheap - I think +- 1000$. I would claim that depending on parts you could learn pretty quickly to create 3d-models easier than physical ones.

 

[jag]

Scanning and modelling is somewhat complementary. Often a combination of both are employed for good results. I worked with animation and anything I scanned would be imported into a modelling program (blender or maya) to be touched up. positioned as a part on an object (and if desired then animated).

The infomercial on the web link was not really informative. The scanner loked like a copy of a common Minolta scanner. Professionals are not impressed with this scanner, but maybe it is good enough for some uses. The 3D scanner in our lab is accurate to about 0.1mm, articulated on a faro arm, but cost $80k or so.

A dense and accurate point cloud really helps when computing clean surfaces. This is usually done with a ball pivoting algorithm. This requires points that should be integrated into a surface to be strictly less than the ball radius distant, and points that should not must be outside of the ball distance. (Otherwise lots of manual cleanup is needed). So if the scanner is inaccurate it is difficult to get good surfaces. A better way to get a surface involves defining a vector field pointing inwards on the 3D points and then solve a PDE for a consistent surface. This is called Poisson surfacing. I'm not sure if it is implemented in any commercial software, but the code is here: http://www.cs.jhu.edu/~misha/Code/PoissonRecon/

There is a free 3D SW meshlab:
http://meshlab.sourceforge.net/

Blender is also free as mentioned.

Some German students/researchers also showed how one can use a webcam and a laser pointed to make a nearly free laser scanner. Not sure if it is good though, and couldn't find the link.

It is also possible to make somewhat decent models from images alone, though this is really more intended for rendering applications:
http://webdocs.cs.ualberta.ca/~vis/ibmr/
http://www.arc3d.be/

 

[kerosene]

Mitch - what kind of parts do you want to fabricate? If they are relatively simple mechanical designs I would definitely go 3d-modeling route. For tricky freeform stuff like bodypanels scanning might make sense.

h