Laser scanning of a Product

[dougmontgomery]

This is my first post-a few questions
I have a model that I made and I would like to have it scanned for cnc mold making purposes.

I will need some slight changes to the scanned product.

What is the normal process for this?

Please correct me if I am wrong-

1. Scan part
2. Make changes to 3d file
3. convert to tooling path(mastercam)

Is there any companies out there that are recommended/reasonable for the hobbyist?

Thanks in advance-Doug

[mcphill]

Depending on what changes you want, it may or may not be that easy to do. Scanned models are point clouds, and without expensive software, they are not easily "morphable". That said, it is easy to add to them by modelling up something and "adding" it to the point cloud.

I offer 3D scanning services. If you could send me some photos of the part you want scanned, and describe in more detail what you want done, I can get back to you with a quote and/or more detailed replies. You can e-mail me at mike@mcpii.com

[dougmontgomery]

Mike, thanks for the help- I look forward to working on this project with you-

Thanks for offering so many solutions-Look forward to posting our progress here-
Doug

[SteveS]

Mike,

I went to your site and it reinforced some prior knowledge I had laser scanning service. I never did the CAD, but had the service done to reverse engineer or inspect existing parts.

As your site points out, most laser scanning creates point clouds with nurbs that are used by very high end CAD systems. They normally aren't compatible with most hobby level CAD/CAM software using surfaces or solids.

Can you or someone at your site provide a layman explanation in a thread at CNCzone?

My interest is in scanned model translation to IGES, Parasolids, Rhino, Solidworks, Stl, Step and AutoCAD dxf. It would be interesting if you could scan a common coin, maybe a state quarter, and post samples in each format on CNCZone that is practical. (I am asking for a promotional freebie, not a quote.) My thought is that this would help you also in letting potential clients understand what they can expect.

Also, it was my experience (2004 - 2008) that parts that were not "dull" in color needed to be sprayed to remove refective areas. Is that still true?

Steve

[mcphill]

Steve,

Thanks for your input and questions.

The output from my laser scanning equipment is a point cloud in a "proprietary" format. It can also export the data as an STL file. STLs are easily imported in to most low end CAD/CAM packages. As you state, MODIFYING the scans is another thing all together. What I mostly do is either use the scan to recreate the part fully in a 3D package (I used SolidWorks), or I can "add on" to the STL information. It is a relatively simple task to use the scan data to create "cut through" shapes of the part, and loft it to make a surface or solid. Depending on your software package, once you import it in STL, you may be able to export it to any of the other formats you wish. There are tools in SolidWorks (which can also import the raw cloud data from my scanner) to extract areas of models as surfaces and create editable parts, but for the most part this is not a very easy or accurate process.

As for surface finish, really shiny objects can be difficult. This is easily reduced by applying talc or other matte material to the surface. When I can, I like to paint the part with matte white water based paint, but obviously the approach depends on what the object is, the final tolerances that are allowed, and what the owner of the original part would approve of. Scanning wood, foam, plaster, fiberglass, etc is very easy without any modification to the surface finish.

I have scanned a part, saved as STL, imported in to BOBCAD, created the GCode, and cut it on a $1000 router system (Fireball V90). The data created is very portable and very hobby-friendly ; )

[awerby]

But you can create an STL from a point cloud by "connecting the dots". It's pretty easy to create an STL file from an IGES, STEP, parasolid or NURBS model, but the reverse isn't true; the programs that can do that tend to be pretty expensive.

There's usually some degree of error that creeps into a scanned part. That's why, if you're trying to make a product, you'll generally want to use the scan as a reference, to rebuild the model in another program before using it to make a mold or die that must be within tight tolerances. This is where the expense comes into the reverse-engineering process. If your tolerances aren't tight, though - if this is just a concept model or prototype, for instance - you may be able to cut your part directly off the scan data.

Depending on the software you're using, it can be anywhere from easy to impossible to make changes to your STL file. Fortunately, if you are using it for a milling toolpath, most CAM programs only look at the surface of your mesh, and don't care how many separate parts are included. So the strategy of adding parts can work in some cases. However, if the changes you want to make are subtractive, this is not going to be the solution; you'd need to find a program that can actually modify your polygon meshes, or find a way to transform them into something you can edit.

Andrew Werby
www.computersculpture.com

[cjjonesarmory]

MachCloud found at the Mach3 website is a program that will convert point clouds to STL files. It's not too terribly difficult to figure out, not much in the way of help files or anything, but it gets the job done, and it's free.

http://www.machsupport.com/downloads.php

Look under "Artsoft recommended programs for MachCloud".

I've also been playing with MeshLab (have to search on the internet for it as I don't have the web address). It's a little more powerful than MachCloud, still free, but have a problem with it crashing when trying to open an ascii point cloud file. I suspect that whatever format I'm trying to open is not what it's expecting.

[dougmontgomery]

Mike, I should be able to pick up my designed plug for my RC Discus Launched glider called the Orion tomorrow and prime it in order to ship to you on Wednesday or Thursday.

here it is- good luck with the scan and I will look forward to any screenshots to come.

Doug

[dougmontgomery]

Mike, I hope this is what you need I will be shipping this out tomorrow afternoon to you Priority mail with some drawings -Thanks for your help.



Doug

[mcphill]

Originally Posted by dougmontgomery Mike, I hope this is what you need I will be shipping this out tomorrow afternoon to you Priority mail with some drawings -Thanks for your help. Doug

Looks perfect, and let me know if it is OK to post progress to this thread for others to view/participate.

[dougmontgomery]

Mike that sounds great- please post all progress.

These are my goals for this project:

1. have my personally designed part scanned so I have a 3d workable drawing.

2. Make some minor changes to the 3D drawing which includes
a. first .750" nose of pod needs to be blended better
b. scale drawing down .040 to account for auto piant and primer.
c. add on a 20" boom that tapers to .400"

3. draft negative molds(top and bottom)

4. Have molds cut out of delrin or T6 aluminum

Doug