3d Modeling - Need general guidelines for CNC router setup

[cmurdo]

Hi,

I've got some highly detailed car models that I want to simplify for a CNC router. I liked to get some more info on a few things. Btw, I'm using 3d Studio Max, but I figure the concepts are the same as in Rhino.

The models are comprised of multiple objects(or meshes). I can easily attach all the objects together, but do I need to weld all the vertices together where the objects meet? This would basically created a continuous mesh. It's tedious work around the front grill and rear bumper areas, so I'm wondering if I need to do this.

I haven't been able to find a good resource giving guidelines or 'best practices' for modeling for CNC routers, either. Anybody know some good links?

Thanks,
Chris

[myxpykalix]

My assumption is, that you want to have a copy of the car made on the CNC as a whole object as opposed to making individual parts and then putting it together correct?

If so then you need join the parts together to make one solid object as in a STL file. I don't think you would need to weld all the vertices together so long as the parts are close enough together so as not to show gaps where the program would consider that something like a hole and want to go down into it.

There is some vectric programs like Cut3D that will do 4 sided machining, making toolpaths for cutting top, bottom, left side, right side. You would need to find someone with that program to make toolpaths for you.
Here is one resource you can read:
http://www.vectric.com/products/cut3d.html
You can download a trial and load up your object and see if it will do what you are wanting to do then find someone who owns it and pay them to make your toolpaths and cut it for you.

You didn't say how big you wanted your model to be but there is other ways to do this called slicing and other programs that do that. While at the link do some reading on other programs there.

[rej]

the master at this type of work is Jamie oxenham at www.oxenhamdesign.com (http://www.oxenhamdesign.com)
he can do whatever you need and he is a vectric user.

[ssflyer]

Not sure about the details but 3DS Max has a STL Check.

"To create a physical model, an STL file must have a complete and closed surface. Using STL Check to test your geometry before you export it can save time and money when the file is used to create the physical model. "

HERE (http://docs.autodesk.com/3DSMAX/15/ENU/3ds-Max-Help/index.html?url=files/GUID-683E0312-F28B-46E4-860E-BDFE92B6ABBE.htm,topicNumber=d30e517708) is a link describing it, if needed

[cmurdo]

Thanks for the responses!

I'll experiment with the .stl exporting.

[hespj]

"..............but do I need to weld all the vertices together where the objects meet?"

In my experience no. Not for a cnc router anyway. You would for 3D printing. For a ShopBot as long as there isn't a gap so large that the router bit would start to go into the gap you'll be okay.

[Brady Watson]

John is correct. The model can be comprised of multiple meshes that overlap & they do not need to be closed. MAX should have a boolean weld function if you did want to make it one entity. You can just export the meshes you select out of MAX and import them into CAM for toolpathing as-is. Same deal goes for Rhino.

-B

[cmurdo]

Thanks again guys. I did not need to weld the verts together for the CNC router. I sent the model to Shopbot for some tests(they're good like that when you're about to drop $20-40k on a new router). They requested a .3ds file, but unfortunately that file type limits the poly count to ~65k. I sent a .obj file and that is working fine, apparently. I'll post an update when we get the finished model.

I'm also working with them trying to establish best methods of taking a highly detailed digital model and creating a scaled-down, lower detailed physical model. Well at least from the digital modeling side.

[hespj]

I don't usually use meshes but I think there's a simplify mesh command in Rhino isn't there?