Flat Perspective

I run a CNC Router and I have been getting a bunch of 3d files lately. My software only opens 2d files so downloaded the trial of this program. I will only need this program to open 3d files for me and convert them to a flat drawing. I have been playing with the program and found the Make2d option and the flatten surface option but both of those do not give me a accurate flat part. Is there a different way I can do this so I get an accurate flat file that matches the assembly drawing I have for this part? I appreciate any help with this

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We’d need an example of what you’re trying to “flatten” that’s not turning out accurate.

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Unroll surface (explode off) will flatten developable surfaces.

Rhinoceros Help?

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I tried the flatten unroll developable surfaces and the overall size matched my drawing but the round holes were more like squares with radius corners and some of the radius did not match up with the drawing. I did not try with explode off but I do not know how to do that. I have only been using this program for a few hours and I see this program has a ton of great features.

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Exactly what kind of geometric entities is it that you need? i.e. lines, curves, poly lines, poly curves etc…

Generally I don’t think it’s a good idea to just ‘smoosh’ or ‘smash’ 3D entities into 2D flat land.

Silhouettes and mesh outlines could also need rebuilding, depending on the design intent – it’s better to not assume a particular entity is ready for toolpaths if shortcuts are made generating them from higher dimensions.

What are you working on? Routing what? Why have you been sent files that haven’t already been prepped for 2d?

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I use lines, curves, poly lines… It all depends on what the customers parts. If you dont think smooshing or smashing the 3d files into a 2d file, do you have any other suggestions. Some of my customers only supply .stp files with no drawings or pdf’s and getting them to give me one or the other is like pulling teeth. So I am hoping that there is a way to convert their files to a 2d image that I can use.

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I work in the plastics field and route a variety of materials.

Hmm but I don’t understand why you’re being sent apparently random 3D files to do 2D operations on. What do they look like? If they’re flat, then you can just extract flat surfaces, if they’re not…what the heck are they expecting you do to? You’re gonna need to send someone something, privately if you don’t want to post customer work here…just give us a section of something?

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If you are cutting flat parts from 3d objects that are in fact flat, you can run dupedge to generate curves from the edges of the surface You are trying to cut.

Extractsrf is good for pulling surfaces out of a model and join to re connect them into logical parts (poly surfaces)

Once you extract the curves with dupedge, you can feed them to your router as a def (use cam imperial or cam metric as the output style) or Ives if your cam software will accept it,

I prefer Iges over dxf personally.

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Mostly because our sales people dont know how to tell the customers that we need 2d files. They dont understand what goes into creating a file to run parts. Here is a common part I have to run
INNER SIDE RAIL - RH - RH HDPE.stp (249.4 KB)

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Okay so that’s simple enough, you just need to orient it on to the top plane by rotating it, and then you could use ExtractSrf to get the top or bottom face and then DupEdge to get the curves. I wouldn’t use UnrollSrf on surfaces that aren’t curved. There is a command for ‘remapping’ flat object on to the cplane, but…you should learn the basics of Rhino a bit more before skipping to that, it’s easy enough to just rotate and move.

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It depends on the geometry and the CNC system. Also the tolerances to the original data, etc.

Thanks, I will give that a try

Thanks I will give that a try. I appreciate your help

Tony, looks like you’ve gotten a couple useful answers here already but I thought I’d chime in since we do a lot of what you’re trying to do here at our shop. Ie, 3d models (usually made internally) sent to CNC router or CNC plasma cutter.

Looking at the sample part you sent here, my first surprise is that your client was nice enough to send it to you floating in the middle of space on a tilt, very annoying for the cutting you’re trying to do.

Re: Make2D, folks here are correct that that’s not a great way to get the vectors you’re looking for. But… if you wanted to, use that it just requires a little more set up.

  • Set your viewport to Isometric (Southeast is my default to get started, but any of them will work), All your projections from Make2D are going to be wrong if you leave your view in either perspective mode.
  • Explode the block, just select the part after opening and type ExplodeBlock
  • Now you can run OrientCameraToSrf, and when prompted select the face of the part that represents/contains the flat vector you’re trying to extract, this will set your view to the ‘flat perspective’ you’re looking for
  • Finally, select your part and run Make2D, this will throw your vectors down on the flat CPlane which you can export as a .dxf or whatever file type you need.

This is easy if you are an experienced Rhino user. It could take you all day if you don’t know all the secret handshakes.

The first thing you should do is select the object run the explode command 3 times.
This gets rid of the 3 layers of blocks that came with the import.

Now you can get at the geometry. A 4th explode will get you down individual surfaces.
You only need one of the big surfaces you could delete or hide the rest. .
Then from the front view you will need to rotate the surface. You will need to use Osnaps (object snaps) to do the rotation accurately.

Run the rotate command and snap to one edge as the center point and another point on the same edge as the first reference then drag the part down to horizontal. Hold the Shift key down when you get near horizontal position it will automatically lock it to perfectly horizontal at that point you make the second mouse click to finish the rotation.

Now that it is horizontal to the XY plane go to top view and run the DupBorder command and you will have all the 2d curves that you want.

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Jim, quite right about the block issue. Thanks for saving me the effort of trying to walk though orienting this part flat, I was just going to give a breakdown on some thoughts about how to do this “right”.

My two cents on this part in particular would be to just say screw trying to rotate it and run an Orient3Pt, but that takes a bit more explaining in text format.

For Tony’s reference, the reason he’s going to want it down on the XY plane is that if you pull those vectors off that part and immediately export them as dxf, they’re going to show up in the 2D program (cam software or otherwise) as the top down projection of those curves just as they were floating in space.

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Yeah, there are a lot of ways to do this in Rhino.

My preference would be to use the command RemapCplane. First use Cplane Object and then RemapCplane to lay it flat. That sounds easy but if your not well-versed in Rhino cplanes and viewports you can get tangled up just as easily.

Auto Cplane set to sticky and the remapcplane command will make short work of orienting.

Stick an auto cplane to any flat surface, then run remapcplane then click in a corresponding viewport to make the original cplane remap to the one you choose.

For instance, in perspective, with auto cplane enabled sub object select a flat plane on the top of the model that is oriented askew…

Then run remap cplane and click in the top viewport (do this whole operation in a 4 view set up)

The auto cplane will remap the part to the top cplane and will orient you in world space with a click or two-

Whatever orientation the part had to the original cplane will translate to the remapped cplane

It’s a super powerful feature not many people know about.

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