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Two sided 3d that's not symetrical

PostPosted: Thu Nov 03, 2016 6:00 pm
by chrisprouty77
Hey all,

I am attempting to 3d cut an airplane propeller model (for d├ęcor only) and want to make it double sided and "lifelike" meaning the pitch of the blades is tapered on both sides. I hope that's clear. The problem is that the model is not symmetrical. So if I just use the same 3d cuts on both sides, it messes it up. If I flip the 3d model, I end up with an incorrect looking propeller. The file came from Design and Make. I could not find another model and I do not have Aspire to create my own. Is there a way to make this happen that I am not seeing? Or is it impossible with VCarve only? Anyone happen to have a symmetrical 3d propeller file in their archives?

Thanks!

Re: Two sided 3d that's not symetrical

PostPosted: Thu Nov 03, 2016 8:52 pm
by adze_cnc
chrisprouty77 wrote:So if I just use the same 3D cuts on both sides, it messes it up.


Then don't use the same cut. Create separate paths for each face.

Having said that, though, the model should have rotational symmetry. That is rotate the work-piece 180 degrees (end-for-end) after the first cut before flipping it over and you should be able to use the same tool-paths on the second face.

Re: Two sided 3d that's not symetrical

PostPosted: Fri Nov 04, 2016 12:13 am
by chrisprouty77
adze_cnc: thanks. Now I feel silly. My brain just wasn't wrapping itself around it, but now it makes sense. I was missing the rotate step in the process.

Re: Two sided 3d that's not symetrical

PostPosted: Fri Nov 04, 2016 5:39 pm
by adze_cnc
Chris,

Glad to help. What a propeller does should have been a clue. :D

People wonder why I keep all sorts of tchotchkes, such as a maple seed, around my desk. A tangible object makes demonstrating concepts to people easier than sketches.

Steven

Re: Two sided 3d that's not symetrical

PostPosted: Fri Nov 04, 2016 10:46 pm
by chrisprouty77
I just realized that won't work. If I rotate and flip, I get the same result. I basically need the bottom of the model, which doesn't exist. Is there a way to "inverse" the 3d model?

Re: Two sided 3d that's not symetrical

PostPosted: Sat Nov 05, 2016 2:00 am
by eph210
There are a number of propellor files in STL format available at places like grabcad and thingiverse. Choose one that you like and import it into V Carve Pro. At the bottom of the import screen is a button labelled create both sides. Make sure that is selected and both sides will be created and placed on seperate layers. It might look a little weird to start because both layers will be visible.
There is a tutorial on importing 3d files that can help to understand the process. http://support.vectric.com/tutorials/V8 ... D_GEN.html

Euan

Re: Two sided 3d that's not symetrical

PostPosted: Sat Nov 05, 2016 2:13 am
by chrisprouty77
Thank you eph210!!!

Re: Two sided 3d that's not symetrical

PostPosted: Tue Nov 08, 2016 2:44 am
by chrisprouty77
Ok...I've been working on a solution and I'm getting closer, but I need help thinking through my next idea. I found a 3d file and used it to generate both sides from the center of the model. Didn't work because it had some undercuts that didn't get machined Photo #1 shows this. Next, I used the same model and moved the zero plane to the lowest point of the top side and generated the tool paths. I then started a new file and did the same thing to the underside. Photo's #2 & #3 below show where the zero plane is when I generated the model of each side. This worked and I got a two sided propeller, but it was really thick (photo #4). So now I'm trying to figure out how to thin it out. I figure it's all in my math somewhere and where I set the material thickness as well as the model height of each side. My ideas are 1) set the gap above model so that it lowers the model into the piece more. For instance, If the current prototype is .5" too thick, set the gap at .25". Or 2) Set the zero plane at the bottom and generate the tool paths for each side. If the total model height equals the material thickness, I should get each side...right? Just trying to wrap my brain around 2 sided machining. I wish there was a way to preview it in VCarve. Maybe a plugin or something?

Any help is greatly appreciated. I'll probably try these two methods tomorrow and post my results. But if anyone can think of what I'm missing, I sure would be grateful.