Z Signs asked me to post up in the open forum how i would create a true 3D model on a 3 axis CNC router.
First off I have a program called Aspire made by Vectric (very affordable considering what it can do) in Aspire I can actually bring in 3D models and do a 4 sided routing job that's the easy way.
For those who do not have software that will allow you to do this here is how i have done it in the past before owning Aspire.
First you need a true 3D model of whatever it is you are going to carve (remeber that under cuts are not impossible but are VERY VERY difficult to do I recommend staying away from them as much as possible).
Ok once you have your model you will need to first slice it in half so you have a front and a back or top and bottom (the direction will be dictated based on what it is you are trying to carve again trying to stay away from undercuts). you could slice it into quarters also for under cut stuff.
Ok once you have it sliced in half or quarters you will then take 1 half or quarter and slice it into several layers think of it like pancakes the higher you stake them the more of a 3D object you get.
When you slice the halves or quarters into layers you need to decide how thick of a material you are going to use ( there are several things to consider here such as how detailed is the model, how deep are the cuts, how long of a cutter will you need to reach everything etc..) a little trial and error and you will figure out what you, your cutters and your machines capabilities are.
once you have all the sides sliced up into layers you will need to save each one of those layers as a separate object and then you bring them into the software that you use to create the tool paths one at a time and create tool paths the same way you would create a tool path for a raised or relief type carving.
once all the separate objects are carved its a matter of gluing them together in the right order to create the 3D model (like pancakes one then 2 then 3 etc..)
once you have them all glued together you will need to do a little hand clean up (sand edges maybe a little foam or clay here and there etc.. until it looks good).
Then add paint.
I attached a video of Cut3D by vectric its a software program that is available by itself and included in Aspire (this is the program i use for this kind of stuff). It shows what i am talking about in the software the model is sliced up based on your parameters but you can do it yourself in any 3D modeling program just more time consuming.
[video=youtube;3ccL_rYWVCc]http://www.youtube.com/watch?v=3ccL_rYWVCc[/video]