10 Replies Latest reply on Dec 20, 2011 4:05 PM by John Stoltzfus

    how best to slice a model for cutting?

    Matthew Neesley

      Hello to all:

       

      I've been asked to help an artist model a child's rocking chair-type thing.  It's a small dinosaur about 3 feet tall that will be fastened to wood runners.  I am going to re-create his physical design as a 3D Solidworks model; then we are going to produce slices fron this model that can be cut on a CNC Router,  I can do the modeling just fine, but....does anyone out there have any suggestions for slicing it?  The only way I can think of right now is to use two boxes with a 3/4" space between them, which I would use to Extrude-Cut to generate the slice.  Is there a quicker/easier way?  Maybe using planes and/or section cuts?  Thanks in advance for any informed replies!

        • Re: how best to slice a model for cutting?
          Tony Cantrell

          Yes you can use planes, insert reference geometry planes, specify the distance and number of planes. Use surface cut and select the plane you need.

          • Re: how best to slice a model for cutting?
            Ryan Brumund

            Do you need 3D model slices for the router or would 2D do?  I did something similar while making a casting pattern and what I did was to put the part into a drawing and created section views showing only the cut area of all my slices.  I then cut out the pieces using the 2D sections.  I was doing it by hand, but you could export your drawing as a DXF and bring that into the router if you just doing 2D profiles. 

              • Re: how best to slice a model for cutting?
                Matthew Neesley

                The plan is to make pieces out of 3/4" mdf, assemble them and he will use bondo, etc. then sand everything into the curved contours needed.

                  • Re: how best to slice a model for cutting?
                    Randy Neumann

                    I would create offset planes .75 apart, and get intersection curves, and export them to dxf for router geometry. You only need the larger edge of each slice for 2d cutting anyway.

                      • Re: how best to slice a model for cutting?
                        Lenny Bucholz

                        Randy Neumann wrote:

                         

                        I would create offset planes .75 apart, and get intersection curves, and export them to dxf for router geometry. You only need the larger edge of each slice for 2d cutting anyway.

                         

                         

                         

                         

                        Randy it is really the lower side of each slice as that is where the bondo will fill then the next slices low side is the high side of the last one, then it will give a nice ridge to pull the bondo.

                         

                        These are old model maker tricks. A model makers best friend bondo, double stick tape, super glue and a file!

                          • Re: how best to slice a model for cutting?
                            Bevin Pettitt

                            Which side of the slice to use as the 2D profile depends whether the part tapers up or tapers down, and whether the filing/sanding is to be done on the MDF or the filling. So if you are going to sand the stock material, then the side to pick is the larger and if sanding the filler, then the smaller side edge should be used.

                             

                            But if the slice has both taper up and taper down edges then... just take your pick because you will be sanding both stock and filler.

                            • Re: how best to slice a model for cutting?
                              Anna Wood

                              I do not think Matthew is making a mold.  He is doing a skeleton model of a dinosaur chair.

                               

                              Which in his situation, he will need to make a choice depending on the shapes where he is cutting whether it is better to do innies or outies.  I suspect it will be a combination of both for seating comfort.

                               

                              Cheers,

                               

                              Anna

                                • Re: how best to slice a model for cutting?
                                  Lenny Bucholz

                                  Yes I know its not a mold have had to do this alot as a model maker when CNC and CAM weren't available.

                                   

                                  It's just like the old days when SLA's started to come into play file the lows with bondo and sand in between the high spots.

                                   

                                  And yes depending on the shape it could be either, I said lower as they could make it bigger than they want if they go to the high side first.

                                   

                                  Now if they have someone with CAM they could machine the 3\4 thickness to shape on the edges and for go the bondo, just pin glue sand spray sanding sealer, sand, spot puddy, sand, spray more sanding sealr then pray final color.

                                   

                                  or they could do a combo of thin plywood and foam, the foam will shape easier then spray an eggshell material over sand and then polyester and fiberglass matting, would be a hell of alot lighter.

                                   

                                  just some ideas

                        • Re: how best to slice a model for cutting?
                          David Suelflow

                          I would create Planes where you want the cut/slice to be (every ¾”).  On each plane, create a planer surface larger than the object.  Then I would split the part using the surface(s).  If you auto-assign names it will save each body as its own part.

                          • Re: how best to slice a model for cutting?
                            John Stoltzfus

                            Good afternoon Matthew,

                             

                            It looks like you have plenty of examples and suggestions

                             

                             

                            Reminds me of a project that I did in 2003 - 2004,  I had a Civil Engineer give us a drawing that had 3" grids to make a "N" Scale layout of a 80 to 100 acre Campground and Potential Amusement park and we made a topographical model of the entire property and used the drywall compond to blend in the slopes. We had a few buildings and a lot of trees, complete with roads and telephone poles. 

                             

                            The model size was 14'-00" x 7'-00", I wish I still had the pictures of the finished model. 

                             

                            Using N scale the 3/4" styrofoam board equals approximately 10'-00".

                             

                            Lots of fun,

                             

                            Later,

                             

                            John

                             

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