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# modeling a iaito.....

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## modeling a iaito.....

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## Re: modeling a iaito.....

 It is not so difficult to model. In principle you need a function that parametrically describes the iaito's cross-section as a polygon, with N points (i.e. a 2D-shape) and another one that describes the curve along which this parametrized shape will be extruded (by sweep). If you further employ an interpolation scheme like nSpline or Bezier, it is enough to feed just a couple (4 or 5) of polygons into the scheme ... But to be honest, I doubt that your woodworker will be able create a steel knife with a CNC. The art of black smithing has a very long tradition. -- Sent from: http://forum.openscad.org/_______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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## Re: modeling a iaito.....

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## Re: modeling a iaito.....

 linear_extrude() and rotate_extrude() will not be very helpful for your "specific" use case. I can guide you for further steps. The following code is an example for a parametrized shape function: function swordCS(D=100, d = 10, f=.8) = [[-D, 0], [-D/2, f*d], [0, d], [D/2,  f*d], [D, 0],  [D/2, -f*d], [0,-d], [-D/2,-f*d]]; you can use it (in principle) to describe a sceleton to be skinned by a sweep()-function: for(i=[0:4])   rotate([0, i*i, 0])   translate([0, 0, i*200]) polygon(swordCS(-i*15+100, 7-i)); the sweep function expects a list of polygons. You need a second function that builds this list. It calls the parametrized shape function and places the shapes into 3D by applying a translation and and a rotation (note: all "unknown" functions like Ry, Tz and vec3 are provided by a libary like Naca_sweep.scad) function sword() = [for(i=[0:.1:4.001])   Ry(-i*i,   // rotate function   Tz(i*200,  // translate function     vec3(swordCS(-i*15+100, 7-i)))) ]; finally you call the the sweep-function (also provided by the library) sweep(sword()); and you get: Thus your full code will be (in principle) as simple as the following: use  // download from https://www.thingiverse.com/thing:900137sweep(sword());   // skin the sceleton function sword() = [for(i=[0:.1:4.001])   Ry(-i*i,  // rotate   Tz(i*200, // translate     vec3(swordCS(-i*15+100, 7-i)))) // parametric call ]; function swordCS(D=100, d = 10, f=.8) = [[-D, 0], [-D/2, f*d], [0, d], [D/2,  f*d],  [D, 0],  [D/2, -f*d], [0,-d], [-D/2,-f*d]];   -- Sent from: http://forum.openscad.org/_______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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## Re: modeling a iaito.....

 In reply to this post by bboett On Wed, Apr 15, 2020 at 11:05:08AM +0200, Bruno Boettcher wrote: > hmmm.... > so in the function i need to compute the crossesction at each point of the > sword? > i have no idea on how to use bezier in openscad?? > rotate_extrude will want to extrude along a circle? and linear_extrude > along a line..... neiter will do the job? Correct! But... Just yesterday I asked about a specific shape (parabola) that needed to be extruded (with a circular cross section). The replies included two different ways to "extrude along a path"! Check out the replies to my "parabolic tube" question!         Roger. -- ** [hidden email] ** https://www.BitWizard.nl/ ** +31-15-2049110 ** **    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233    ** The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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## Re: modeling a iaito.....

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## Re: modeling a iaito.....

 In reply to this post by bboett Most knives are made on CNC machines these days, and while I appreciate and respect the craft of blacksmith (and will never forgive my father for selling my grandfather's anvil), iron, steel, alloys, and heat-treating are very well understood these days, and one can make a quite nice knife, even with just a desktop CNC: https://www.youtube.com/watch?v=2_DnkEnhZPM (see the balance of that video series for the actual process of manufacture) William _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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