How to Model a Knife in Rhino

Step-by-Step Guide

1. 1

   Step 1: Open a new document

   Repeat for downwards direction.
   
   Delete the original curve., Then move a few control points inwards to create a similar shape as to what seen in the picture at the back of the handle.
   
   Repeat identically for the bottom curve.,,,,,, The following edges are made with the edge surface function:,, (repeat for the bottom),, Do the same for the bottom.,,, Use PlanarSrf to create a surface. repeat for the bottom.
   
   Now the outer shell of the handle is almost done !, Delete the circle surface to make a hole in the surface.,,, This will make the hole for the pivot pin so make sure you keep in mind the tolerances for moving parts.
   
   Split the surface and delete the middle circle surface again.,, Select the top half of the handle and set it to "handle top" and the same for the bottom half on "layer bottom".
   
   This will come in handy later., Switch to top view and start tracing the knife blade using curves as shown., Then move it down about 1mm (which is the minimum wall thickness for a 3D printer.
   
   Make sure it still fits between the handle shells and take care you allow tolerances for the moving parts.,,,,,, This curve should be on the same height as the top of the blade which is not closed as it will form the sharpened side of the blade.,, This will form triangles which we can close with a PlanarSrf.,,, Do this for both sides naturally.
   
   Extrude the hole from side to side.,, draw a line as shown., To do this we have to rotate the blade as if it were tucked into the handle.
   
   Use the rotate tool to rotate the blade to the desired position around its pivot point.,,,, Once this is done make sure to split the surface to open the hole for the pivot.
   
   Repeat this for the top half of your handle and you are done! All that is missing is the pivot bolt, but that should be pretty straightforward from here on!,
2. 2

   Step 2: Place background bitmap in top viewport for reference

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   Step 3: Create a new layer called "Handle"

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   Step 4: Select the "handle" layer and start tracing the handle outline using control point curves (turn off snap)

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   Step 5: Use the join command to join all the curves into a closed loop

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   Step 6: Make a copy of the closed curve and move this curve up a few mm in the Y direction

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   Step 7: repeat this again but this time move it down the same distance.

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   Step 8: Make another copy of the closed curve and move this up in the same way done in step 6

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   Step 9: this line will form a guide for the knife cavity

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    Step 10: so this distance will be considerably shorter.

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    Step 11: Select the top curve and turn on control points.

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    Step 12: Turn on End in the osnap bar and connect the top two curves with a line from this point

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    Step 13: repeat for the bottom half.

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    Step 14: Do the same for these parts at the front of the knife

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    Step 15: Now use control parts to drag together these two points (using end snap might make this easier)

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    Step 16: step 12- Take a small break

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    Step 17: drink some coffee

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    Step 18: have a nap...

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    Step 19: Now select all the curves and use the explode function

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    Step 20: We are now going to start making surfaces

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    Step 21: most can be done using EdgeSrf

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    Step 22: but others require a 2 rail sweep.

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    Step 23: Now make sure you join the following curves again to act as a rail for the sweep you are about to perform:

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    Step 24: Perform a 2 rail sweep with the previously joined curves as rails and the straight line between the layers as a cross section.

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    Step 25: Perform a similar sweep on the following curves:

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    Step 26: Draw a curve similar to the shown in the screenshot

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    Step 27: this curve should be at the height of the top handle curve.

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    Step 28: Now split the top handle curve using the curve you just added using the split command.

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    Step 29: Use the split curve and the drawn curve as rails for another 2 rail sweep

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    Step 30: Select the following collection of curves on the top surface of the handle (this might require you to explode some previously joined curves.

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    Step 31: Draw a circle where you want the pivot for the knife blade to be and use this circle to split the two surfaces you just created.

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    Step 32: Extrude the circles into the handle about halfway.

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    Step 33: Use PlanarSrf to make a surface closing the extrude you just made.

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    Step 34: Turn on center snap and draw another circle in the middle of your previous one.

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    Step 35: Extrude this circle to the bottom of your half handle shell.

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    Step 36: Create three new layers

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    Step 37: "handle top"

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    Step 38: "handle bottom" and "blade".

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    Step 39: Select layer "blade".

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    Step 40: Select the blade curve

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    Step 41: and copy it.

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    Step 42: Join the curve loop on the bottom and extrude it upwards to touch the top curves.

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    Step 43: Select the following curves copy them and move these upwards towards the top half of the handle.

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    Step 44: Turn on end snap and draw lines as illustrated below.

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    Step 45: Extrude the back curves to join the rest of the blade

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    Step 46: Use PlanarSrf to close the bottom of the blade.

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    Step 47: Switch to top view and draw a curve as illustrated below.

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    Step 48: Turn on control points and connect the end of the curve with the tip of the blade.

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    Step 49: Draw two diagonal lines from where the blade is extruded to the curve separating the blade.

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    Step 50: Close the triangles and the top back of the blade with PlanarSrf.

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    Step 51: Use a Sweep2 to close the first side of the blade

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    Step 52: repeat for the other side.

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    Step 53: Make a hole the same size as the holes in the handles in the top and bottom of the blade using split and deleting the circle surface.

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    Step 54: Select the whole blade and join it into a single polysurface.

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    Step 55: Select the bottom handle layer

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    Step 56: we are going to make a surface that will stop the knife blade from moving when folded open.

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    Step 57: Finish the knife cavity in the knife handle.

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    Step 58: Draw a curve that loosely follows the knife outline then join the curves

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    Step 59: Split the following curves using the knife outline:

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    Step 60: Join the curves into a closed loop and extrude this up to the top half of the knife handle.

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    Step 61: Use PlanarSrf to close the handle as shown.

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    Step 62: Final model!

Detailed Guide

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