Modeling Diving Knife Tutorial

STEP 2 – BLADE

Ok, now we got our blueprints set up the way we want, and now we’re gonna speed things up a bit. Basically all you need to do is to trace the outlines of the blade. Use (or PolyLine) and Ortho for straight lines, use for curves, and to match the curves to other lines or curves to get smooth transition between them. Usually Tangency is enough option in command. For the little circular blades on top of the blade use two circles with various radii. And with just trim the lines you don’t need. 😉 It was easy to say it, but lets get on it and make it. And for your convenience you can put the into another layer and lock it. So when you move or select or perform any other action you don’t mess with the blueprints.

Basic lines & curves

Basic lines & curves

So, as you can see, in the picture above, there are just simple lines and curves. For the lines, make sure you use Ortho so they are straight, either vertically or horizontally. So, naturally next step would be to Trim some lines. You can hide the middle line, we don’t need it anymore. Ok, now we have some lines and some curves. To you they might seem to be ok, because I did make them pretty accurate. But not 100% accurate. we need our curves to be tangent to our lines. We can adjust that with Match command. Now, the important thing is to note that once you are in the Match command it asks you first for the line or curve that will be edited to match the Match settings (Position, Tangent or Curvature) and then for the curve that you will NOT change with Match command. Of course there is one option in Match command that lets you change both curves (Average Curves) but we’ll get to that when creating the handle.
Match positions

Match positions

Match settings

Match settings

Repeat this for other two.After matching all the curves to the lines, we will need to two lines:
split lines

split lines

Now, create a on the Mid point of the little line you created by splitting the top straight line. Once you create the line, move it up by units. This will be the center of .
point

point

Ok, now create a Circle with 10 units as radius and as center use the point.
circle

circle

Now, guess what, we are going to Trim that circle with the line and it using the line we recently hid to make the copy on the bottom side as well.
curves and lines for planar surface

curves and lines for planar surface

Before we go and create our first surface, we need to join the curves. Select all the lines and curves like on the image above, and them. Next thing we need to do just before creating surfaces is move the lines we just joined. From the blueprints we can see that the thickness of the blade is 5 units. Since we started everything from the origin (0,0) we already have set up mirror plane. We can just make one half, and then Mirror it to the other side as well.
Move by 2.5 units

by 2.5 units

Using Line command create one Line like on the image below, and using Copy command copy it 3 more times. Using End OSnap option will do the trick.
Four lines

Four lines

Create one more Line:
Another line

Another line

Do the same for bottom with Mirror or create a Line again. Now, using turn on the control points of the left horizontal curve. And move the last control point to the end of the inner tip of the flat closed set of lines and curves:
Points On

Points On

Now, from top viewport (it would be smart to disable OSnap for the moment) adjust other control points so the curve gets the smooth arched direction:
Adjust control points

Adjust control points

After you adjust the remaining control points, you can enable your OSnap now, and using command hide the control points. Now, go ahead and create your first surface. Using PlanarSrf command create a surface out of closed set of curves:
Planar surface

Planar surface

Using command explode the closed curve set you just used to create this planar surface. And, then using Join command join these curves only:
Two sets of joined curves

Two sets of joined curves

I’ve created this line with Line (or PolyLine) command starting from the top corner and moved it down to be perpendicular on the edge of surface (or curve). Use Perp in OSnap.
line

line

Ok, now with command we will use upper and lower sets of curves as rails (yellow), and three section curves as sections (red):
Sweep2

Sweep2

Now, lets set some curves for the lower part of the blade. First we need to Join 4 curves into 2 curves:
Two joined curves

Two joined curves

Again, using Sweep2 command, create a surface:
Sweep2 surface

Sweep2 surface

Now, using PlanarSrf we will fill in the two gaps we have left. Then we will extrude this set of two lines and one curve with command.
Extrude

Extrude

For the extrusion height you can type in 2.5 or just use any of the lines as reference points:
Extrusion

Extrusion

Do the same for the other side, or just Mirror it. Now, using command fill the side of the blade:
SrfPt

SrfPt

Ok, now Join every surface. Then Mirror that polysurface and Join those two halves. Now, we have our blade form on which we will proceed with modeling details.
Base blade surface

Base blade surface

Using Line command, create a line on top of the blade edge.
Line

Line

But try not to snap to the left end, but rather finish the line a bit closer to the corner:
Closeup

Closeup

Next thing we’ll do is the line into 7 parts. The command isn’t actually splitting the line into 7 separate parts, but it places Points on the line instead.
Divide

Divide

So, using the second point looking from the left we will Split this Line:
Split

Split

Ok, now we need our blueprints again. You can turn on the layer you put your PictureFrame in on. Using command, make sure you click on the StartPoint option in the command line, and then click on two points:
Click on Radius to input the radius

Click on Radius to input the radius

Now, like on the picture above, click on the Radius in the command line, and input number 6 as radius. After that click on the viewport (Front) to set the direction of this arc.
Arc

Arc

Make another Arc with 8 units as radius, and using Copy command copy those two arcs 6 more times:
Copy arcs

Copy arcs

Now, using the bigger ones (stay in this viewport – just set it to Ghosted by right clicking the Front caption) Trim the blade surface:
Trim surface

Trim surface with bigger arcs

Now, using command make a surface between two edges and one smaller arc:
Loft surface

Loft surface

Repeat this step for all other six arcs, or just Copy this surface six more times:
Final blades

Final blades

Next, just Join all surfaces. And for the last thing in this step we will use the same method on the bottom blade. So, first using blueprints, trace the outlines with command. Adjust the curves with PointsOn command if needed.
Some more curves

Some more curves

Before we start trimming the surface, we need to trim our smaller curve with the surface.
Trim or Split this Curve

Trim or Split this Curve

Now, using bigger curve we will trim the surface:
Trimmed surface

Trimmed surface

Now, adjust the smaller curve’s ends. With PointsOn command we will show the control points and move each end to the end of the surface:
Adjust curve

Adjust curve

After that we need to hide the control points with PointsOff command. Now, again, with Loft command make a surface: (it might be necessary to do one side at the time and then Join both)
Final step on the blade

Final step on the blade

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16 Responses to “Modeling Diving Knife Tutorial”

  1. Brian Lake says:

    AWESOME tutorial! Haven’t seen any other tutorials with this much detail!

  2. Ivan says:

    thanks Brian, I appreciate it 😉

  3. Keke says:

    Looks a lot like Ragde’s diving knife.

  4. Ivan says:

    It is. If it is “his” design.
    I’m not really teaching design here, rather just modeling in Rhino.

  5. Robert says:

    What dimensions do you use and what version of rhino is this?

  6. Ivan says:

    I used centimeters, but those measures aren’t absolutely accurate, just a reference. Rhino version is v4.0 for all tutorials on this site.

  7. brad says:

    is it possible to use background bitmap instead of pictureframe? for some reason pictureframe just draws a frame and there is no image. do you know why?

  8. Ivan says:

    sure is. you can use background bitmap. As for the image not showing in pictureframe, search the forum, there have been couple of similar questions. I’d guess it might be problem with drivers. But than again, I might be wrong.

  9. Dioniso says:

    Excelent tutorial. Thank you!

  10. Gianluca says:

    Great tutorial but i have some trouble with the first sweep 2 rail for handle. i get some strange surface result. may i send you an image by email to check what is the problem?
    thanks in advance

  11. Ivan says:

    go to http://www.rhino3dhelp.com/forum/index.php?board=11.0 and open a new thread with your image attached.

  12. gnob says:

    first of all thank you for this awesome tutorial..,, second is to cast a newbie question.. how can I view the image after I make a picture frame?? it seems no bitmap image or jpeg Appeared after the operation…pls…help… if I’m going to use background image it will appear ,but if I;m going to use picture frame it won’t appear. only a rectangular line appeared….. as this tutorial instructed is much easy to use picture frame than background image….. pls…help….Much appriciated your help and respect..

    regards

  13. DeigoIce says:

    Yo!
    Just finished the model, looks a bit diferent, but i’ve learnd a lot of tecnichs, and a lot of stuff by myself, thnx rhinoh3d!

  14. Mila says:

    I havnt had Rhino3D for that long and I dont know how to get the image of the diving knife into Rhino3D like in Step 1 pic 1 plea help

  15. Mila says:

    nvm found out how

  16. shnh says:

    Excelent tutorial .thank you (:

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