Failing to surface

Hi, im feeling really stupid here…
Im working on a knife handle and sheet model to be cnc’ed.

i made a scan, drew the lines around the knive, joined the lines, moved 2x 1.5mm,
Moved the lines representing the knife’s edge to the middle curve in Z. Lofted and perfect.

Knife profile is made.

But i can’t cap the blade, or edgesrf to make a top/bottom surface… I wouldn’t mind making a mesh to grind some test blades…

What am i doing wrong?

test.3dm (1.7 MB)

Hello @xavier.bury
I would try to make a single line for the sharp and the flat sides of the blade and make them around the same lenght

loft those lines then move all the points 1.5 mm up except the sharp edge ones, this should give you one side of the blade.

mirror that surface and loft remaining flat surfaces then cut the handle stuff.

kind regards,

Blade_Blastered.3dm (201 KB)

Thanks @Blastered !

Someone sent me a msg to try patch and it also worked. Then lofting the patches was perfect.
I tried with your 3dm file but couldn’t figure it out.

Still a draft but quite happy! Drafting handle in GH and the scabbard soon…

Hello - I’d be inclined to make it with a thicker edge and then ‘grind’ it sharp with a cutter, to get that separate cutting edge.

testKnife_Maybe3dm.3dm (1.9 MB)


Nice touch, would work for some Japanese tantos! However this blade (for a gyuto) is a near perfect triangle profile - bit rounded - not sure how to model that without lots of measuring yet.

I would make it like this:

In your file the curves are twisted and not planar, in the tip for example, they should touch and is not the case.

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ouch, i got sloppy. Thanks @DiegoKrause

I wanted to keep the side as a single surface, so I made it slightly differently:

  1. I copied your curves and reoriented them so the centre of the knife will fall on the XY axis plane and the curve at the rear of the blade itself is in the YZ plane. This makes life easier.
  2. I continued the curve at the rear of the blade with a straight line across the tang, then matched the curve to the new line to get curvature continuity.
  3. I split the curve defining the back of the blade where it intersected my new line.
  4. I extended the back and edge curves with straight lines beyond the end of the tang and made a scaled-up copy of the rear curves there.

  1. I then swept that curve to the tip chaining the back and edge curves as rails to create a surface.

  2. I trimmed the surface with the curves outlining the tang.

  3. I then offset the edge curve a few millimetres on the surface, then offset the edge curve again, by one millimetre inwards on the xy-plane, Then trimmed the ends of my offsets to the knife outline, followed by trimming the surface back to its offset.

  4. I connected the adjacent ends of my two offsets with lines and swept them using the offsets as rails to give the knife a honed bevel edge surface.

  5. I mirrored the large surface and the bevel to create the other side, then created the surface forming the back of the knife, around the tang and down the rear of the blade.

  6. To finish I booleaned out my mark in the tang, created a handle and ferrule, applied materials and placed my objects in a simple scene to give:


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Thanks for the detailed explanation and the amazing render!

How do you guys get such good wood graphics???

That’s superb! Even Stamped engraved the knife! (Still a small detail i need to polish in my designs)! Nice details, i have so much to learn!

Is that rendered with VRay? Im still on the basic rhino package rendering and learning my way through (was only using cycles render before until i saw the “render” button in the panel 2 weeks ago (after 8 months!)! The joys of self-learning and finding new better things! Took me a few hours to learn how to map the blade scan on the blade - but getting the hang of it.

I got lost doing a better handle (stupid problem so left for later), but learned to render better.

Is there any way to map textures in GH? I found the “create material”, but not a texture mapping…

Thanks again!

No, that is rendered with Cycles (setting the viewport to Raytraced and using the Capture to File option to get a .jpg output). Cycles is the way rendering is going in Rhino 7.

The wood is Japanese Elm from the Rhino materials library. In case you haven’t come across it, here is a really good tutorial that helps turn materials in Rhino from a frustrating “mind of its own” nightmare into an obedient servant: Materials and texture mapping in Rhino 6 for Windows on Vimeo

The blade material, incidentally, was adapted from another wood using Photoshop as I couldn’t find any tamahagane or damascene steel materials.


Thanks Jeremy. Are you a knife maker?

No, not something I’ve tried yet, but I admire the craftsmanship.

Somehow i came here because i decided to get into Japanese woodworking 5 years ago because of their steel. Because of laminated wood designs for gun scales (i hate guns), because of a cnc, and because i finally found a 3d program i can draw naturally with! Grasshopper was the way for me to model layered wood/steel over other shapes i wanted!

if you want some textures of tamahagane or damascene steel check out:

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