Making a mold from imported .step

Rhino Rhino for Windows
1

LH STEP no holes 1 v6.step (10.4 MB)

Hello all! I have an imported surface model attached that I am trying to make a mold from that can be machined from a solid block. My aim with this model is to extend the edge loop by 20mm, and then create a further loop parallel to the ground plane, and to finally close the whole beneath of the model with a box that can then be the body of the mold.

So my first thought is to ‘extend surface’ but I can only complete this after exploding the part, and then can only extend 1 surface body per time… slow, painful, and doesn’t always work.

So to speed this up, I’d like to create a sketch or curve (I’m new to Rhino!) from the edge loop… is this possible? If so, can anyone help me find the tool to do it?

Or am I looking at this all wrong?

Effectively I am trying to do exactly what is shown in this video Mold Making Tools: new in Rhino 7 - YouTube except I only need the bottom part of the mold and it must follow the edge line where the surface is cut?

Any and all help is appreciated!

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I am trying to do the same thing in inventor, but find that some faces the direction seems to flip. But effectively I would like to recreate this from an edge loop, and then outwards at 90 degree, then down to create the block that we feature is machined into…

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If the cross sections of the 20 mm extension are to be somewhat parallel to the ground plane, you can follow steps shown in How to Make a Partition Surface in Rhino 3D - YouTube , but particular to your model:

  1. Do not explode the model.
  2. Set the viewport’s CPlane to be parallel with the ground plane. In this model, it may be _CPlane with option _World then _Back. (Words with underscores are commands and options, and are not needed in English language installs of Rhino.)
  3. _DupBorder to obtain the perimeter as a single polycurve.
  4. Follow the aforementioned video on how to use _RibbonOffset on the curve from #3.
2 Likes
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Thanks for this, I will give it a try later this evening. The 20mm extension needs to be simply a continuation of the already existing surface. Then an additional surface parallel to the ground plane, making a block similar to the video in the original post.

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Ok I’m a bit stuck still, I’ve managed to create the 20mm run off parallel to the cplane, but when he tells you to select the outer curve and scale to 0 giving a flat surface that is the body of the mould I can’t get it to work? He’s getting a flat projection of the perimiter line but I can’t make that happen and he doesn’t show what hes doing at this point? Can you help? Thanks!

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He is using the Gumball. Be sure that it is enabled in the status bar.

  1. He makes a copy of the curve, and with one of the 2 curves selected,
  2. He clicks the Gumball’s Scale Z control (blue square / #12 bubble on the help page) and a textbox control appears.
  3. He enters 0 in the textbox and presses Enter.