Making changes to a Model

I don’t want to appear to be a pest, and I DO try to find answers to my questions before I come to this Forum, but I am evaluating Rhino6 as a Mechanical Design Tool and I am still looking for some basic functionality I need. Please bear with me. :no_mouth:

Consider this model
200712 Etched Box Unlike some of my esteemed colleague I do not always get things right first time :worried: so I would like to know if I can change things. For example, “How can I adjust the dimensions of the cube?” Further, “Can I adjust the dimensions of the cube without changing the dimensions or relative position of the inset triangle?”

I know I can use Gumball to scale the whole model in any orthographic direction but I would like to make specific dimensional changes. In real life I might have a bush through which a shaft must slide and I need to increase the diameter of the hole by 0.075 mm (that’s about three thou in the old money). I’d like to be able to do that without creating an entire new bush.

Etched Cube.3dm (75.2 KB)

@Vagulus Do you have experience with other CAD software? Have you worked through any of the Rhino tutorials such as the User’s Guide, Level 1 Manual and Level 2 Manual? Or are you assuming that experience with other CAD software should let you jump in and start using Rhino immediately?

Rhino does not have parametric capabilities like some other CAD software. It does have History which if used will update some geometry when input geometry is modified. Grasshopper is a visual system for creating geomety with explicit controls.

Hi Vagulus, '‘SolidPtOn’ is a good way to adjust solids accurately.

The bush example is a bit more tricky - cleanest may be to redraw the bush.
Use ‘DupFaceBorder’ or ‘DupEdge’ on the bush end and adjust/offset the resulting curves.
If the bush od has changed. ‘untrim’ the opening in the surface face and retrim/split/boolean with the new bush

Normally rhino is used for accurate freeform surfaces. The top of shapes that a mechanical modeler does not do well.

What type of objects are you planning on designing? Plane? Engine? Clock mechanics?

Here is thread to see what rhino can be used for: Real life product design examples made in Rhino

I have considerable experience (by no means expert) in Solidworks and Inventor, and I have looked at DesignSpark and SpaceClaim prior to discovering Rhino and ‘No!’ I do not expect to jump in (as you put it). I realize that Rhino operates in a different paradigm to Inventor and it it that paradigm I am seeking to understand.

I have a collection of video tutorials entitled Rhino 6 Lesson 1 … 30 (there are two lesson 30s). My impression of them is that they are directed to an audience primarily concerned with architectural design. There’s nothing wrong with that (we all have to live somewhere :wink:) but the primary functionalities required differ from those required for Mechanical Design.

I also have the User’s Guide.

In all, that’s a vast amount of information which is no surprise since Rhino6 has a vast range of functionalities. I won’t get familiar with it all in a couple of weeks (perhaps a couple of lifetimes). I am happy to work at that but I don’t want to spend a few weeks study only to find that Rhino6 can not, in the end, be what I need.

That’s why I come here and ask questions. :slightly_smiling_face:

How did you do THAT!!
I found SolidPtOn (I can’t find a SolidPtOff) but how did you select an entire face?

The ‘bush thing’ is, as you say, ‘a bit more tricky’ so I’ll leave that for now and get back to it later if I need to.


Thanks, scottd

‘PointsOff’ turns off control points and solid points - just pick, shift-pick or window select the points to adjust - ortho on in this case (match CPlane to move direction), play around with it… becomes second nature.

This is a video about solidtools:

For what it’s worth, I’ve yet to be unable to model an object in the mechanical/marine field and create drawings for manufacture using Rhino.

That’s encouraging :grin:

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That’s great. I’ll try to find the rest of that set too!

Hi - in addition to what has been said, also look into sub-object selection. That allows you to modify (move, scale, rotate) single surfaces of a polysurface.


I’ll do that too.

Sorry, Brian, but I have to ask, “How often do you model mechanical objects?”

I am not being frivolous, it’s just that just that being accustomed to a parametric modelling system I am having a bit of trouble tweaking an existing model. It’s all very well being able to change the shape of something but in Mechanical Design I need to be able to specify the magnitude of the change.

In a reactive sense I have discovered that dimensions reveal extensions - see dragging the corner of the cube

I call that reactive because I make the change to the object and the dimension reacts. However, By setting the Grid to ten microns

I can adjust a length within that tolerance (which is fine for 3D Printing :slightly_smiling_face:). That’s a bit finnicky, of course.

Am I right in thinking that there is no proactive way to do this in Rhino6 - that is, no way to simply change the dimension and have the model react to the change.

Correct. It is not the way rhino works.

Rhino is not a parametric modeler. Rhino is not the tool for you if you need/want a parametric modeler.

What is? You’re right, a parametric modeller would be the go. My problem is finding a free one that’s not a toy. Can you help?

Grasshopper is a free plugin that comes with Rhino. You can access it via the command _Grasshopper and it uses visual scripting for calculations.

Which ones have you rejected on that basis so far?