Hi xrok1, it looks like you might have this as a physical foam model prototype right now?

You may be better off using Rhino + Microscribe to trace some curves with points digitized directly off of your foam model. That's a kind of a reverse-engineering type workflow that MoI is not really focused on.

To get something sculptured like that you're going to have to build a curve scaffolding that has some of the major contours of the shapes in it, and use some of the more free-form type surfacing tools like Sweep or Network to construct a sculptured surface.

When you use Extrude, the surface that is created is totally straight in one direction. The final shape that you are trying to achieve here just does not have any kind of "straight-ness" quality about it at all - so Extrude + cutting the extrude just won't be suitable for this shape.


I'll see if I can make a quick attempt at it to show you how to get started. It will take a fair amount of work to position the curve framework that will be necessary to accurately create this shape though - many of the curves in your framework will not be flat 2D curves, they will be curves that swoop around in 3D - that's why it is easier if you could digitize the curves directly off of your model instead.

- Michael

thanks for your reply. unfortunatly i don't have access to a digitizer i'm sure that would be the best solution. but here i am trying to model a complex shape and pulling my hair out.

if this is achievable with MOI it would be a testament to good design software.

Hi xrok1 - to tell you the truth I would recommend using some other software for creating this shape, specifically I think a subdivision surface style modeler would be a better choice because it seems like you have very sculptured style model there. Your form is not driven so directly off of just simple profiles which is the easier thing to do in MoI.

It is possible to create that shape in MoI, but it will be quite a lot of work and it will be a lot more difficult to control subtle details of the shape.

Subdivision surface modelers are much more oriented towards sculpting type methods, by which I mean editing points in 3D space instead of in a more 2D profile driven way.

That's also why a digitizing arm would also help a lot since it would be easier to create a lot of traced 3D curves with it, which instead you will have to do in a much more painstakingly manual manner by adjusting every single point to a spot that you have to judge. This is difficult to do.

It's even difficult to easily describe the kind of steps that you would go through since a large amount of it is little subtle fiddling with point placement, like dragging points up a tiny bit, over a tiny bit, down in z tiny bit, adjusting some more, etc.., etc.., etc...

Anyway, here is about the best that I can do to describe it without spending days working on it...

To start with, I placed your bitmaps in the top and side view, and traced a curve in the top view over a part of the grip, placing control points at fairly regular intervals:



Then I turned points on, and switched to the side view, and dragged points up to make a profile that matched the upper part of the grip in that view - here you can see that in progress, each point is dragged straight up in the z direction until the curve is following that upper shape:



I then made a copy of those 2 curves (with ctrl+drag), slid the copies downward:



Then I started doing the same kind of point dragging but this time downwards:





I duplicated those bottom curves inwards and then did quite a bit of additional point manipulations, sometimes stretching the ends of the curves outwards and adding new points in with Edit/Add pt. After a bunch of little adjustments to different points, I ended up with this curve framework:



Then I decided to Loft through these, turning on the Closed option, to generate this surface:



It's certainly not a perfect result as-is - it might take quite a few more hours or maybe even days worth of tweaking and adjusting points, and possibly creating additional profiles before you could really get it nailed down. You also have to kind of have a feel for how the surface is going to behave when it is generated through these curves.

But that's kind of the process that you would go through to create a sculptured type surface that's not so blocky and more of a curving 3D shape.


Those curves and surface are attached here as grip.zip .


A subdivision surface style modeler is built more to work with surfaces like these, in that kind of software you will work more directly on the surface and they have tools that are very much more oriented towards adjusting points of the surface around in 3D space more so than MoI.

This just is not the kind of "simple model done quickly and easily" type of thing that is really the main focus of MoI version 1.0 .

- Michael

thanks again Micheal,

i don't think this is due to any limitations in MOI, trust me i've tried to model this prototype in many other CAD apps, ones costing thousands (SW) handled the problem less elegantly with even more frustrating results. i'm going to try again in the direction you pointed to see what results i can get that way.

BTW, did you have to create the profiles in any specific order to get the loft to work properly? Oh and is there any way to pause the rebuilding function while one is massaging the points?

Hi xrok1, yes it will definitely be a pretty big project in any system.

Some solid modeling systems like SolidWorks are really really focused on doing everything driven by 2D profile curves only - I'm not sure that they even make it possible to drag individual points of a sketch curve up to different levels in Z to create a 3D swooping curve like you can in MoI or Rhino.

So I think that MoI is likely to be a step forward from a very Mechanical CAD type program for doing this design.

But really once you are looking at a more sculpting type of procedure where you may want to make surfaces with subtle adjustments in them with some regions that kind of "bump" in or out, then that is really when the tools in a subdivision surface modeler do a better job - it is the type of thing that they are really focused on doing. MoI is just not as focused on this type of thing at this time.

If you do want to pursue it more in MoI, then another possible direction would be to model a base surface of the grip without the finger grooves in it, and then try to place the grooves in as separate parts later on, that may make it easier to create the basic form of the grip.

It's going to be a lot of work though...

- Michael

> BTW, did you have to create the profiles in any specific order to get the loft to work properly?

This one should work fine if you just window select all the curves and then do Loft. If you do pick them by clicking on them one by one, then you will need to click on them in the proper cyclical order because Loft will take them in their picked order when you select them by individual clicks.


> Oh and is there any way to pause the rebuilding function while one is massaging the points?

Nope, sorry.. What I would do for something complex like this would be to delete the Loft, then make several adjustments to the curves, and then create a new Loft after that.


With a sub-d modeler you will work directly on the surface itself instead of on guide curves that produce a surface later, that's one of the things that makes it easier for subtle 3D adjustments.

- Michael

It is possible to model something like this in MOI. I took a quick and dirty 10 min crack at it because its late/early here. Blocked out the shape in rough with a 3 spline vertical loft. Then used a "through points" spline with snapping to draw rounded spline profiles around the blocked out solid. Think of it like threading short loops of string around something (wrap some string around your forearm and you'll get the idea). Too late to write it up in full. I'll be back later to explain it more fully.

that looks pretty good, but a more detailed description would help. i don't understand what "3 spline vertical loft" means.

It means creating three horizontal profiles to rough out the shape as a solid. Top. Bottom. Middle. Loft them. Now you can use this with snapping and a "through points" spline to draw rounded loops around the solid. Those loops are spline crossections along the model that you can use to loft a new solid. Because "through points" uses Bezier rounding, you don't get the initial flat shape but something more rounded and organic looking.

Here's the file. It seems I lost the middle spline somewhere but it was there originally to snap the loop spline points onto the profile splines.