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approaches to modeling this part?

2

2ms1

New member
I've got a bit of an unusual "part" to model here. I'm modeling the most dital phalanges(finger bone) that makes up the fingertips of a hand (the tip-most bone segment).


I was curious what approaches others here might naturally pursue. I'm having a tough time deciding what strategy to take. Maybe a swept blend for most of the length of bone starting with the end at joint and terminating within the "fingerpad"/horseshoe piece which would be made separately and then merged and/or surface blended? Or maybe the use of a variable section sweepin there would capture the shape of bone with higher fidelity? Those are just two basic ideas I have right now but I feel there're many other approaches that I could be considering.


Opinions would be appreciated. I'm completely open-minded to any approach no matter how radically different from basic thought I listed above.


Here are some illustrations that show this fingertip bone from various angles:


View attachment 4087








The underside:


View attachment 4088








View from top:


View attachment 4089





View attachment 4090
Edited by: 2ms1
 
you can use style ( ISDX ) feature to create these complex surfaces ...

Havent used Boundry Blend but that is another option


Edited by: mahtab_msa
 
I am sure that Boundary blends will do the job on this just as well as ISDX, it depends on what you are familiar with and what you have available to you. In anoher job I have modelled femoral and tibial bones, also the upper and lower arms.


The method I used was boudary blending. I got hold of some MRI scans of the bones and started from there. Brought them in from IGES files and used those curves as guides for the boudary blends.
 
i too think that boundary blend will work cool in this kind of job
smiley2.gif
 
Ok here's the hitch: I need to be able to take this one model and use relations/inputs to relations to change the dimensions like length of bone, width at each end, height at each end, narrowness of skinny section, etc.


I need to be able to do these thing while retaining the same shape otherwise. The idea is that human fingertip boneshave a certain form, but they come in all different sizes (4' 9" big-boned woman with stubby fingers, 7' basketballplayer with gangly fingers, etc), and I want this model tobe readily resizeable in accomodation of this fact.


So, in other words, lets say I made one twice as long, well I would wantthings like, for example, certaincurvatures to stay the same despite length change, so all the splines would have to be spread out, not just one. Is it clear what I mean? Might this requirement make using splines followed by boundary blends much more difficult than say a swept blend with relations for each cross section?


I guess I'm wondering what people's experiences have been with using relations to drivedimensions on parts made with curves/boundary blends. Is it a good combination?
Edited by: 2ms1
 
I'm trying the approach shown below of combining a swept blend with a surface extrusion to form the basis of the "fingerpad" part. I plan to use a curved surface to trip off/shape the top side of the part to get a consistent rounded shape that goes all the way to the tip...


Anyway, I have an immediate, basic question b/c I'm really a beginner and do not know some of these basic things:


How can I make the piece of the swept blend that is sticking out past the fingerpad (pacman shaped extrusion) go away? I do not know how to get rid of this extra material.





View attachment 4103
Edited by: 2ms1
 
2ms1


Are you doing this in surfacing, or solids?


For solids, create pacman first.


then copy outside surface


create swept blend


use surface copy to cut away the excess material


In surfacing the order of the features doesn't matter, and you can do a merge of the blend with the copy.


HTH


Sip
 
Hey All :)


2ms1, I guess it depends on how accurate the part needs to be visually. I agree that Boundary blend would be good, but you could probably get quite close using standard extrudes,cuts revolves etc.


If you are truely are a beginner to pro-e, then you picked a challenging topic to start modelling, good luck
smiley2.gif
 
sip, or anyone else who knows, how do I do this kind of cut that you mention using surface copy? I have never done anything like this before.


Right now they are both surfaces, but I am happy to convert something to solid if that is necessary, as long as I would be able to still do boundary blends afterwards (either directly or by converting back to surface).


I do not know how to do this cut though. When I do merge, there is no choice of which parts to leave behind as merged that leaves what I want.
Edited by: 2ms1
 
Use Laser Scanning or Find a Med School or Hospital and use one of those devices that can show brain in Cross Sectional slices.

Edited by: mjcole_ptc
 
I wasn't able to get laser scanner. The idea of getting cross sections is intriguing idea, however it's doubtful that I could have gotten them for everything in a full hand. I'm actually modeling a full hand and all its bones. I've got just about everything else mostly with just really complicated swept blends and the joints are comprised of mechanical joints (as in machine parts - hinges) that are integrated with ends of bones.


At this point I have to remain consistent with this approach of doing it by eye and measurements with calipers of this duplicate of a real human hand that I got from med school.


I'm happy with things overall, but I could really use some advice, along the lines lines of possibilities I described in original postson this fingertip part.
 
2ms1, Its an interesting model so keep us updated with pics etc. I would love to help if possible.


When using surfaces, you combine the seperate surfaces using merge tool, merge should then provide you with 2 arrows which determine the areas to be removed / kept. Clicking the arrows will reverse the choices etc.


I am quite new to surfacing too, I am creating a specific shape of a window handle for a customer, there are many compounding radii etc similar to your parts but I am learning that the merge and trim tools are very useful, however they do take quite a lot of working out sometimes. I am also starting to make use of the Intersect command with sketches/curves, very handy for boundary blends on difficult shapes.


Hope your progressing well.
smiley32.gif
 
Cool Skint, glad you're interested in this. I had migraines over the VSS, but finallygotone to work with some help from another thread. Now the problem is the lovely new VSS surface will not merge with the rest of the part
smiley7.gif



Shown below is what I have now. I would like thenew surfaceto shave off everything shown sticking out above it and become the new top of the part. Problem is, no matter which way the arrow's pointing, thefeatures will not merge.


Anyone got any ideas on this latest issue? This thing'll be about the last thing I do with this part other than a few round and fillets. The swept blend (main body of part) and the "pacman" have been succeesfully merged into one, so it's a matter of just getting this surface to VSS merge:


View attachment 4152
Edited by: 2ms1
 
you might undo the previous merge of the sweep blend and change order of the merge.. say merge the vss & sweep blend then merge the pacman to it..


might also do a intersect of the surfaces to see if you get clean datum curves...
 
wish I had the file... can't read WF3sv..only WF2 or r2001 sv's


even with the pics it hard to see things ...old man eyes
smiley19.gif



can you iges it and post.. or PM and I'll give you a real email address
 
depending on what the use of this model is for... learning or for bone graft... to what acuracy you want etc. I would build a tutorial for you. You really should come in for training if you want to make this type of modeling your passion. Ill save you years of farting around in the wrong direction. Anyway....


Ill post something before friday.ie. Ill try to put an html tutorial together for just one bone by friday.


P.S. in buffalo this whole week. boring
Edited by: design-engine
 
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