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# Style & Surfaces.. HELP!!!

#### james.lynch

##### New member
Everybody! I have a problem..

I have extruded (separately) 2 circular surfaces, I then wanted to build a complex (not as in difficult, but the curvature varies in x,y&z)surface to join those surfaces

View attachment 834

now I have no problem with the curve creation, but here is the problem! I created the curves by projecting them onto the surface from an original planar curve on a plane mid distance in between the 2 cylinders, but for some reason whenextruding the initial cylinder(from a circular sketch) it effectively halves the complete surface into 2 semi-circularsurface's.. (see the highlighted edges above)

now the problem arises when I project or drop the curves on towhat are effectively TWO surfaces so it splits theprojected curve in to TWO curves! which kinda messes up the creation of the surface due to the fact that it becomes a 5 sided surface, not a 4..

now I know the workaround of simply creating a few more curves and patching it up, which I have no problem doing BUT why should I have to!

I also was thinking of instead of projecting the 2 curves on to the surface I could create them on a plane inside the cylinder then just trim it. but again I dont want to ..

Surely there must be a proper workaround!

James
Edited by: james.lynch

pro cant create a complete cylinder.

create the half of the cylinder that you want to project onto then either mirror it later or create the other half in another feature.

miked

Miked,

why is this? is the limit 180 degrees? or could I create say a 350degree arc and extrude this?

Thanks,

James

the limit is 180 degrees, Iam not surewhy but it has been that way for as long as I can remember. I have complained about it before but I dont recall what the reason is.

miked

that's a bit ridiculous all right!maybe it a mathematical thing? there are easy enough workarounds, but I had a couple of angles there defined in a Layout which would change where the projected curve would hit the surface(s) and I was hoping to be able to change these in the layout and it would all update nicely..

guess that's impossible now.. unless you have any suggestions?

James

It was explained to me years ago from PTC that the reason for the 2 halves was for model referencing. i.e. if you wanted to create a datum axis through a point on the arc of the cylinder you wouldn't have to create a point first, again it's been a long time.

I personally think it's bunkand that its probably some thing linked towards Unix,but I got to say it has helped me more than hindered me in doing advanced modeling and cutting down on features.

Surely that can't be the reason! or at least if it was they could have put in a check box or something to say "make surface as two halves" or something like that..

I agree that it is sometimes helpful, but surly one should have the choice, at the end of the day it's not that hard to create a cylinder in two halves if you actually want them, but it seems that it is impossible to create it as one!

where is the logic?

James

James, sorry, I don't have an answer for you. But I'm curious to
know your workaround. I've found myself in similar situations
with a tangent curve chain that is actually comprised of separate curve
features. I tried the "Copy Curve" command but it seemed like the
copied curve was a little off the parent curves and my subsequent
surfaces wouldn't merge.

its a pain in the butt some times maybe this thread should be moved
to the "wish list" along with a wish that someone in ptc that can do

Big Joe,

I had tried the "Copy Curve" feature before all right, but like yourself didn't have much luck with it either!

My"workaround"I suppose really isn't a workaround, as in it still won't work in all situation - if I redefine the angle at which my style feature intersects the cylindrical surface, it will only work for some situations..

all that I did was create 1 extra curve and make the surface in two steps..

View attachment 835

But again this is quite limiting and if anybody know a better workaround, please let me know

Puppet, how do I move it to the Wish List forum? Or will I simply repost a similar post anddescription?

Thanks,

James
Edited by: james.lynch

James,

I would try one of these:

1-Rotate your cylindrical surfaces upon creation 90 degree so you have full 180 degree sides on the side of bridge surface or

2-Create a composite approximate curve from the projected curve.If the surfaces wont merge after extend the bridge surface

or you don't even have to rotate the cylindrical surfaces just reorient the sketch so that 180 split is in the place you need

Pedja,

Rotating the surfaces (or sketch) would not work in this case. I have a similar style feature to create on the opposite side (but not at 180 degrees to it)

View attachment 837

What I am trying to create is a top level bounding skeletonsurface for a finger (and eventual hand), I have been using some simplified geometry until now.

I have all the parameters such as bone lengths, mating angles etc set up in a layout and I was hoping that any and all changes made in the layout wouldupdate in the model tree.. but now, if I change the angle that it intersects at, it would change the curve definitions within the style features and probably cause the feature to fail..

as for merging the surfaces, I wasn' thinking of merging them all, only the various style features for each part of the finger, not to the cylinders..isit important to merge them all? I was hoping I wouldn't have to use the composite curve approach...

Also, I have a few questions about referencing with skeletal models, would you mind if Isent you a pm about it?

James

My idea is to rotate each cylindrical surface separatelyaround their own axes,you have 3 of them and each can be adjusted that both curves are in 180 degree half.<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />

As for rotation if you create a composite approximate curve after projection I don

Just forgot one thing.<?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />

If the angle between 1st and 2nd or 2nd and 3rd bone is too big and you cannot have both curves not falling into split at the same time use two cylindrical surfaces and rotate them separatly

Pedja, thanks for the help..

which method would you think would createthe more robust model? I'd really like to create a very robust model, I suppose that should be the idea all of the time..
, but hey, I'm still learning!

Thanks,

James

James, <?:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />

I would not build the motion flexibility into curve and surface creation.

Create an initial model as you have it right now and than rotate finger surfaces themselves. You have 3 joints and 3 surfaces. Rotating them around the cylinder axes will give you any angle position that you want and it will work 10 out 10 times