Autodesk Inventor

[#1]

This must be an easy question, but it has haunted my for a while... I
searched old NG posts and Mymcad but didn't find any answers.

I have difficulty getting the extrude and revolve commands to recognize
profiles involving projected geometry. If the sketch has lines that extend
beyond the profile I am looking for, then IV rarely detects the profile. I
often have to resort to drawing additional lines on top of the projected
geometry(ugh!) to get the profile to be recognized.

I have put a small example of this in customer files. It is two disjointed
cylinders with a sketch located on a plane running through the axes. I
projected the top and bottom faces of both cylinder features, projected in
the center axes of both, and connected the ends of the projected top/bottom
faces with lines. I want a rectangular profile bounded by the top and
bottom of the cylinder features and their projected center axes. I have to
a) draw a line from the midpoints of each projected cylinder face on top of
the projected axes or b) change projected axes to normal, unassociated,
geometry and trim them before a profile will be recognized. That just
doesn't seem right. Is there a setting or trick I'm missing?

Thanks

--
Mark Case, P.E.
Sr. Mechanical Engineer
CaseCAD Engineering
(509) 773-7305
web: http://w3.gorge.net/casecad

[#2]

I run into the same problem......dunno what the solution is, but would really like to find one.

[#3]

Well ... since profiles have to be closed before they will extrude, the way
I usually do something like that is project the top of one cylinder and the
bottom of the other. Then project the axes'. Next use the rectangle tool to
make a rectangle and use the collinear constraint to constrain it to size.
~Larry

"Mark Case" wrote in message
news:50C771F6085E23060F1C3CDE8B3880CC@in.WebX.maYIadrTaRb...
> This must be an easy question, but it has haunted my for a while... I
> searched old NG posts and Mymcad but didn't find any answers.
>
> I have difficulty getting the extrude and revolve commands to recognize
> profiles involving projected geometry. If the sketch has lines that
extend
> beyond the profile I am looking for, then IV rarely detects the profile.
I
> often have to resort to drawing additional lines on top of the projected
> geometry(ugh!) to get the profile to be recognized.
>
> I have put a small example of this in customer files. It is two
disjointed
> cylinders with a sketch located on a plane running through the axes. I
> projected the top and bottom faces of both cylinder features, projected in
> the center axes of both, and connected the ends of the projected
top/bottom
> faces with lines. I want a rectangular profile bounded by the top and
> bottom of the cylinder features and their projected center axes. I have
to
> a) draw a line from the midpoints of each projected cylinder face on top
of
> the projected axes or b) change projected axes to normal, unassociated,
> geometry and trim them before a profile will be recognized. That just
> doesn't seem right. Is there a setting or trick I'm missing?
>
> Thanks
>
> --
> Mark Case, P.E.
> Sr. Mechanical Engineer
> CaseCAD Engineering
> (509) 773-7305
> web: http://w3.gorge.net/casecad
>
>

[#4]

Larry,

Thanks for the reply.

I usually do something like that too, but it turns out to be a lot of work
on a more complex sketch--my example was VERY simplified. I am expecting it
to work like, say, the bpoly/bhatch command and find the boundary for me.
The method you suggest(and I currently use) results a hodge podge of
overlapping geometry and constraints -and- is time consuming.

Mark

"Larry Caldwell" wrote in message
news:903AE6D74015F080C557B7C60B43FB72@in.WebX.maYIadrTaRb...
> Well ... since profiles have to be closed before they will extrude, the
way
> I usually do something like that is project the top of one cylinder and
the
> bottom of the other. Then project the axes'. Next use the rectangle tool
to
> make a rectangle and use the collinear constraint to constrain it to size.
> ~Larry

[#5]

It does overlap the lines but naturally they can be deleted as you know. If
it was one piece projecting the face is real quick but that's not always
bulletproof either. Don't know how one would go about making reference
geometry resize and constrain itself, though, since the idea of reference
geometry is to remain fixed.
~Larry

"Mark Case" wrote in message
news:5AE545C7D72D089FBC6FB72951086203@in.WebX.maYIadrTaRb...
> Larry,
>
> Thanks for the reply.
>
> I usually do something like that too, but it turns out to be a lot of work
> on a more complex sketch--my example was VERY simplified. I am expecting
it
> to work like, say, the bpoly/bhatch command and find the boundary for me.
> The method you suggest(and I currently use) results a hodge podge of
> overlapping geometry and constraints -and- is time consuming.
>
> Mark
>
> "Larry Caldwell" wrote in message
> news:903AE6D74015F080C557B7C60B43FB72@in.WebX.maYIadrTaRb...
> > Well ... since profiles have to be closed before they will extrude, the
> way
> > I usually do something like that is project the top of one cylinder and
> the
> > bottom of the other. Then project the axes'. Next use the rectangle tool
> to
> > make a rectangle and use the collinear constraint to constrain it to
size.
> > ~Larry
>
>
>
>

[#6]

Well Larry, it doesn't seem like I touched a nerve with this one. I was
hoping to get a better handle on what IV needs to detect a profile. If you
draw four overlapping lines(as for tic-tac-toe) it won't recognize the inner
square as a profile, but if you trim two of the lines so their endpoints are
on the longer lines it will?

I guess I won't beat this horse anymore, except to request an iPoly command
to make creating the extra geometry quicker...

Mark

"Larry Caldwell" wrote in message
news:632490CF72F542A584C920F709D27189@in.WebX.maYIadrTaRb...
> It does overlap the lines but naturally they can be deleted as you know.
If
> it was one piece projecting the face is real quick but that's not always
> bulletproof either. Don't know how one would go about making reference
> geometry resize and constrain itself, though, since the idea of reference
> geometry is to remain fixed.
> ~Larry
>

[#7]

Then you wouldn't be using projected reference lines anyway. So now you want
another command to draw the thing with? You can draw a rectangle and dim it
to the origin; can't see a reason for duplicating the rectangle/polygon
tools command with another redundant one, can you?
~Larry

"Mark Case" wrote in message
news:346388066BBB9A47C9D27FBD7A901B04@in.WebX.maYIadrTaRb...
> Well Larry, it doesn't seem like I touched a nerve with this one. I was
> hoping to get a better handle on what IV needs to detect a profile. If
you
> draw four overlapping lines(as for tic-tac-toe) it won't recognize the
inner
> square as a profile, but if you trim two of the lines so their endpoints
are
> on the longer lines it will?
>
> I guess I won't beat this horse anymore, except to request an iPoly
command
> to make creating the extra geometry quicker...
>
> Mark
>
> "Larry Caldwell" wrote in message
> news:632490CF72F542A584C920F709D27189@in.WebX.maYIadrTaRb...
> > It does overlap the lines but naturally they can be deleted as you know.
> If
> > it was one piece projecting the face is real quick but that's not always
> > bulletproof either. Don't know how one would go about making reference
> > geometry resize and constrain itself, though, since the idea of
reference
> > geometry is to remain fixed.
> > ~Larry
> >
>
>
>

[#8]

Larry,

Why, yes, I can see the need for the extrude/revolve command to be smarter
at detecting profiles, and/or for some faster way to create whatever
geometry is necessary for a valid profile. Obviously this would NOT be
required for a regular polygons, but for irregular polygons formed from the
projected edges of multiple features or parts. This is more important when
working with projected(associative) geometry because it cannot be altered to
create a 'valid' boundary.

I'd settle for an explanation of what extrude/revolve requires to detect a
closed profile. I just did a couple of tests and it fails to detect a
profile when all of the vertices are not coincident another member of the
group of geometry forming the boundary. Is that the requirement? The iPoly
feature/method would(like bPoly and bHatch) find a profile from ANY geometry
that forms a closed area.

Mark

"Larry Caldwell" wrote in message
news:F4F2465AA1BEB789CBB83AB76DA3E973@in.WebX.maYIadrTaRb...
> Then you wouldn't be using projected reference lines anyway. So now you
want
> another command to draw the thing with? You can draw a rectangle and dim
it
> to the origin; can't see a reason for duplicating the rectangle/polygon
> tools command with another redundant one, can you?
> ~Larry
>

[#9]

It does the same thing in Inventor if I understand what you are saying. If
you project a face it will give you a closed loop of that face and you can
extrude it from there without adding or subtracting anything (there are some
exceptions that I've seen mostly with splines, I think, that can whack
sometimes). A loop will also close on projected reference lines where the
end points aren't coincident if you have other (drawn) lines with coincident
constraints somewhere on the projected geometry. In that case (thinking of
our example) the geometry would only have two projected lines (end points
not coincident) and don't intersect the drawn lines except where the
coincident constraints are. A closed loop means just that: no breaks in the
profile and Sketch doctor will find them forthwith if they exist. A closed
loop is required to make a solid, but you can extrude a surface from an open
loop, depending on the technique you are using. If other geometry is needed
to honor the design intent then it can be added as needed. I routinely
ignore overlapping lines and haven't seen any problems with it. That was at
the root of my suggestion before about constraining the rectangle or
whatever shape to projected geometry. I use as many constraints as I
possibly can to minimize the number of dimensions required and I'm not sure
what the "iPoly" would do that can't already be done the way IV is set up at
present. Do I understand what you are saying correctly?
~Larry

"Mark Case" wrote in message
news:61B299B0B22CCF69732D57BEF7ED94A9@in.WebX.maYIadrTaRb...
> Larry,
>
> Why, yes, I can see the need for the extrude/revolve command to be
smarter
> at detecting profiles, and/or for some faster way to create whatever
> geometry is necessary for a valid profile. Obviously this would NOT be
> required for a regular polygons, but for irregular polygons formed from
the
> projected edges of multiple features or parts. This is more important
when
> working with projected(associative) geometry because it cannot be altered
to
> create a 'valid' boundary.
>
> I'd settle for an explanation of what extrude/revolve requires to detect a
> closed profile. I just did a couple of tests and it fails to detect a
> profile when all of the vertices are not coincident another member of the
> group of geometry forming the boundary. Is that the requirement? The
iPoly
> feature/method would(like bPoly and bHatch) find a profile from ANY
geometry
> that forms a closed area.
>
> Mark
>
> "Larry Caldwell" wrote in message
> news:F4F2465AA1BEB789CBB83AB76DA3E973@in.WebX.maYIadrTaRb...
> > Then you wouldn't be using projected reference lines anyway. So now you
> want
> > another command to draw the thing with? You can draw a rectangle and dim
> it
> > to the origin; can't see a reason for duplicating the rectangle/polygon
> > tools command with another redundant one, can you?
> > ~Larry
> >
>
>
>

[#10]

I may be misunderstanding all this myself, but ... I think what Mark may be
looking for is a equivalent of the vanilla "Boundry" command.

If you aren't familiar, put a clothespin on your nose and open AutoCAD.
Draw two overlapping circles and then type in -boundary and select in the
area shared by the two circles. Now type in Move and do a crossing window
of that area... you should have ahold of a shape the same as the shared
area.

In derived sketch modeling I could see the value in a tool like this.

Oh... yeah... wait 15 minutes and then remove the clothespin

--
Kent Keller
Member of the Autodesk Discussion Forum Moderator Program

http://www.MyMcad.com/KWiK/Mcad.htm

"Larry Caldwell" wrote in message I'm not sure
> what the "iPoly" would do that can't already be done the way IV is set up
at
> present. Do I understand what you are saying correctly?