This site is amazing with its info and help. I'll get that rotary sucker
 running yet.


 --
 Karibian

 Paul, on the subject of HELP !!!! I could really use some. I am trying to
redraw my rotaty engine parts using Rhino. I have read the book but still
can't generate a tapered solid. I am using a closed (joined) line made of
arcs and straight lines. All the direction vectors point the same
direction.
Extruding the "curve" with a 3 degree taper usually results in only part of
the line being extruded. In a few cases the whole line did extrude but it
was segmented not continuous. Joining the extruded polysurfaces made the
polysurface continuous, however, they would not cap into solids. The
message
is "unable to cap that object" I have  tried a thin straight extrusion to
make a surface and doing a solid extrusion of that.Still a partial
extrusion
or an uncapable surface. I have converted the curve to line segments, this
extrudes with a huge file size but still doesn't cap into a solid. I have
devided up the curves into smaller parts and tried that, still no joy. I
have redrawn the parts with a simplified shape (larger radius arcs) and
fewer lines and arcs with no improvement.  My only success was the
bellhousing which works if taper is in and direction is negative. This
curve
fails to extrude if taper is out. All the "curves" were drawn in Rhino
which
is a fully functional (for 1 year) student version. If I do straight sided
extrusions everything extrudes and caps into a solids, however that does no
good for foundary patterns which need to have draft. I keep thinking I have
to do something to the lines to prepare them for the extrusion since there
are no options on the extrusion command that help the situation.Any help
anyone an give me would really be appreciated.

george grimes

Hint. Use loft instead of extrude.
Draw 2 circles of different diameters in the front view. Drag one
away from  the other in the right view. Go into the perspective view
and choose loft. Select the first circle and then the second and press
loft.
The best results happen when you get the little arrows lined up
in the front view. If you have 3 circles of different diameters
you can get a bell housing shape.

Paul Lamar


Paul, Thanks a lot IT WORKS!. Except for small parts which turn in on
themselves and have the sections widely spaced which make hourglass shapes ?
I also tried the edgesurf command with the two sections (one offset for the
taper) which is often successful. I put surfaces on the top and bottom with
"planarsrf" , then flip any vectors which are pointing in , then glue the
pieces together with the join command. Some early tests of the boolian
commands indicate the result must be considered a solid. I discovered
accidentally while using the offset command to make the smaller section for
the other end of the taper that some sections could not complete the closed
curves. A side view of the curves looks to be in the same plane, but the
global tolerence setting is .0001 which doesn't allow much carelessness.
This is a test that will predict the failure and show where the problem is.
            I think this is due to not moving the construction plane and
some snaps going to a different elevation. Now I draw a line then snap to
the section and drag it to an end snap on the  drawn line to change the
elevation to the construction plane. This has been bulletproof so far. I
just have to remember to do it.
    Rhino IMHO is just as fast as Autocad 14 as far as drawing is
concerned. Also being able to drag the drawing windows larger and smaller
with just the mouse is really nice. I was used to just extruding a regeon
into a solid in one step with Autocad so  drawing all the surfaces and
assembly work will take getting used  to.
        I had a thought today about RX7 dowel pin loading. It appears that
I could drill and ream an assembled engine on several tension bolt holes and
add more hollow dowell pins around them to spread the load. There is already
generous clearance around the tension bolts so not as much metal would need
drilled and reamed as it might seem. Such a long drill bit would only follow
the existing holes so replacing a housing later on would make refitting an
extra hole difficult.

george grimes

It takes a long time to get a feel for what Rhino loft
is going to do on complex shapes.

Paul Lamar