Paul,

Thanks for the advise with Rhino.  I was able to get most of the motor
motor frame modelled to within several millimeter of accuracy.  Length,
the important measurement is spot on.

I enter X,Y, and or Z coordinate for most of the work but I can't seem
to get it to work for the final 3/4  (19mm) pipes angling upwards and
outwards from the rear junction to the front face.
I need to draw in the lower cross bracing as well.

Now stumped.   I've accurately set points (checking the three views to
tweak and verify their position but when I try to run a regular line
between them, the line goes in a completely wrong direction.  On the
first set of angle pipes it worked but not on the opposite side.  I
mirrowed them and dragged  them into position.   Everything you see is
Boolean connected now.

Is there any way to select (highlight) the desired two points and then
command a line to go between them?

Attached is a JPEG of how far its come.

Oh yea I am using Version 4 for the Mac and being a trial program it is
buggy.  No one has reported this bug yet.

Doug in Japan

That is looking pretty good Doug. You need to triangulate those
first couple of bays.

You can choose two points out of plane in the perspective
view and snap a line between them.

Paul Lamar


Thanks Paul,


I tried that as well and it didn't work.  The first point is easy to
pick up because I highlight it first.  The second point has to hunted
for but usually the line is going now where near where I expect it to
go. Bug?

Diagonals: Yes you are correct.  The top one is in as you can see but I
can't get the lower one in yet either. The lower diagonal tube goes the
opposite way and has additional cross support 1/3rd along its length.
This causes the motor mount to  purposely fail to one side.   Saves the
occupants from having the engine on their heads.   In the five or so
major crash landings that have totalled Seawinds the engine mount has
performed its duty well.

The first accident straight into an rocky embankment on approach with the
prop going into beta mode caused an estimated 19g forward deceleration.
The mount held undamaged and the two pilots limped away and the plane
was rebuilt and is still flying today and you can see it at Oshkosh
every year.

Back to drawing.  I know I can weld a frame up faster but knowing Rhino
is a skill that will come in handy.  At least that is what I keep
telling myself:)

Doug in Japan


The sequence is:
place 2 points in top, side or front views.

Now here is the real 3D trick:
If necessary place both points in the same view
and go to another view to move it where you need it
in 3D with snap and ortho "on."

Now go into Perspective. Find the points.

choose curve>line>single line>tools>object snap> point

that gets the first one then

tools>object snap>point

and you are done.

The line will move around as you search for the point which is a bit
disconcerting but you will get used to that.


Erase the points when you are done to keep down confusion :)

Paul Lamar



Doug, The trick to drawing most anything is uing the snap settings. There
are small boxes to check on the lower part of the screen with captions wth
endpoint, near, center, perpendicularand intersection being the most
usefull. If you have points located to connect a line use snap to point.You
might check the snap "spacing" it is set in pixels of the screen. Set it
near the lower limit.If you first draw just lines   to all the
intersections  then use snap to endpoint of line and intersection snaps to
draw diagonals.

With lines you can measure all the angles at all the
intersections and length of the center of the tube.  Another useful data
entry is relative coordinates.. Start a line usually from an endpoint of a
line snap. Then when prompted for "to" type an r followed by the coordinates
measured from the place where you started the line. For instance, if you
want a line perpendicular to one of the planes start it with a snap then r
0,0,10 to make a line in the z direction or  r 10,0,0 to run it in the x
direction.

If your lines seem to be going in directions with a mind of their
own turn off ortho on the lower right of the display. This forces lines to
go in the directions of the axis and all 90 degree corners. The "snap
to",  functions override ortho if there is something to snap to, otherwise
you get lines parallel to an axis. You need to use 4 viewports (flyout off
top toolbar) with top, front, right, and perspective views. Just drag the
window frame edges around for the biggest view where you are working You can
snap points in any window during a command.

      after you have a line frame you can make them tubes by drawing a
"circle around" selecting one of the lines. Then extrude it along the line
(curve) to an end intersection. Then " extend surface" it to the opposite
intersection. The things related to lines are in the curves toolbar, things
for surfaces are in the surfaces toolbar. There are additional commands off
the bottom of the flyouts, just click the arrows..

    Once you have tubes or "pipe command" surfaces  you use the intersect
command or "trim with surface" to shape the end of the tubes. You may find
it useful to use separate layers (and colors) for the tubes during
construction for clarity at the intersections, then use edit/layer/change to
current layer   to get them all the same color when you are done.

      After your frame is drawn do a copy of each tube and drag them to
someplace away from the frame. Then you can measure the overall length
endpoint to endpoint and the various angles of the cuts to set your joint
jigger during fabrication.

     After using the software for a short time you may want to just extrude
"pipe" from one intersection or  point to a relative coordinate. I find it
difficult to get the correct snaps doing this, but if your goal is to do a
rendering of an idea and not be designing an actual part for fabrication its
a good approach. Another shortcut is to extrude a surface or pipe to another
surface which is self trimming from the second surface. In this case you
would be joining to the side of another tube such as the short stubs bolted
to the engine and firewall.

       As a final thought, you can make a copy of any stage of your work in
case you want to develop different things off the same geometry, like a view
with oil cooler mounts added, or one with the engine installed on the frame.
Keeping all your tubes unjoined you can join a copy with the "fillet"
command which will simulate the welds in the render. When you are finished
do a file "save as" with a different file name like finished motormount and
erase all the construction stuff of this copy.

george grimes