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 curvelinesingle linetoolsobject snap point

that gets the first one then

toolsobject snappoint

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



Paul,

Attached are two files of the finished motor mount frame as made by SMA.
I cut the  dynal focal  mounts cut off and the rendering doesn't
accurately depict those short 2" diameter angled pipes.  Not to worrry,
I will attach a thin 6mm thick firewall  to this frame as well as mount
tubes similiar to what  Bob did.  Bolt or weld?  I want to make a PSRU
mount similar to what Dave Garber did.  I lost those pictures in the
computer crash of 2009, so can you resend them to me?

http://www.youtube.com/watch?v=Mo1fhLxtYI0&feature=related

Distance from from mount bulkhead to front is 831 mm, an accurate
measurement.  Total distance from mounting bulkhead to prop  is 1834 mm
or about 72.2 inches.  Adding a 6mm (firewall) I have 997mm almost three
feet to squeeze the engine and PSRU into.  YES a P-ported 20B is
possible as well if I decide I later want a hot rod.  Plenty of room for
tanks and oil filters on the firewall. Engine will have both water and
oil exhangers underneath.   Fluidodyne got back to me with some good
info.  I forwarded to you last week. Cowl width is 24" in the latest
sketches but of course I would like it thinner.  There will be a turbo
bulge though and I am thinking maybe of making a thin insulated
stainless sheet metal box around the whole hot section and incorporate
the outer skin as part of the cowl.

Plenty of room for a axial turbo compound feeding into the accessory side
as well in a future version.

Need to put the batteries in the rear frame now to correct CG imbalances
but this frees up the nose compartment for baggage and loses a lot of
weight in heavy wiring runs.


George,

Many many  Thanks for your through and complete suggestions. That post
took some time and helped move me up the learning curve significantly. I
greatly appreciate it.  I was able to try many things and finish the
drawing that is not 100% accurate in the little details but spot on
(excuse the pun at the four attach points that matter.  From here out I
will try tubes.  Pipes (shouldn't they be called rods?)  are good for
illustration but  extending tubes accurately to coordinates is what I
want to do.
Going for an extreme front and back four point bed mount.

One question.  How to create parts in different colors.  Is it a layering
thing?  Choosing display colors?   Rendering objects always leaves me
with a gray object but that may be because my beta version only comes
with Toucan renderer.


Cheers

Doug


Doug, The layer control box in Rhino 4 is on the right side of the upper
tool bar it looks like a slice of pie and is red yellow and blue. In it you
name a list of layers (new layer) which will default to white. click the
white icon and you pick  a color from a list or a color wheel for extra
colors. If you havent set up any layer colors you will be in "gray scale"
Click on the space beween layer name and color block to make it current. A
check mark will indicate it is current. On the bottom toolbar the block of
the color will display. To change already drawn objects to a color, select
the layer (checkmark) go to File/Layer/ and choose "change to current layer"
from the list. anything you click on or window will change to that layer's
color.
      Rhino models in surfaces rather than solids. You change them to
solids in the solids menu with things like "cap planar holes" or "convert to
solid"   If you draw two concentric circles of tube ID and OD  then use
Surface/ "From planer curves" to make it a surface. Select both circles (to
get a surface between them). Then you can use Solid/ "extrude surface" to
make tubes that are solid tubing. There are at least three other ways to end
up with the same thing. One interesting one is doing the outside of
something and using the "shell" command to hollow it out like an egg shell.
This is best left to make a cowling or fusaloge of a specified thickness.
When you extrude anything (wihout guide rails) it will be perpendicular to
the surface or curve you are extruding. Tapered or straight it is
perpendicular. If you "extrude along curve" and snap to a line it will
follow it. The easy way is to make a construction plane perpendicular to the
line you want to extrude along and draw your tube section on it. Then the
extrusion will be perpendicular to the plane and  along your center line.
The construction planes can be deleted  (click on and hit the delete key on
the keyboard) the same way as a line. Alternately you can select and then
"hide" on the bottom toolbar to make it invisible. Construction planes seem
to be unnecessary complications as you are learning but when you are more at
ease with the software they are quicker than drawing objects and rotating
them 3D to work with your diagonal tubing. In the meantime try "circle
about" and use a perpendicular object snap to your diagonal and snap to the
nearpoint on the line. For the ID of the tube snap to "center" of the first
circle to make them in the same plane (coplaner).

      Rhino ships with Toucan as the render which is much more featured
than the previous flamingo render.  The trick is to tun it on. When you
select RENDER go to the right side of the line and click "Rhino render"
which will put you in it. Turn the lights up to 75% choose lighter colors
with a lot of contrast top and bottom and a plain solid backgroung color
with contrast to your render colors. You can also tie it to "by layer" to
use your layer colors.

      Something you havent asked about is important. Go to File/Preferences
and set tolerence to .0001" or .001mm  on parts less than 10' long. When you
start a new drawing open this drawing do File/Save as to rename it then
erase the renamed drawing. That will start you off with a configured drawing
with layers and colors defined. Also go the dimensions on the top toolbar
and select preferances to set the displayed tolerance of dimensions on the
drawing to .001 MM or .0001 inches, otherwise everything displays to 1.0 of
the "units" you have selected in File/Units. The accuracy is in the units
and tolerance settings no matter what you display as dimensions. it just
can.t be higher than the units tolerance. Setting really high tolerance
numbers makes the file size  large.  My rotary engine side housings are 292
mb at present and I regularly "save as" an erase anything I don't need. My
airframe is 798Mb all in drawings and wireframe. The engine parts include a
lot of solids which greatly expanded the data size.

      I have only used this software for 3 weeks and am in the learning
from mistakes phase. I just click on anything where the discription sounds
right and see what it does. In the help menu of the upper toolbar you will
find examples and a list of most of the commands, some of which can be
accessed only from the command line as can all the commands in the menus. I
downloaded manual 1 and manual 2 but don't remember where. It took several
evenings to find them. The educational version I have didn't come with the
manuals and I was to cheap to pay $80 for them. The software is wonderful
and well worth the price.

george grimes