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



George

Thanks.  You have been more helpful in five minutes of reading then the
ten hours I have spent wading through the 500 page Inside Rhino 3 book I
bought several years ago.  With the Mac beta version behaving fairly
well now I am a happy camper.  I bought a wireless mouse with this new
dual processor Mac and it really makes zooming, dragging and accessing
the menus a one finger operation.

Per your suggestions.  Yes the tolerances are set at 0.001mm and I can
change colors in layers and display them.  It just won't render in
color.  Some features are not enabled yet in this under- development
version and this might be one of them.  I am finally going through the
tutorial menu  to learn the ins and outs of the program.  I still need
to do a paper sketch and then transfer that to 3D but I'm slowly
learning some routines.

I'll import one of the multicolored data files Paul has given me on CD
and see if I can understand the settings he used. I am happy to hear
you are making real accurate models of the housings and hope to obtain
some when you are finished.  Perhaps I can contribute the Bell 47 PSRU
model and mount plate if anyone wants to copy it.

Cheers

Doug