<Snip>
Paul - I am sure that I could turn the "bowl" for the bell
housing
on my
lathe
using wood as the pattern material. The other parts could then
be
pieced on rather easily. With a bit of draft and planning it
looks
like
it could be a simple cope and drag sand casting with no fancy
coring. I made aluminum cast wheels for a sports car project
about
25 years ago - Vance J
That is the hard way. It only takes me a couple of hours to make
a pattern. Not only that it does it while I sleep :)
The big thing is the .010 accuracy possible with 3D. You will play
hell turning a bowl only .2 inches thick with a constant wall
thickness by hand. The entire lower half of the pattern is
a box. Mainly due to the necessity of mounting the starter.
then you have the vertical walls on each side needed for the
motor mount brackets. Not to mention all the drafts needed on
all the interior reinforcing webs and all the walls. Then you
have fillets on all the junctions between interior webs and
the outer walls. It could take a month of hard work.
Hand made casting patterns in the age of Rhino and 3D machines
are ancient history.
Paul Lamar
david mccandless wrote:
Paul, I'm not getting a picture of the bell housing rhino, could you
send it again please? (Dr Wankel at NSU did it in millimeters,
Yamamoto
at Mazda did it in millimeters, What's this inches mumbo jumbo?
Yeah, I
know, the shuttle is in inches! Luv your work Paul! Dave McC
I am too old to change Dave :)
Paul Lamar
I'm with Dave. I may be a mechanical engineer, but I'm too staid in my
T-square and woodshop ways to make the switch to computers and 3D
machines.
Besides, I don't have *those* in my basement!
Since I have more time than $$$, some pine and a wood lathe will win out
every time. And yes, I can hand turn a cylinder or cone to a 0.01"
diameter
tolerance. After roughing with a skew chisel, I use a finely set plane
to
smooth the contour to within ~0.03" oversized, and sand paper for the
rest.
Works great (except on @*#&&*# endgrain... that doesn't sand evenly!).
Tom Kendall
I think Dave was talking about the metric system verses the inch system
Tom.
Cones or cylinder are one thing but when you get beyond those that's where
the computer really pays off.
Tom you really need to try high density foam. Works like wood but
there is no grain.
http://www.freemansupply.com/PolyShapeIIPolyure.htm
OK Tom you do the pattern and work a deal with Tracy. It will
save him some machining time and a bunch of long 1/4 bolts not
to mention a few pounds. I will help with initial financing,
act as liaison with the foundry and provide some marketing
help through the news letter.
If it looks a bit like the Ross is should as Ross got it
pretty much right. All walls are .2 inch except where
necessary for bearing mounts.
BTW it loads the gear set through the back just like a car
transmission. It can be retrofitted with Tracy gear sets already
out there if someone would like to upgrade. Me for one.
Paul Lamar
I've been watching the progress.....Now, it looks like you really have a
marketable unit ! Paul Conner
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