Paul,
You wrote:
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 :)....
Hand made casting patterns in the age of Rhino and 3D machines
are ancient history.
I don't follow every thread but I think I have missed something big here.
I have two radial engines that I have been asked to build for a friend. The
most difficult part of doing these engines is making the patterns for the
castings. I have two CNC Bridgeports and a new 13" lathe with DRO to do the
machining on. My copy of Rhino 2 has just arrived at the PO for a pick up
tomorrow.
(I have been a long time user of Solid Works and AutoCad 14. I ordered Rhino
based on your raves and excellent examples of various engine parts.)
Would you please take a momemt or two to briefly fill me in on how you are
making patterns using Rhino?
I am a long time rotor head starting back in 1977 when I bought my first Rotary
Pick Up. I am presently finishing a Locost 7 which is powered by a 1987 Turbo
II engine. I have also been working on and off on building a turbo-charged
single rotor Rotary for a Slepcev Storch that I am building.
Many thanks for this news group. Hope it continues for a long time.
Sincerely,
Walter Luikey
Dracut, MA
Interesting project you have there.
Don't forget to download the 2.03 service release from the Rhino web site
as it will be gone after the first of the year. The CD does not come with
the bug fixes.
I think you will like the user interface on Rhino much better than Solid Works
but I could be wrong. Once people use a program for awhile they kind of
get locked in. I found it much much easier to learn than Solid Works
and I have been a long time user of ACAD starting with version 6
up to 12 on DOS and then it got too slow for my taste.
It is way more than a couple of minutes :) Here goes a few tips.
Before most 3D prototype programs will accept objects for conversion
to 3D machining G codes they must be what is known as a "water tight solid".
There in lies the rub. When ever possible join your curves.
Use union of solids often to make sure your complete objects
are water tight. You can use Analyze > Find naked edges to discover
trouble spots. Then use Join naked edges.
The people at Rhino tell me 3.0 is much better at
the boolean operations such as Join, Difference and Intersection.
That is very very important.
You should be able to get a free upgrade to 3.0 if you just bought
2.0. Under Dimensions > Properties set the tolerance to .0000001
or lower. That seems to help the boolean operations. Also under
Edit > object properties > object > isopam density set the density
up to 6 or 10. That also seems to help trim and a few other commands.
Unfortunately it slows filleting. I think solid Works does a better
job on filleting. There are a lot of little tricks I have learned
over the months and the order things are done is is very important.
It is very much like programming in that regard.
Drafts must be done manually in Rhino by trimming with
surfaces while Solid Works has that feature. Also shell must
be done manually. I usually do those by copying the solid object and then
scaling the solid object copy in one or more dimensions.
Then do a difference.
I am just scratching the surface (pardon the pun) and I have a whole
lot more to learn. In any case feel free to send me your problem 3dm
files and I will see what I can do to help.
You will also need a book on sand cast pattern making. The best one
I have found so far is Wood Pattern Making by H. J. McCaslin
first published in 1923. Reprinted by Lindsay Publications.
I am still learning things when I go over to the foundry.
Mostly by my serious errors :) I have had to redo a few things.
One must totally understand and keep the sand casting process
firmly in mind when doing the patterns.
BTW If you find a good book on foundry technique let me know.
The art of sand casting is well over a 1000 years old.
Paul Lamar
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