>> Larry delivered the pattern by driving down from Northern
California>> Thursday after noon. We drove it over to the foundry today and
>> it passed inspection and left it there.
>>
>> In fact they complemented Larry on the nice work. I am relived and
>> very happy.
>>
>> We will have ten castings next week. Larry is building a
>> test rig so they will be static tested to 600 foot pounds. The
same
>> torque
>> will bend the flange on a Lycoming aerobatic motor so any more than
>> 600 foot pounds does not make any sense.
>>
>> Paul Lamar ...No rotor no motor.
>
>
> Sorry if I missed this in an earlier post (and my ignorance):
what is the
> exact technique used to cast a housing with this pattern?  Is it
lost-wax,
> or some other method?
>
> Scott Gettings
>
> Straight sand casting Scott. The foundry we use specializes in
thin wall
> sand castings. The lost wax process would be too expensive.
>
> -- > Paul Lamar ...No rotor no motor.

An interesting point Paul, and I was interested to see how you and Larrytackled it - is that a lot of casting companies want an inner and an outer
pattern (dowel matched). That method is expensive and time consuming.
I noticed that Larry has made one pattern, which is used as an inner and an
outer ( same as the method I used). The pattern is placed flat on the back
surface ( within a frame), sand is packed around it and then it is turnedover. Another frame ( shorter) is placed over the top of the first and the
inside is filled with sand. The frames are split at the junction -
maintaining true symmetry ( inner to outer).
Copies of mast things can be achieved using this method, provided the copied
item can tolerate the 1:22 shrinkage rate i.e. difference in finished sizes.
BTW did you leave about 5mm clearance on the flexplate to
Bellhousing?
George (down under)

Yes.

Paul Lamar ...No rotor no motor.

The reality is that machining two molds would have been just as, if
not easier than doing the full pattern in one pc. It would have ment
twice as much wood, but the setup's would have been way easier.
I was going to suggest it, but knew it was not the 'normal' way of
things so I kept my mouth shut.. anyway.. I can't wait to see the
cast parts!

Jarrett

Jarrett,
Good to see you involved to that extent and I agree with your opinion in
this case, especially with using CNC, I am concerned with the thin timber
warping with use and over time.
However in my case where I have to do things by hand it is so much easier to
do it this way (one pattern). Of course the other point I was making was
that this method can be used with existing items that you want
remanufactured - that was included as an educational tool.

The proviso was that you need to be aware of the shrinkage rate. For
instance you couldn't remanufacture form Paul's/ Terry's/ Jarrett's cast as
the final item wouldld't have sufficient clearance for the flexplate.

I also tried to highlight the advantages of thicker areas, that benefit the
flow to thinner areas, as an educational tool to future budding designers
( not preaching to the converted, people such as are involved in this
exercise, already know these things).

All in all, great teamwork - I wish I had you chaps locally!
George ( down under)


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