On Jan 12, 8:38*pm, "Maxwell" #$$9#@%%%.^^^ wrote:
-----------------------------------------------------------------------------------------------------

First, I would recommend you double check your source on sand.
------------------------------------------------------------

BT, DT (big Smiley)
This is good quality 100% silica. They don't even store it in the
same shed, to prevent errors (They'll load stuff for you.).

I've got a couple of bags of #80 but I've found it's a bit too
coarse. (But works fine in the blast cabinet.)

------------------------------------------------------------

I'm not familiur with your binder recipe,

-----------------------------------------------------------

I may not be either :-) I think I used 'Karo Syrup' the last time I
made cores but I had a rather unfortunate accident with the
materials. We have cats and... perhaps that's enough said :-)

----------------------------------------------------------

but might want to try a sodium
silicate based solution to simplify your process. You can mix a one part

----------------------------------------------------------

I've seen this used to make some brass castings, literally while the
'customer' was waiting (circa 1975) I've always wanted to try it but
applying the gas makes it appear rather complicated. Of course, guys
who HAVE used it tend to make it sound like mother's milk, whereas
guys who have TRIED to use it make it sound like WWIII. I assume
it's somewhere in the middle :-)

---------------------------------------------------------

. I'm told it's about $75 for 5 gallons

---------------------------------------------------------

Then it's beyond my means. (The cancer has attacked my pocket-book
with even more success than my spine :-)

And besides, I still have the patterns to finish and prove. The last
time I worked with fins I had a HELL of a time before I got the patten
to 'rap' free. Indeed, it made cores simple by comparison.

I will also have to develop the procedure for afixing the valve seats,
hopefully like Stephen.... what's-his-name... the fellow who did so
well racing the Type IV's. His foreman let me try my hand swaging the
seats into a modified Type IV head and that puppy was HOT -- it came
right out of the oven. (Do it COLD -- which was VW's recommended
procedure -- and you'd end up with a loose seat for sure.) Plus the
racer's seats were something like 5/8" deep; VW's appeared to be less
than 1/2". So there's a bit of tooling needed on the production side,
assuming I can get the thing to give me some fins.

....but you've got me thinking about using the CO2 method for the outer
mold as well. Give me another hundred years... or even ONE :-)
--------------------------------------------------------------------------

There is also the possibility of molding this in plaster, but that's another
story.
---------------------------------------------------------------------------

I think I mentioned the dentist. He was casting some exotic STEEL
alloys for bridge-work using the lost-wax process. Had a little
centrifuge, tiny ceramic crucibles -- the whole nine yards but in
miniature. He let us use his oven to heat-treat the hinges for the
Varieze. But only once :-) When I tipped the tray of hinges into the
ice water it drove everyone out of the lab. I guess he'd never seen
it done before.

-Bob