Howard wrote:

Paul:
    I inquired of one small commercial foundry which does cast iron & steel
about making a part for a backhoe.... about 300 lbs for me.    If I made the
foam pattern so that they did not have the pattern development problem cost
was $1.50 per lb for iron, and $2.00 for steel to have it poured.  Aluminum
would likely be more.    To make a waterpump casting on a series basis would
require a permanent pattern from which molds could be made.  The key is to
keep it simple..... not too many cores, and relief angles on things so that
the pattern can be drawn easily from the mold.   Large scale operations
often use expanded polystyrene foam which comes as a powder which can be put
in a mold and heated to expand it.... this technique is used for egg cartons
and foam cups, coolers, etc....   A complex casting can be made of several
pieces of foam made seperately and glued together before making the mold.

Not to mention the Saturn engine.

        The guys I mentioned are more that just hobbiests....they have grown
into small commercial foundries...... If you are contemplating such a
project get with one of them and discuss your requirements and theirs.
Often such an item has enough design flexibility that one can design it to
both serve your purposes well and make casting easy and inexpensive.   Don't
just say this is what I want.... can you make it.... say this is
approximately what I want....how can I design it so that it is easy and
inexpensive to manufacture.    Use off the shelf impeller & impeller casting
to reduce casting and machining complexity, and to allow replacement of a
worn out bearing and seal without danger of breaking the pump casting itself
in the replacement process (pressing)..... not to mention being to purchase
the needed part at the local parts house.

                                                            H.W.

Our intention is to use the stock Mazda water pump cartridge or a Chev or Ford
water pump cartridge. Those contain the bearings, shaft and the impeller.
All we need is the housing.

Paul Lamar
 
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