Do you Need Engine Parts???

After reading some posts on engine parts I had an idea. I know a guy that has a spin caster machine. A spin caster can duplicate almost any type of metal part in aluminum, zinc or brass.

Here is how it work. A spin caster uses rubber molds. A rubber mold can be used over and over again several 100 times until its worthless. Molds come in several sizes, 6", 8", 10", 12" diameter.
You lay your parts on the rubber mold then put another rubber half on top. You squeeze the mold in an oven for about a hour and the rubber melts around the parts. This is a thermoset rubber that will not melt a second time. You remove the parts from the cooled rubber and place the mold in a spin caster machine. You pour in hot metal and centrifical force pushes all the liquid metal into the cavities. Open the mold and remove all the cooled parts. You can do this over and over ever few minutes. A 6" mold would hold about 30 or so engine connection rods or other tiny small parts.

It would not be practical for a mold to make all 30 parts the same. If a mold made 30 connecting rods all for the same engine you would not be able to sell them all and you would need lots of molds to make other parts.

It would be practical for a mold to make 30 connecting rods for 30 different engines. A 12" mold could make 50 connecting rods, engine heads, thrust washers, venturi, pistons, crank case covers, elevator control horns, bell cranks, and many other parts all at the same time. A 12" mold could probably make about 100 misc parts at a time.

This may be a chance for everyone on this forum to get the parts they need at a very reasonable price. I am guessing a connection rod would cost no more than a $1.00 each. I know this guy will not be interested in making a mold to make only a few parts. It won't be worth his time and trouble if he can't make some money. The Guys name is Ken Sergeant he lives in Murfreesboro Tennessee. His phone number is 616-896-1591. I don't need any parts myself so I suggest maybe someone on this forum give him a call and see what you can do.

Ken will need real parts to copy. So anyone that wants a part needs to supply the part to be copied. It must be a good part because the spin caster makes duplicate parts. Think of it as a counter fitting machine that makes copies of parts. If you supply bad parts it will reproduce a bad part. If you supply good parts it will reproduce good parts.

I've made molds for this type of caster. The raw rubber and the pattern parts are layed up in a steel ring with fitted lids, clamped shut and heated to vulcanize the rubber. Let it cool, peel the halves apart and hand cut the runners and vents. Then it is clamped in a machine that spins and allows molten metal to be poured into the center and spun into the cavities. There are two types of rubber: silicone, more flexible for complex shapes, and dark rubber much like that in tires that is more durable but stiff.

A common use for this system is casting "pewter" sculptures and do-dads. The pewter is essentially glorified solder and can be melted in a pot like bullet casters use.

I don't think the rubber will tolerate the temperature of molten aluminum, and would want some data about the accuracy and repeatability of the process for machine parts. But it is worth researching.

You still have to find or make as many metal masters as you want duplicate parts in each mold.

Interesting thought though. Certainly cheaper and easier than die casting, forging or machining from stock. Detail reproduction is very good. That's why it is popular for small inexpensive sculptures.

Ken made a copy of a World War II German Pistol on his spin caster that really works. He said the hardest part to make was the slide because it was so large.

You are right about extreme detail. If a part has a tiny scratch on it the mold will copy it. Ken made a copy of a dime and you couldn't tell the difference between the real dime and the copy.

The spin caster is basically for small parts. It will reproduce parts so perfect they do not need to be machined in most cases.

Ken says the rubber molds can be reused about 500 to 1000 times with zinc. Zinc can be poured into the mold at 850 deg F. Aluminum melts at about 860 and needs to be poured at about 1400 deg so a mold can be reused about 200 times with aluminum. Bronze or brass pours at about 1800 deg and is very distructive to the mold. A mold can be used 50 to 100 times on brass depending on how large the parts are. Large parts stay hot longer and cause more damage to the mold. Small parts cool fast and cause very little mold damage.

This is totally from memory. Ken is the expert on this. If you have had some experience with a spin caster you might want to make model engine parts yourself.

A little off topic, and maybe paranoid, but you really shouldn't post a guys phone number on a bbs. Lotsa crazies out there looking for Honda mechanics that specialize in Krylon. Your friend could find himself up to his eyeballs in weirdos.

Otherwise, purty cool idea!
From somewhere near Parkville, Mo.
William Crane
AMA 6733

Note too, that there will be shrinkage to account for. The finished piece will be a few thousanths shorter than the original. Might not be a big issue, but should be accounted for.