[SEL] 8hp Blackstone/cast engine plate

[Rupert]

Hello Jerry,
	Making sodium silicate/sand cores is relatively a simile process once a 
core box has been made. Each core is different so how the core is made 
varies.
	The sand I use for cores is fairly coarse (about 80 grit size). There 
shouldn't be many fines as the sand needs to be porous for good venting. 
The sodium silicate is formulated special for foundry use. The SS I use 
is "Carsil 310" manufactured by Foresco. The additives help reduce the 
strength of the sodium silicate and make it solvable in water. Finer 
grit sands can be substituted to get a smoother finish but great 
attention must be given to venting.
	It's been awhile since I actually measure the quantities. I add enough 
SS (Carsil 310) to the sand and mix well to get a very stiff cookie 
dough texture. I fill the mold with the pattern in place with the 
mixture and pack it only hand tight making sure there are no voids i the 
sand. The pattern has to be placed taking note of the draft angles as 
for normal sand casting rules. The mold can be left sitting on the bench 
to absorb CO2 from the air or a shot of compressed CO2 can be injected 
into the mold as this point. The amount of injected CO2 depends on the 
size of the mold. An example, I recently made a core for the standard on 
a 3/4" bore vertical steam engine. That took about a 15 second shot of 
CO2 at 3-5 psi to set the sand/sodium silicate mix.
	The core can be used in a normal sand (green sand or petrobond) mold at 
this point to make a casting. I like to warm my cores at 250°F to make 
sure there is no moisture in the core prior to inserting the core in the 
mold.
	The next step is fill the mold with the metal of your choice, let sit 
until the metal has had time to harden. Sometimes it is better to let 
the metal cool in the sand mold before shaking it out. Shake out the 
casting and hopefuly you can admire a good casting ready for machining.
	In the case of the plaques or engine plate: I have poured plaques using 
only petrobond sand and green sand with good results. I think I would be 
inclined to use a petrobond molding sand for a one of plaque possibly 
using a thin layer of facing sand of finer grit size next to the pattern.
	Is this what you are looking for?

Rupert

On 5/25/2010 11:52 AM, Jerry Evans wrote:

> Hi Rupert,
>           Please tell us more.
> Jerry
>
>

-- 

yvt

Rupert Wenig
Camrose, Alberta, Canada.	

email: rwenig2 at xplornet.com
	
http://users.xplornet.com/~rwenig/Home/