There are many things that can contribute to porosity. Poor spueing,
inadequate burn out and/or mold temperature to high.
I have been vacuum casting using an Electro-Melt for at least 30
years. I use both the 30 and 100 ounce unit.
The big advantage of using an automatic furnace is consistency in
melt temperature. Once you determine the best setting for the melt
temperature that setting of temperature can be achieved with each
One problem with the electric melt furnaces is the time it takes to
achieve the required temperature. It can take up to 45 minutes to
melt the metal to pouring temperature. The advantage to the
controller unit is you set the temp an let it heat up without
Another problem is the cost. The cost of an electric type furnace
may not be justified unless you are doing a lot of casting.
The smaller unit would work best for you.
You can melt enough metal for several pours.
Its best to not fill the crucible to the top. It is a little
difficult topour from a fully loaded crucible.
Let the unit set for about 5 minutes after reaching melt temperature
and between pours. That delay allows the upper part of the crucible
to heat up. Metal will be chilled if it is poured over the cooler
upper ring of the crucible.
You might want to check out Rio Grandes Automatic Melting Furnace.
It is the less expensive but is still pricey.
I don’t recommend the unit that requires removing the crucible to