42212Re: [hobbicast] Re: Spray type mold release?
- Oct 3, 2012Hello Lyle,
My words weren't clear and I assumed your using sodium silicate sand.
Johnson's paste wax should work as long as you have complete coverage. I
meant to fill the spaces between the fins with the SS sand, pack it only
firmly (don't ram it). Rap the head on the side so the sand loosens a
bit. Then, gas it to harden. I think the hardened mix should fall out.
Do this for every space. Place them in place between the fins and make
the complete mold again using SS sand as it should bind to the
previously made fin cores. Only a firm packing is needed- don't ram it.
Again, rap the head enough to loosen it before gassing. The head should
fall out when you turn the flask over provided there are no undercuts to
consider. Don't know if this will work with other types of resin set
sands. But, I do think the SS sand should work.
On 10/2/2012 9:27 PM, Lyle wrote:
> Rupert, Thanks for the idea but the pattern is one piece. Today after
> work I used a masonery bit to free the pattern out of the sand which
> looked a little like sandstone. I have another oil cooler pattern
> which has similar depth fins but not as many that I used as an
> experiment for the head castings. I am going to try a reduced amount
> of binder to see if that helps and less ramming of the sand. Usually
> deep fins need to be jolted, which I did, but I also rammed, so I'll
> try jolting. the learning continues....Part of the problem is me
> using Johnson paste wax as a release but it's hard to get it between
> all the fins which are about 1/4" apart and 2" deep. LL
Camrose, Alberta, Canada.
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