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42216Re: Spray type mold release?

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  • Lyle
    Oct 3, 2012
      That's exactly what I used over the paste wax. By the way, smooth - on is absolutely the best stuff I've ever used (for making rubber molds). I use the brushable silicone and like it better than the urethanes. The spray on release worked OK on my simpler wood oil cooler pattern but it was still a hard pull from the sand, it didn't work so well on the heads, if at all. I've got an idea that will work but it'll take some redoing of the pattern before I'm able to try it. That and I didn't rap the pattern prior to the sand setting up. The reason being is I didn't want to cause stress fractures in the sand between the fins. And I never rap anything that was made in SS sand so why resin sand? But I'm going to cast an oil cooler this weekend (far less sand to waste if it doesn't work) and rap the pattern before set up. In the meantime I'm modifying my pattern with some stronger inserts so they don't pull out of the pattern before it's released. It's a lot of work though turning them all out on my lathe and then threading them.
      LL


      --- In hobbicast@yahoogroups.com, Rupert <rwenig2@...> wrote:
      >
      > Hello Lyle,
      > Did you try a spray something like this
      > <http://www.smooth-on.com/Release-Agents-for/c1123_1226/index.html> in
      > lew of the paste wax? I've used it on over shellac and RTV rubber but
      > haven't tried it on metal to make SS sand molds.
      >
      > Rupert
      >
      > On 10/3/2012 11:18 AM, Lyle wrote:
      > > Not a bad idea Rupert. One of the main problems is getting the Johnson's wax between all the fins. Seems easy but there's bolt bosses and a spark plug boss that's raised up between them so there's a lot of different reliefs going on. Heck, some of the problem could be my lack of patience which has nixed me before....
      > > Thanks,
      > > LL
      > >
      > >
      > > --- In hobbicast@yahoogroups.com, Rupert <rwenig2@> wrote:
      > >>
      > >> Hello 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.
      > >>
      > >> Rupert
      > >>
      > >> 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
      > >>
      > >> --
      > >>
      > >> yvt
      > >>
      > >> Rupert Wenig
      > >> Camrose, Alberta, Canada.
      > >>
      > >> email: rwenig2@
      > >>
      > >> http://users.xplornet.com/~rwenig/Home/
      > >>
      > >
      > >
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      > --
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      > yvt
      >
      > Rupert Wenig
      > Camrose, Alberta, Canada.
      >
      > email: rwenig2@...
      >
      > http://users.xplornet.com/~rwenig/Home/
      >
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