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Re: [multimachine] For Jeremmy, one view of sand casting aluminum faceplates - Fwd: [castinghobby] Re: Did my first lost foam sand casting today

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  • Pat Delany
    Thanks Dave! good stuff that Jeremmy will see when he gets back home Pat ________________________________ From: David G. LeVine To:
    Message 1 of 2 , Apr 16 8:43 PM
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      Thanks Dave!
      good stuff that Jeremmy will see when he gets back home

      Pat


      From: David G. LeVine <dlevine@...>
      To: multimachine@yahoogroups.com
      Sent: Tuesday, April 16, 2013 10:35 PM
      Subject: [multimachine] For Jeremmy, one view of sand casting aluminum faceplates - Fwd: [castinghobby] Re: Did my first lost foam sand casting today

       



      -------- Original Message --------
      Subject:[castinghobby] Re: Did my first lost foam sand casting today
      Date:Mon, 15 Apr 2013 16:42:38 -0000
      From:rogers92026 <brogers9941@...>
      Reply-To:castinghobby@yahoogroups.com
      To:castinghobby@yahoogroups.com


      I've poured a few faceplates or equiv in lost foam.  For me, flat things in lost foam pour better in the vertical orientation and I'm less likely to have the weight of the sand deform the pour.  Also, in the vertical, there is less of a chance of there being a sand void under it. (But when I'm doing green sand casting, I cast it horizontal. Also, now when I cast a faceplate I'll do it in green sand with a nice pattern.  That way I can make additional faceplates if I need to).
      
      For vents, I sometimes use plastic soda straws that I've lightly plugged the upper end with tissue paper (that keeps the sand from trickling in before I pour).  When I pour, the paper quickly burns up and gets out of the way.  The vents can either go all the way to the top of the sand or can be buried vents.
      
      When I've made faceplates, I initially wasn't happy with the surface finish after machining.  Like most casters, I wanted to machine the casting the same or the next day.  Even though I was using aluminum ingots from a transmission case (A356 type), it seemed a bit gummy.  I would be almost done facing off and would get a little build up on the tip of my tool and it would leave a gouge in the face.  With the advice of others on this group and from Google research I have since minimized that by going through some red-neck heat treating.
      
      What I do for my heat treating is to pull the metal casting from the sand when it is solid but still pretty hot (maybe 500-700 degrees) and then I dunk it in water.  After it is cool enough to cut off the sprue and risers, etc., then I put it back in my cooling down furnace.  In my case, the furnace is a small kiln.  After I have poured and it is turned off, I wait for it to be around 600 degrees of so and then put the casting back in.  I let it soak with a very slow cool down.  I have also used my wife's oven at 450 degrees for an hour, but SWMBO gets a frown on her face when I do that.  
      
      When aluminum was first invented and cast, the inventor initally was very disappointed with the softness of it,  but he was surprised that over a period of 30 days or so, that it aged and it's mechanical (and machining) properties changed.  Same thing with my castings.  The heat treating artificially ages it.  I think that just putting it on the shelf for 30 days might do almost as well. But few of us have the patience to cast something and leave it sit that long.  ;-)
      Good luck on your casting adventures.
      
      
      --- In castinghobby@yahoogroups.com, "andrew7899987654" <etownandrewg@...> wrote: > > Making a face plate was just the first step to allow me to machine other castings. So yes probably more to come. > > So you think the vents were helpful but where I brought them to the surface you would not. That would make less of a mess too as a lot of the aluminum that I had poured into the can came out the vents. > > I am almost finished machining them. The face plate surface has a slight dish in it like 1/64" to 1/32". I am thinking that either the metal on the outside rim is springing or my tool setup is less rigid out that far. Either way I will try to reset and make a fast clean up cut with a sharp lathe tool to try and get it all flat. > > --- In castinghobby@yahoogroups.com, Malcolm Parker-Lisberg <mparkerlisberg@> wrote: > > > > Andrew > > > > A successful first casting, you are now infected with the casting virus. > > If you cover the top of the vents with sand then the molten alloy head you then get in the sprue feeder will supply metal to the part as it shrinks with cooling. If you also spray the hot part with water as you extract it from the sand it assists in removing the sand trapped on the casting surface and improves the machinability of the casting. > > > > Malcolm > > > > > > I don't suffer from insanity I enjoy it! > > > > Mene, mene, tekel, upharsin > > > > The writing is on the wall. > > > > --- On Sun, 4/14/13, Andrew Willis <etownandrewg@> wrote: > > > > From: Andrew Willis <etownandrewg@> > > Subject: [castinghobby] Did my first lost foam sand casting today > > To: castinghobby@yahoogroups.com > > Date: Sunday, April 14, 2013, 4:55 AM > > > > I did my first lost foam casting today. It seems to have turned out well. I am making a 6" face plate for my small hobby lathe. I was a little nervous about how it would do and so I ended up combining some green sand methods by putting in the two vents and packing over the top of the part with green sand. I am not sure if that was needed. I poured a lot of extra into the top which seems to be recommended. The main defect is that the disk developed a 1/16" cup across the face. Probably from my packing sand onto it. However, I made it extra thick so I could face off some anyway so that will be ok. > > > > > > Andrew > >


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