Granite surface table are fairly cheap anymore.
http://www.grizzly.com/products/searchresults.aspx?q=surface%20plate&new=1
might be better in the long run just to by one.
Dave Patterson
odd_kins@yahoo.com
http://home.comcast.net/~oddkins/foundry_home.html
--- On Sun, 2/27/11, james <james122964@yahoo.com> wrote:
From: james <james122964@yahoo.com>
Subject: [gingery_machines] Re: New Here
To: gingery_machines@yahoogroups.com
Date: Sunday, February 27, 2011, 1:33 PM
I do not know what the alloy(s) are. The metal is castings from the end of electric motors, electrical condiut connectors (which I think are just zinc). I have 50 lb of solid aluminun 3 * 4 * 1/2 angle which I will use if it is better, I had considered that it may be best to use since it will be enough to make all the parts from one metal.
I had planned on supporting the granite cut out with 2 * 4 framing, I will check at the tombstone place, thanks that is a really good idea.
thanks
Jim
--- In gingery_machines@yahoogroups.com, "Local" <charcad2006@...> wrote:
>
> > 1. Is there any difference or does it matter if I use zinc die >casting alloy instead of aluminum?
>
> There's a difference but it doesn't "matter" for many parts (given that we're using Al and not Fe). "Pot metal" is a generic term that has included zinc alloys at times. If you have access to a real Zamac alloy by all means use it. The tensile strength is greater. Atlas Press made a large array of lathe, shaper and horizontal milling machine parts using Zamac.
>
> Gingery specifies "pot metal" for some parts, such as the split nut.
>
> I personally wouldn't try using zinc for the bed, headstock or tailstock. Zinc is susceptible to cracking from "zinc pest" over time. otoh hydrogen gas in the aluminum melt leads to weakness and cracking there, too.
>
> > 2. I have read that granite counter top material is flat to greater than .001 inch can I use such for the surface to scrap in my parts?<
>
> I have a piece of granite counter top in my shop covering part of the top of one of my workbenches. There is noticeable flex in it when it's moved. Maybe 1/8" over 4' length. At 1-1/4" to 1-1/2" thick this material is just too thin to be rigid enough to serve as a surface plate.
>
> Before granite counter top could be used successfully as a surface plate it would need a flat sub-bed to support it. It occurred to me that a vibrated concrete base finished with a two-part pourable epoxy (as used for for bar tops) could provide this sub-bed.
>
> Alternately I suggest contacting the local tombstone dealer. They often have broken thicker pieces of polished granite lying around. A machinist friend of mine uses a piece of polished granite tombstone for a surface plate. Dial indicator says 0.002"
>
> For all the Gingery projects you need a 24" x 12" x 3" size surface plate at most. "Real" surface plates are usually 3" to 4" thick. Big ones are even thicker.
>
>
> --- In gingery_machines@yahoogroups.com, "james" <james122964@> wrote:
> >
> > Hi everyone,
> > My name is Jim.
> > I am looking to start building the lathe and have a couple of questions before I start.
> >
> > 1. Is there any difference or does it matter if I use zinc die casting alloy instead of aluminum?
> >
> > 2. I have read that granite counter top material is flat to greater than .001 inch can I use such for the surface to scrap in my parts?
> >
> > thanks
> > jim
> >
>
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