Cast Iron and Grinding

[Zumba]

I want to experiment a bit with building my own woodworking machines. The hardest part by far, IMO, is fabricating the tops, frankly because I can't make my own castings and I don't have a giant surface grinder.

Does anyone here know of a source of various sized cast iron tables? If I can't find what I need in cast iron, is thick sheet steel a viable alternative?

As for grinding the tops, is there a way to accurately grind a part that's bigger than the capacity of a surface grinder? The part would need to be repositioned halfway through the grinding process. Will the repositioning throw the whole thing off? Accuracy needs to be about 0.003".

Thanks.

[NC Cams]

Find somebody who has a blanchard grinder. These are suited for griding bigger items and will do it relatively quickly and cheaply.

[Rich Carlstedt]

When we built machines within our own shop, we used tables from a company called AMT..they were the largest in the business at one time.
They had all kinds of tables and tops, including Cast iron of different thicknesses. i did a quick search and did not find their home page, but here is a reference from a Engineering mag.
http://www.engineeringtalk.com/news/mie/mie144.html
Maybe you can find it from there. I think they were located in Illinois.

For a quick source, maybe a ordinary CI surface plate will work ?
I saw a bunch of small ones for 25 bucks apiece at the Cabin Fever show this past January.
When I went back to buy one the next day, they were gone !