Need a source for cast iron plate

[bgolash]

Hi
I was thinking about using a piece of cast iron as a machine work surface. A machinist mentioned that cast iron is not only cast into shapes but also available as plate. I`m looking for something 20 x 33 inches 5/8 or 3/4 thick. I did a search online but can`t seem to locate anything.

Regards Barry

[NC Cams]

If you can't find iron, I'd use some hot rolled alloy (IE 4140) steel - easier to find.

First have it annealed and normalized, preferably while hanging vertically in a neutral salt bath - less chance of warpage. Furnace cool or slow cool as much as possible

Leave in heat for 1 hour per inch of matl thickness. Normallized, it should be Rc 26 or so which is close to cast iron.

Then find someone who can blanchard grind it and who's prepared to shim it to get it flat. You can't just suck it down as it will be flat when you grind it but will spring back when you release it.

[Jarwalcot]

Barry,

I have a customer that might be able to help you out. How far from Atlanta are you? Would you be able to receive the plate COD?

[Ken_Shea]

Here is a supplier,
Shipping cost will be a bit high, unfortunately.
http://www.anchormetals.com/

The majority of expense in grinding is in holding tight tolerances in regards to thickness and flat and parallel.
Likely flat and parallel will be the only critical tolerances, if the thickness is not critical relax that tolerance and save the money.

Ken

[Kevin Taylor]

Barry I buy cast iron and bronz from midwest alloy's in the chicago aera they have round and flat bar or plate and can cut to your dimenson's 800-526-0548 or 815-338-3800 They are verry helpful and give exelent service Good luck Kevin

[Mcgyver]

try to find an old cast iron surface plate or even large lapping plate. you will see that for that thickness its siting on a ribbed box maybe 4 or 5 inches tall or more. I would doubt that a piece that large is going to even support its own weight without sag, hence the ribbed box cast as part of surface plates & lapping plates - not unlike the idea of a torsion box discussed elsewhere herein.

you don't want to just use any old CI, make sure its nice stuff, ie ductile (ever tried machine a piece of crap CI? lol)

it wouldn't surprise me if a slab like that ends up costing more than a used surface plate and the old surface plate is going to be nicely seasoned (while a lot less than steel, CI does have internal stress that work out with aging and temp cycling), only problem with the surface plate is you have to find one!

[Jarwalcot]

Hello - How is it going with the cast plate quest? If you are still looking, the customer I mentioned that might be able to help said he has a couple of smaller peices if they would work. 10" x 14" x 2.625"

He also said that he knows of a place in North Carolina that might be able to help as well. He said it would be okay for me to give you his contact info.

Why don't you give him a call: Randall Hendrix-R&R Machinery 770-780-7536 or RRMC@aol.com. Just mention that JR Walcott gave you the contact info.

Hope this helps...

Good luck,

[bgolash]

Thanks for the source. I just sent off a email. I did get a quote from
Anchor Bronze & Metals, Inc. It was $388 and that did not include shipping.
It also seems they have to slice a 7 thick piece to make a piece 3/4 x 20 x 33.
Since they cut it and may not get a decent cut they supply it at 1 inch.
This also sounded like a expensive addition to the project. Milling or blachard
grounding that much material would push the price of the finished plate too
high. I am also somewhat concerned about the weight of the plate and its
affect on my machine frame. The frame of the machine is alumium I-beam
doubled up and welded. I`m wondering if adding it at the end of the machine
where the support is greatest still might sag the framework. I also priced a
piece of alumium 1 x 20 x 33 and that was $450. I`m not certain
what direction to take with this work surface addition.

Regards Barry

[Jarwalcot]

You know what, you might check around with a couple of these machinery retrofit companies... Those guys will go in and buy up everything in a plant that is closing down just to get one or two peices they really want. A good guy to try is Harry out/up in New York.... www.galleryofmachines.com or Harry@galleryofmachines.com. He just might have something "out back" that might work.

Good Luck,

[Ken_Shea]

Barry,
Kinda a dilemma huh ?
Same here on a lathe I am converting to CNC, just too much money to plunk down on a chunk of steel, not saying it is not worth it, just more then I want to put into it.

Here is what I am going to try, an acquaintance of mine works for a company that installs hi-tech laboratories in universities and labs around the country. He showed me a piece of the material that they use for counter tops, it was about 1" thick (which may rule out the possible use for you). Right off the bat I recognized that this stuff was more like stone then what one would expect from the epoxy resin material it was made from. It is extremely rigid, can be cut or machined with carbide, it is smooth and very flat and he said it cost about $20 a square foot. In my case (1x12x36)that was $60 plus shipping. He is doing a job very soon that he can get a piece for free from what is left over so that is what I am waiting on. If I knew it would work for sure $60 would be a bargain.

Here is the link he sent me on this very product. To me it is worth the wait and the possibility that it may not work, but I think it will work very well for my needs and possibly yours as well.

http://www.epoxyn.com/perform.htm

Just an idea, although it would seem to me to be more likely to work in your application then mine.


Ken

[WhiteTiger]

Have you tried googling for "foundry" and "cast iron"? Lots of hits with locations all over north america and europe. Quite a few seem to have solid and ribbed slab blanks.

If nothing else, I suppose you could keep an eye out for a dead industrial grade table saw. They almost invariably have cast iron tops around your general size range.

If you care to build with smaller stuff, www.mscdirect.com offers 36 inch lengths of ductile iron up to 8" wide and in various thickness. Just plug "iron" into the front page search box.



Tiger

[jashprecision]

I can offer the same to you but I feel the shipping cost upto your destination will be quite expensive.