My new 3,500 lb cast iron precision work table

[TXNinAZ]

I don't post much on here but figured people would like to see my new table.

I'd been wanting a better work surface for TIG welding and general inspection and found this beauty at an auction. 48" x 120" x 4.25" so I'm estimating the weight at about 3,500 lbs. It's webbed cast iron and precision machined with an inspection cert from 2020 showing it is true within .0046" across the whole top. Not exactly a pink Starrett granite plate, but pretty damn flat.

Used my precision levels to get it within .0001"/foot of level and cleaned up. The timing to get it wasn't ideal since I don't have enough room for it, but I rearranged everything and made it work. Got my building permit for the 900 sq ft shop extension this week though, so soon enough it'll be easier to use.

 

[Iridium rand]

That’s a beauty! But also have to ask, What would such a precision and insanely heavy table like this be used/needed for? I imagine it wasn’t cheap and you need one like this for a specific purpose

 

[PCustoms]

Your cert is from 2019, it expired in 2020.

Piece of scrap you've got there.

(Just my jealousy speaking)

 

[TXNinAZ]

That’s a beauty! But also have to ask, What would such a precision and insanely heavy table like this be used/needed for? I imagine it wasn’t cheap and you need one like this for a specific purpose

I could certainly live without it, but I'd been looking for a cast iron table for a long time and I won't miss any mortgage payments over buying this so I figured why not. With the price of new materials skyrocketing I wouldn't have done much better getting a 1" thick steel plate Blanchard ground and put on a stand, so what the heck.

 

[TXNinAZ]

Your cert is from 2019, it expired in 2020.

Piece of scrap you've got there.

(Just my jealousy speaking)

Lol well, yeah ok, it was issued in 2019 and effective for about half of 2020. Sheesh! Lol

 

[MushCreek]

Nice table! I went to Moore Special Tool for a jig grinding class. They exclusively used cast iron for their precision surface plates. They claimed that granite could absorb moisture and move very slightly.

 

[Renegade1LI]

That is one really nice table! You get a You **** for that one, great find and enjoy.

 

[theoldwizard1]

Anything you are going to weld on top of is NOT going to be useful as an inspection table for long !

 

[mike93lx]

thankfully it has spot below to add some real weight to it. don't want it moving around when you are beating on stuff on top of it!

 

[Stobal]

It’s beautiful!!!

 

[Duker]

Very nice….!

 

[dr_clyde]

Anything you are going to weld on top of is NOT going to be useful as an inspection table for long !

Eh, you'd be surprised. Large pieces of iron are surprisingly resilient.

I highly doubt the OP is going to be using this as a CMM base or something. With proper maintenance and care, you can still use height gages and indicators with a high degree of accuracy on a table that is used as a light welding table.

Don't use it as an anvil. Don't try to weld to it. Avoid grinding on it and take care of burrs and spatter with a flat stone.

 

[TXNinAZ]

Nice table! I went to Moore Special Tool for a jig grinding class. They exclusively used cast iron for their precision surface plates. They claimed that granite could absorb moisture and move very slightly.

Oh wow that would be a dream come true. I think if I had the choice I'd take a scraping class with them, but learning their method for jig grinding would be amazing.

Eh, you'd be surprised. Large pieces of iron are surprisingly resilient.

I highly doubt the OP is going to be using this as a CMM base or something. With proper maintenance and care, you can still use height gages and indicators with a high degree of accuracy on a table that is used as a light welding table.

Don't use it as an anvil. Don't try to weld to it. Avoid grinding on it and take care of burrs and spatter with a flat stone.

Indeed they are. I specifically mentioned TIG welding- very controlled, clean, and no massive heat input through the workpiece. I've already used my precision ground stones to remove all burrs and cleaned it up and it's extremely smooth and flat. I've got some long parallels- maybe I'll stick them end to end and run a surface gage on top of them and an indicator on the table to see how consistent the table is...

 

[Maxcustody]

Please forgive my ignorance on this............................outstanding table, but what is such a table used for in relation to inspection? I also googled "pink Starrett granite plate" and they are listed at almost $9,000 for the one I looked at and this is for the slab only???

What do you use these items for?

 

[TXNinAZ]

Please forgive my ignorance on this............................outstanding table, but what is such a table used for in relation to inspection? I also googled "pink Starrett granite plate" and they are listed at almost $9,000 for the one I looked at and this is for the slab only???

What do you use these items for?

No need to forgive you for not knowing something. A granite plate is typically used to inspect parts as a last step before they go out the door. In modern precision machine shops a CMM (coordinate measuring machine- a computer controlled measuring machine) is used which uses a precision granite plate as its base. This table was used at an aerospace composites facility where parts were set down to ensure they were nice and flat before they went on to another process.
I have a small precision granite plate that I use for precise measuring, but this can be used as well- it's just not as flat as the granite. It was 'cheap' enough for me that I can use it for a work surface, layout table, etc. and enjoy something extremely flat. Hope that helps.

 

[Firebrick43]

Nice table! I went to Moore Special Tool for a jig grinding class. They exclusively used cast iron for their precision surface plates. They claimed that granite could absorb moisture and move very slightly.

Moore jig grinders are really nice but that guy was on crack. Cast Iron will move more over time than granite. There is a reason that almost all CMM and alot of precision grinders are on granite bases/frames.

 

[Maxcustody]

No need to forgive you for not knowing something. A granite plate is typically used to inspect parts as a last step before they go out the door. In modern precision machine shops a CMM (coordinate measuring machine- a computer controlled measuring machine) is used which uses a precision granite plate as its base. This table was used at an aerospace composites facility where parts were set down to ensure they were nice and flat before they went on to another process.
I have a small precision granite plate that I use for precise measuring, but this can be used as well- it's just not as flat as the granite. It was 'cheap' enough for me that I can use it for a work surface, layout table, etc. and enjoy something extremely flat. Hope that helps.

Thank you! Learn something new every day, why I love this site...................................

 

[MushCreek]

I saw that tidbit in a book called 'The Foundations of Accuracy', by Mr. Moore himself. The book is an interesting read if you're into really, really precision work, especially done largely by hand. When I toured the Moore plant, they used a shaper to get the ways within .002", 'rough' scraping was .0001-.0002", and THEN it went on to final finishing. Those guys work in millionths of an inch. Not a granite surface plate in the place. Their cast iron plates were made in house. 48" square, and workbench height, all one casting (with a lot of very deep webbing).

 

[Firebrick43]

I saw that tidbit in a book called 'The Foundations of Accuracy', by Mr. Moore himself. The book is an interesting read if you're into really, really precision work, especially done largely by hand. When I toured the Moore plant, they used a shaper to get the ways within .002", 'rough' scraping was .0001-.0002", and THEN it went on to final finishing. Those guys work in millionths of an inch. Not a granite surface plate in the place. Their cast iron plates were made in house. 48" square, and workbench height, all one casting (with a lot of very deep webbing).

I didn't say you couldn't make cast iron surfaces as accurate as granite. Moore surely wanted control and to make his own. OK. But cast iron is not as stable as granite. That is where I question him. If it was you wouldn't have to rescrape machine bases in from movement. But we had to all the time. I have quite a few hours behind my sandvik manual scrapers and biax power scraper.

 

[RoninB4]

Please forgive my ignorance on this............................outstanding table, but what is such a table used for in relation to inspection? I also googled "pink Starrett granite plate" and they are listed at almost $9,000 for the one I looked at and this is for the slab only???

What do you use these items for?

Not ignorance if you ask a question. Cast iron surface plates used to be the norm a few decades ago (before granite surface plates) for a reference surface that was flat. A flat surface became your "zero" for all other measurements and geometric relativity. The OP got a jumbo sized example, most of them are nowhere near as large. The size of the surface plate often needs to be larger than the piece you're inspecting. Having one end of the piece hang off the end throws flatness specifications out the window. There's plenty of times I wished I had a large reference surface like the OP, my largest surface plate (granite) is only 3' x 5' x 4" and it's not large enough for some of the work I do at home.

To the OP- Congratulations, it's a beauty

 

[Maxcustody]

Not ignorance if you ask a question. Cast iron surface plates used to be the norm a few decades ago (before granite surface plates) for a reference surface that was flat. A flat surface became your "zero" for all other measurements and geometric relativity. The OP got a jumbo sized example, most of them are nowhere near as large. The size of the surface plate often needs to be larger than the piece you're inspecting. Having one end of the piece hang off the end throws flatness specifications out the window. There's plenty of times I wished I had a large reference surface like the OP, my largest surface plate (granite) is only 3' x 5' x 4" and it's not large enough for some of the work I do at home.

To the OP- Congratulations, it's a beauty

Thank you Sir!

 

[seber]

Nice table! I went to Moore Special Tool for a jig grinding class. They exclusively used cast iron for their precision surface plates. They claimed that granite could absorb moisture and move very slightly.

Anyone who claims granite swells with moisture has a lot to learn about mineralogy and crystals.

 

[theoldwizard1]

I've already used my precision ground stones to remove all burrs and cleaned it up and it's extremely smooth and flat. I've got some long parallels- maybe I'll stick them end to end and run a surface gage on top of them and an indicator on the table to see how consistent the table is...

Using stones on the surface is the best thing you can do ! Maybe not a "precision" flat surface , but pretty darn good !