Why cast iron?

[Nick Shattuck]

Why are power tool tables made out of cast iron and not some other material such as granite or marble? Is it due to cost or that the rock may chip? Cast iron is notorious for rusting and granite is easier to make flat, so why do manufacturers not use something like granite for this purpose?

[Grant Aldridge]

I'mma go ahead and say COST and durability.

[Andrew Seemann]

It's heavy, dampens vibration, and get this... you easily can cast it into whatever shape you want it. It is quite strong for its weight and is easy to machine.

[Tim Janssen]

A Company named Steel City makes table saws with granite tops. Why not more choices. Could have something to do with attaching components. Or not enough manufacturers see the benefit of changing, Who knows!
Cheers,

Tim

[Ken Fitzgerald]

Mass.....reduces vibration resulting in more accuracy. Is Steel City still in business? There have been reports that granite tops fail due to stress cracks. Myself, I prefer cast iron.

[Brian Nguyen]

Steel City went out of business a few years ago.

Wasn't one of the Craftsman zip code TS made with granite for wings as well? Probably came out of the same factory as the Steel City saws so....

[Martin Wasner]

Cheap, durable, you can cast just about anything, you can machine it, soaks up vibration.

[Wayne Lomman]

Cast iron is, as Andrew said, easy to cast into shape and easy to machine. My day job is with an CNC machining workshop and we happen to have a foundry as well. Cast iron is easy to cast and the machinists love the rare job they get with it because it machines so easily. These two factors alone make it economical while still being robust. Stone, on the other hand, cannot be threaded unless you bond metal inserts in place, is subject to chipping and fracturing and has no tensile strength. We do have a granite bed on our co-ordinate measuring machine because it is a stable surface for this use ie, lay a completed component on it and set the computer to check all your dimensions for compliance using a range of probes and technologies. Also, granite is not as easy to get flat a might be thought. The easiest materials to flatten are of uniform consistency. Cast iron is a good example of this. Cheers

[Brian Holcombe]

Granite doesn't hold bolts well and machine tables need to be bolted onto their respective machines. In some cases they carry motors and fences, so there would be an incredible failure rate.

Edit: Sorry, Wayne beat me to it.

[Aaron Rosenthal]

I have one of the Rigid Home Depot granite top saws. It works fine, never really had a problem has a built in mobile base. It's probably 6 years old or more ( I don't remember) but except for the lack of power, does the job.
It sits in my garage in rainy, damp Vancouver Canada, and it's one tool I don't have to work at combatting rust.

[Mike Cutler]

As others have stated, cast iron has a lot of positives. It's just a good material choice.
One thing I've always wondered is why we keep it bare. That's where most of the rust issues come from.
I've often though about bluing the tops of my cast iron surfaces, or just painting them. Haven't done it yet, but I think about it from the to time.

[Frederick Skelly]

One thing I've always wondered is why we keep it bare. That's where most of the rust issues come from. I've often though about bluing the tops of my cast iron surfaces, or just painting them. Haven't done it yet, but I think about it from the to time.

An aside. I'm trying an experiment sorta like what Mike mentions right now. I wiped one machine top down with with poly and another with dewaxed shellac. Initial results indicate the poly lasts longer. We'll see.

Fred

[Nick Decker]

Fred, I ran across a video on YouTube by a guy who did his saw top with poly. My first thought was the problem of poly adhering to most things, including itself. I think I'll just stick to wax.

Painting a machined cast iron surface just feels....wrong.

[Marshall Harrison]

Steel City went out of business a few years ago.

Wasn't one of the Craftsman zip code TS made with granite for wings as well? Probably came out of the same factory as the Steel City saws so....

Don't know about Craftsman but Rigid had a table saw with a granite top (model #4511). They were discontinued due to a problem with the arbor breaking.

Tough to use magnet feather boards etc. on granite.

[Lee Schierer]

If you drop a hammer or miter gauge on a cast iron top, the worst that happens is you get a small dent. If you do that on granite, you could end up with two pieces.

[Cary Falk]

One thing I've always wondered is why we keep it bare. That's where most of the rust issues come from.


Wasn't it also Steel City that offered titaninum nitride coated tables before they went out of business? I wonder how long the thin layer would last under constant use. I just put T9 and wax on my cast iron and it works good enough in rainy Portland, OR metro area.

[Mark Hennebury]

I rebuild a lot of old cast iron woodworking machines, after all is done i wipe the raw cast surfaces with boiled linseed oil and turps.

[Mark Hennebury]

Although maybe not as versatile in some instances and also probably not as cost effective, there are some pretty serious machines that are granite based, some are solid granite some are molded from granite aggregate and epoxy resin.

382598 382599

Hembrug From Holland have been in business a long time and years ago made some very nice standard metal lathes, and tool and cutter grinders, i had one of the tool and cutter grinders.They now make Ultra high precision lathes based on granite. http://www.hembrug.com/


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Kugler From Germany make ultra high precision lathes, fly cutters and milling machines. https://www.kugler-precision.com/index.php?precision-machines-EN


https://youtu.be/niop1HkuzdY



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[Mark Hennebury]

This is a very nice "home made" granite lathe.

https://youtu.be/sFrVdoOhu1Q

[Jim Becker]

Cast iron brings a lot of advantages...it has great mass to reduce vibration, machines easily because it's not terribly hard but is still very durable, holds fasteners well and lasts a long time with proper care.

[Brian Holcombe]

This is a very nice "home made" granite lathe.

https://youtu.be/sFrVdoOhu1Q

That is really cool!

[Mark Hennebury]

That is really cool!

That guy is pretty cool, he has a bunch of videos, all quite interesting. By the way that's his basement workshop.

[Brian Holcombe]

That guy is pretty cool, he has a bunch of videos, all quite interesting. By the way that's his basement workshop.

I got a good laugh out of his line about how making one of those was pretty easy, though he seemed to mean that quite genuinely.

[Mark Hennebury]

I got a good laugh out of his line about how making one of those was pretty easy, though he seemed to mean that quite genuinely.

Easy is not the first word that springs to mind; fascinating project to consider. I think that besides the knowledge you would need some serious equipment. I would love to see a video of it being made.
But it definitely gets your mind thinking that maybe you could make something using some of the systems that he used.

[johnny means]

This is a very nice "home made" granite lathe.

https://youtu.be/sFrVdoOhu1Q

"Granite" lathe is a bit of a stretch.

[Tim Janssen]

Steel City machinery still being made by a company in Quebec, Canada.
Made in Taiwan though. Interesting!
https://www.steelcitymachines.ca/company/about-us.html



(https://www.steelcitymachines.ca/company/about-us.html)

[Chris Fournier]

Cast iron rust? Sure but not like steel. No biggie. The granite gig is fine for memorials, surface plates, and counter tops. I'd never want it for a machine working surface.

[Bill Dufour]

Big problem is going to be the thickness needed to give adequate strength. I had a 1" thick marble slab on my RAS outside for cutting firewood and framing a shed. Dropped a 2x4 on it a few inches and it cracked. A standard 10" table saw would be lucky to have the blade come above the surface since the top slab would need to be 2-4 inches thick. Also stone and iron will move different amounts with temperature swings so they can not be firmly attached or the stone will crack or the metal bend and either way you lose the accurate setup and must adjust/recalibrate every time the temp changes.
Bil lD

[Brian Holcombe]

Easy is not the first word that springs to mind; fascinating project to consider. I think that besides the knowledge you would need some serious equipment. I would love to see a video of it being made.
But it definitely gets your mind thinking that maybe you could make something using some of the systems that he used.

Absolutely, it's highly encouraging. I'm impressed by how stout it is, but actually seems considerably smaller scale that what I would have imagined to be required for making cylinders with a 1 micron slip fit.

[Brian Holcombe]

"Granite" lathe is a bit of a stretch.

I see a granite bed on the lathe, don't you?

[Bill Dufour]

I see a granite bed on the lathe, don't you?

The only part made of stone has no moving parts. All the moving parts are iron or steel. I notice he has no lead screw or even gears. I suppose stepper motors and cnc have replaced most of the tricky bits.
Reminds me of the glass snowboard someone had made. It worked okay until it didn't.
Bill D.

https://www.youtube.com/watch?v=vmZ1QfZ9Skk

5:00 they start to ride.
(https://www.youtube.com/watch?v=vmZ1QfZ9Skk)

[Mark Hennebury]

The only part made of stone has no moving parts. All the moving parts are iron or steel. I notice he has no lead screw or even gears. I suppose stepper motors and cnc have replaced most of the tricky bits.
Reminds me of the glass snowboard someone had made. It worked okay until it didn't.
Bill D.

https://www.youtube.com/watch?v=vmZ1QfZ9Skk

5:00 they start to ride.
(https://www.youtube.com/watch?v=vmZ1QfZ9Skk)

The OP asked:

"Why are power tool tables made out of cast iron and not some other material such as granite or marble?"

I was simply answering the question.

Many machine tables are made of granite.

Many of the other components, such as bases, columns and bed ways are also made of granite.
I showed a few of the ways in which granite has been used in various machines.
I did in no way make any attempt to say that granite was in all ways superior to cast iron, or that it could be used to replace all of the parts made of cast iron.

[Bill Dufour]

Not saying the lathe wasn't granite. it is interesting to see it. thanks for posting. This whole thread reminds me of the concrete ships made in WW1. Some of which are still afloat. One was beached near Santa Cruz California and turned into a dance hall then a fishing pier. I think it is too broken up to step on these days. One of its sister ships is still afloat in British Columbia as a harbor protection wall for a lumber mill. So this is wood related:) They were described as good solid ships until they hit something then the broke apart like a dropped tea cup.
Bil lD.

[Brian Holcombe]

I’ll be sure an avoid naval conflicts with a granite lathe. I might be able to avoid using one for trench warfare as well.

[Mark Hennebury]

Not saying the lathe wasn't granite. it is interesting to see it. thanks for posting. This whole thread reminds me of the concrete ships made in WW1. Some of which are still afloat. One was beached near Santa Cruz California and turned into a dance hall then a fishing pier. I think it is too broken up to step on these days. One of its sister ships is still afloat in British Columbia as a harbor protection wall for a lumber mill. So this is wood related:) They were described as good solid ships until they hit something then the broke apart like a dropped tea cup.
Bil lD.

I don't have a problem with anyone trying something new, don't have any problem with failures, that is all part of learning and progress.
I saw some concrete boats when i was in Newfoundland back in the 70's or 80's Done as an experiment, I don't know anything more about them.

I saw the lathe / grinder video a year or two, not sure when exactly, but i found it quite fascinating and to me its a brilliant piece of work in both concept and execution, and an inspiration that opens up your mind to possibilities of new construction methods with incredible accuracy, and possibly within reach of a small machine shop, with purchasing many off the shelf parts. I recently got a quote to get my lathe bedways machined, and it was several thousand dollars and the tolerances were in a couple of thou, not micron. Plus of course i have to dismantle, crate and ship a machine that weighs several thousand pounds.
To me that video of the the lathe was brilliantly inspirational, especially since i already have a couple of large air bearings and an 8' granite surface plate on which to assemble projects, so it got me thinking.

[Bill Dufour]

They did do some experiments with big aircraft carriers made of reinforced ice during WW2.
Bill D.

https://en.wikipedia.org/wiki/SS_Palo_Alto

https://en.wikipedia.org/wiki/SS_Peralta

[Ben Rivel]

Cast iron is just better ;)

[johnny means]

I'm thinking the biggest advantage of cast iron from a manufacturers standpoint is the "cast" part. I'm betting that if you had to machine iron components from a slab cut from the middle of a mountain, it wouldn't be nearly as ubiquitous.

[Mark Hennebury]

I'm thinking the biggest advantage of cast iron from a manufacturers standpoint is the "cast" part. I'm betting that if you had to machine iron components from a slab cut from the middle of a mountain, it wouldn't be nearly as ubiquitous.

Cast Granite.
382760

[johnny means]

Cast Granite.
382760

What are we looking at?

[Mark Hennebury]

What are we looking at?

Cast granite. granite particles and epoxy cast in a mold.

https://youtu.be/bL-psmFPaoY

[johnny means]

Cast granite. granite particles and epoxy cast in a mold.

https://youtu.be/bL-psmFPaoY

Oh,concrete��

[Peter Christensen]

Not concrete. Closest approximation would be Super Corian.

[Mark Hennebury]

Oh,concrete😁

Concrete is not so bad.
The Pantheon (https://en.wikipedia.org/wiki/Pantheon,_Rome) in Rome (https://en.wikipedia.org/wiki/Rome) is an example of Roman concrete construction.

382809

[Bill Dufour]

In California most of the new concrete work I see has about 50% rebar inside the concrete. This is for structural stuff not sidewalks and simple foundations.
Which dome was being built and Leonardo added a big chain around the base so it would not fall? maybe florence?
Bil lD.

[Brian Holcombe]

That was the Duomo in Florence, also known as Florence cathedral.

The Pantheon is more than 1000 years prior.

[johnny means]

Nothing wrong with concrete. It's quite a remarkable material.

I think concrete is a better description than super corian. Corian is totally man-made, basically it's just the epoxy. Concrete is sand, gravel, and stone aggregate with a binding agent.

[Peter Christensen]

Corian is actually quartz and a resin, Acylic I believe, so granite and epoxy is up another level.

[Keith Weber]

There is a video I've seen and wish I could find it that answers the OP's question as to why cast iron is used for tool tables instead of granite. I think it was a beer commercial or something like that. It shows a bunch of guys standing around a nice, expensive kitchen with a huge island with a granite top. One of the guys realizes his beer is not a twist off, so he holds the lip of the bottle cap on the edge of the granite top and gives it a whack with his other hand to open his beer. I think his beer opened, but about a 5" x 5" corner chunk of granite breaks off and lands on the floor. Awkward silence! LOL! That is why granite tables aren't used for tools!

[johnny means]

Corian is actually quartz and a resin, Acylic I believe, so granite and epoxy is up another level.
Sorry, you've got Corian mixed up with other solid surface materials. Dupont's Corian is absolutely all man made. Dupont did create Zodiac Quartz which was at some point rebranded as Corian Quartz.

[Peter Christensen]

I sit corrected Johnny. :)

[Bill Dufour]

Hard to believe that modern concrete is only about 150 years old. It was a trade secret that dies with the Roman Empire and was figured out around 1840.
The first reinforced concrete bridge was not built until 1889 and it is still used today in Golden Gate Park in San Francisco California, USA

[Mark Hennebury]

The days of traditional cast iron may be numbered.



https://youtu.be/pBmLHDANDKM

[Mark Hennebury]

More 3D


https://youtu.be/BnBMN0zgB10

[Carlos Alvarez]

I really lusted for a Steel City granite TS. An acquaintance bought one. Recently I got to see the big crack in it from the time he dropped a tool and it stress-cracked. My old Unisaw cast iron top was rusty as hell when I bought it cheap, but some love with a die grinder and wheel made it like new. His granite will never be like new. I think that answers the question.

Also Steel City is out of business.

[Andrew Joiner]

Wow, Additive Manufacturing is amazing. At first I heard " 60 hrs to make a part" and "8 hours to cut it from the base" so why do it? Then the second video " the turbine engine made with additive manufacturing has 1 key part that used to consist of over 300 parts. All 300 parts would wear and leak as they aged."Alie Ward is cool too.

Mark,thanks for the videos.

[Mark Hennebury]

Wow, Additive Manufacturing is amazing. At first I heard " 60 hrs to make a part" and "8 hours to cut it from the base" so why do it? Then the second video " the turbine engine made with additive manufacturing has 1 key part that used to consist of over 300 parts. All 300 parts would wear and leak as they aged."Alie Ward is cool too.

Mark,thanks for the videos.

Andrew, i love cast iron and have many old machines in my shop from the 50's, but it is still fascinating to see what else is being developed. Additive manufacturing is the emerging technology and it will be interesting to see where it goes.