Machine shops require thicker concrete floors. Yes? No?

[Lelandwelds]

I have known machinists over the years. Often they say things like " a real machine shop would have 10" concrete not like this cheap floor this SOB did".

Is vibration that big a problem for a mill or lathe? Does it decrease accuracy? Slow down feed rate? Where does the diminishing returns kick in? Was that just chest pounding to impress the ignorant? ( And, yes, I am in that group) I lurk on machining forums. Often I dont understand what they're talking about.

 

[Strouty]

I think most is weight, some of those machines will weigh a lot and it is packed in a very small space.

 

[RWorth]

If you are using your machines to do very accurate work, you need them to stay level and square. I use my mill and lathe for building parts that do not have a very fine tolerance so it's not that important. If I was doing critical work I would have to check level and square constantly.

 

[BuffettFan]

The larger the machine, the thicker the base will need to be.
A small lathe or Bridgeport sized mill is fine on a 4" pad, but a large machine will need a much more substantial base, maybe as much as 30 to 40" with rebar and anchors grouted into the base.
One of the large, 1250mm chuck, vertical lathes I was responsible for having installed required 60" of reinforced 5k psi concrete under the main base. Machine weight was 80000lbs.
Larger machines are anchored so they can be tweaked as needed to level and square the ways.
Our ISO statement required our machines to be laser certified bi-annually at an average cost of $1500 per machine.
There were 24 machines in the facility when I left the company.
So, the answer is It Depends.

 

[larry_g]

The standard Bridgeport sized mill, <3000 lb or a 14" lathe would hold up on most 4" floors. If you start getting into 20" + lathes and large boring mills then you have to have the floor to support the job at hand. It is also not uncommon to set heavy equipment on steel plates to distribute the load.

Me I have a ~5" floor in the shop and only get concerned when running in a tracked vehicle, 15k lb crawler or excavator. When doing this I build a plank road from the gravel into the building to prevent point loading. If I had expected this to be a common thing then I would have reinforced the floor as necessary.

lg
no neat sig line

 

[matt_i]

Biggest concern is if you are rigging a machine in with a forklift. A 10k machine with a 12k forklift (which probably weighs 18k by itself) puts a lot of load on the floor where the front tires will be.

I poured 6" thick 4ksi, with 1/2" rebar on 16" centers.

The general rule of thumb when leveling a machine is not to span an expansion joint and rather have it on its own dedicated pad, but its not always that easy to plan life that way.

Imo anything 5k and under is fine on a 4" minimum slab with good underprep (compacted and not poured on sand).

The machines do their best work when the ways are in the same plane.

 

[velillen01]

Cant speak for the concrete. At work, pretty much all our machinery sits on wood block floors. Granted the buildings were built >75 years ago (some >100 years) ago so Im sure it was a much more cost effective solution back then. But they have held up well! Supposedly it is good for the machines too.

 

[Farmall450]

The standard Bridgeport sized mill, <3000 lb or a 14" lathe would hold up on most 4" floors. If you start getting into 20" + lathes and large boring mills then you have to have the floor to support the job at hand. It is also not uncommon to set heavy equipment on steel plates to distribute the load.

Me I have a ~5" floor in the shop and only get concerned when running in a tracked vehicle, 15k lb crawler or excavator. When doing this I build a plank road from the gravel into the building to prevent point loading. If I had expected this to be a common thing then I would have reinforced the floor as necessary.

lg
no neat sig line

You don't want to embed train track so you could trip over it the other 99.9% of the time?

Although it can be useful to weld/anchor to for other things.

 

[Lelandwelds]

The larger the machine, the thicker the base will need to be.
A small lathe or Bridgeport sized mill is fine on a 4" pad, but a large machine will need a much more substantial base, maybe as much as 30 to 40" with rebar and anchors grouted into the base.
One of the large, 1250mm chuck, vertical lathes I was responsible for having installed required 60" of reinforced 5k psi concrete under the main base. Machine weight was 80000lbs.
Larger machines are anchored so they can be tweaked as needed to level and square the ways.
Our ISO statement required our machines to be laser certified bi-annually at an average cost of $1500 per machine.
There were 24 machines in the facility when I left the company.
So, the answer is It Depends.

That's a darn good "it depends". Thanks. I never knew the big stuff weighed that much. Thats a lot of concrete.

 

[EOC_Jason]

As other's have said, the thicker concrete gives rigidity for what the machine sits on. While the machines themselves are quite rigid, especially smaller ones, however when you get to very large / long (think of a lathe that is 12' long), they need a surface that is solid and won't flex. Basically the theory goes if the ground flexes, the machine could flex, and your part could end up being out of spec.

 

[brownbagg]

the machine shop at the shipyard, its slab is a foot thick with double mats of #6

 

[Kevin54]

For a home shop with a mill & a lathe...... 4-5" is more than adequate. Now if you have presses that weigh tons each, and thumping all day long, then yes, you need a thicker floor.

 

[joes169]

For a home machine shop, 5"of floor should be adeqaute.

If you're running a huge machine shop with massive machines and raw product, 8" and thicker is more common.

As other's have mentioned above, if you're running some heavy presses, mills, etc... in the same shop, they should sit on their own foundations and be isolated from each other. We've installed a ton of machine bases through the years, in many different designs, with the biggest being a multi-level pour with the thickest area just over 9' deep. Obviously, this wasn't from a machine you'd use at home.........

 

[Falcon67]

IIRC, the 20 ton CNC stamping press my old company had sat on a separate 36" pad. It still rattled the whole 180,000 sq/ft building when it was firing.

 

[jkeyser14]

The standard Bridgeport sized mill, <3000 lb or a 14" lathe would hold up on most 4" floors. If you start getting into 20" + lathes and large boring mills then you have to have the floor to support the job at hand. It is also not uncommon to set heavy equipment on steel plates to distribute the load.

Me I have a ~5" floor in the shop and only get concerned when running in a tracked vehicle, 15k lb crawler or excavator. When doing this I build a plank road from the gravel into the building to prevent point loading. If I had expected this to be a common thing then I would have reinforced the floor as necessary.

lg
no neat sig line

A Bridgeport weighs less than 3,000 fully optioned. It would be fine on 3' 3000 psi concrete. The floor load would be less than 500 psi.

 

[bullnerd]

My prototrak knee mill was in my garage built in the 50s. Floor was barely over 2", probably less in some spots. Worked fine. Didn't see any difference in running it and the ones in the real shops I've worked in.

Don't let the floor keep you from buying some machine tools and getting into it!

 

[blazemaster83]

I have about 40,000lb of machine in my home shop on a 6" slab. 2 mills, 2 lathes, shaper, grinders, presses, gantry crane and a large planer that weighs prob 15k. It seems to be fine.

 

[larry_g]

A Bridgeport weighs less than 3,000 fully optioned. It would be fine on 3' 3000 psi concrete. The floor load would be less than 500 psi.

Re read what I said, "Bridgeport sized....<3000". Bridgports are a light weight machine but get into a better machine like a Lagun, https://www.lagun.com/core/uploads/FTV-2F_Brochure.pdf , and it weighs in at 2850 lb bare and has a 750 lb table capacity. So 3k is light for the purpose.

lg
no neat sig line

 

[Lelandwelds]

Huh.

The other thing machine operators do is bang on the parts in vises with 2lb deadblow hammers repeatedly.

Half of the machinists defend that. Half make fun of it.

 

[mattygee]

Like others have said it all depends on the machine and I'm sure each mfr. specifies it. The drop hammer shop where I work has footings 60 feet into bedrock.

 

[MushCreek]

I had a shop in a small warehouse complex. The floor was a scant 4", formed with 2X4's. I had an 11,000 lb. CNC mill brought in that sat on 4 very small pads. Not only did it not hurt the floor, but it never went out of level for the 6 years I had it. I fully expected the floor to crack, but it never did. I've never worried about 'normal' machine tools in a home garage.

 

[matt_i]

The other thing machine operators do is bang on the parts in vises with 2lb deadblow hammers repeatedly.

Half of the machinists defend that. Half make fun of it.

The skill is to know when you are seating the part and when you are bouncing it even higher off the precision parallels. Just like a knife can be wielded by a surgeon or butcher, with differing results, so can a hammer.

 

[4 FN 27]

Our shop is 6 inches thick except the Turret Room. There we did 12 inches thick with an 18 inch sand cushion under it. The Machines are grouted to the floor. When they are punching 1/4 in plate it shakes the building.

Our FMS Towers sit on 36 inch thick slabs.

Most of our Machine suppliers spec 6 inches minimum for Press Brakes, Turret Presses and Lasers.

Once and a while you can see the vibration affect of the Turrets punching in the Laser edge. And I can feel my desk vibrating. More so when the Coal Trains go by.

In my past life we had a 600 Ton Punch Press running for years on a 6 inch floor. When they we blanking .074 SST (46 x 3 1/2) I could hear it in the basement of the building next door. The neighbors eventually complained enough they made us move the Stamping Operation. Off to Wisconsin it went.

The home shop is 6 inches.

Follow the Machine Manufacturers guideline and everything will be OK. In the long run it is better to go thicker rather than have to cut and place a specific Pad.

 

[Lelandwelds]

Like others have said it all depends on the machine and I'm sure each mfr. specifies it. The drop hammer shop where I work has footings 60 feet into bedrock.

A for real actual drop hammer? No ****!

My prototrak knee mill was in my garage built in the 50s. Floor was barely over 2", probably less in some spots. Worked fine. Didn't see any difference in running it and the ones in the real shops I've worked in.

Don't let the floor keep you from buying some machine tools and getting into it!

I hope my first is a CNC precision plasma or at least a Hypertherm with the fine detail low amp parts. A CNC key machine would be cool too.

I have a big empty grassy spot where the garage will be.

IIRC, the 20 ton CNC stamping press my old company had sat on a separate 36" pad. It still rattled the whole 180,000 sq/ft building when it was firing.

I used to sell stuff to LTV Oil States Rubber. They have a 100 inch diameter hydraulic cylinder. Impressive (but out of my league for home shop.) ( can you say" space shuttle gantry components "?)

 

[pcmeiners]

As important as the PSI strength and thickness, just as important is the sub base, thickness of the sub base and the compaction. Thickness/PSI strength means little if what is below the crete sinks and creates hollows.
That said a starting thickness of 6" would be my mark with heavier then normal shop equipment, with a proper sub base/compaction .

 

[Lelandwelds]

go thicker rather than have to cut and place a specific Pad.

That is my thinking.

The machinists were talking like it hurt accuracy and it was dumb to spend millions and cheap out over $10k in concrete. It limited future options.

It's the unkown "hurt accuracy" thing I am asking about. How much vibration is OK? In my wildest dreams I will be a small machinist. ( Look, I said machinist with a straight face.)

 

[rsanter]

Depends on what kind of machines and how big they are.
Most machines that will be used in the home shop are fine on 4” or so slabs

Bob

 

[davethorik]

The old shop I worked at, most of the big machines had their own independent foundations, like the Giddings & Lewis HBM, Sip 8000 jig-borer, and Okuma MCVA twin column gantry mill. However some were thrown in as an afterthought...the main shop floor was either 6" or 8" thick, and the 42"×144" Mattison surface grinder cracked it in multiple places. That grinder was a BEAST.

 

[jmarkwolf]

I've got reinforced 4" slab in my shop and it's holding up under my 2200lb Bridgeport and 1000lb lathe with nary a groan.

Not to say you wouldn't need a thicker floor for heavier machines.

 

[GMCGarage]

A slab will only be as strong as your subgrade or subbase.

 

[Lelandwelds]

A slab will only be as strong as your subgrade or subbase.

Two to 15 ft below ground here is solid pink dolomite.

I am not asking about big dumb weight on a slab. Dumb weight I am familiar with. I am asking about accuracy being hurt from some weird harmonic vibrating the cutters.

I have seen 30 inch pipeline wiggle like a cooked spaghetti noodle. I have felt traffic wiggle an overpass like it was a 2 x10 on scaffolding with two fat guys moving around. These machinist talk about clamping pressure distorting parts temporarily. They talk about cutting speeds hurting surface flatness. Some of these guys wouldnt surprise me if they figured in the earths rotational speed or the barometric pressure.

How rigid does a slab need to be for accuracy?

 

[cj7jeep81]

Two to 15 ft below ground here is solid pink dolomite.

I am not asking about big dumb weight on a slab. Dumb weight I am familiar with. I am asking about accuracy being hurt from some weird harmonic vibrating the cutters.

I have seen 30 inch pipeline wiggle like a cooked spaghetti noodle. I have felt traffic wiggle an overpass like it was a 2 x10 on scaffolding with two fat guys moving around. These machinist talk about clamping pressure distorting parts temporarily. They talk about cutting speeds hurting surface flatness. Some of these guys wouldnt surprise me if they figured in the earths rotational speed or the barometric pressure.

How rigid does a slab need to be for accuracy?

How accurate do you need to be If you need to be within tenths, and you are using large machines, I'm sure you need a lot more slab than someone aiming for +/- .005 on a smaller lathe.

 

[Lelandwelds]

How accurate do you need to be If you need to be within tenths, and you are using large machines, I'm sure you need a lot more slab than someone aiming for +/- .005 on a smaller lathe.

Well, I am unsure how stiff a floor I need in a building I havent built yet to hit an accuracy I dont understand with equipment I don't yet own.

It may be a bit premature.

 

[cj7jeep81]

Well, I am unsure how stiff a floor I need in a building I havent built yet to hit an accuracy I dont understand with equipment I don't yet own.

It may be a bit premature.

Yeah, I'd say. I know I don't have nearly enough skill to hit that, and I have old semi-worn out machines, so floor vibration is the least of my concerns. And if you are planning on spending hundreds of thousands of dollars on high-end machines (or getting some 10k pound machines), I'd spend the extra couple grand to make the slab 8" or so. Otherwise, a 4" slab on a good base would be plenty sufficient.

 

[Lelandwelds]

Yeah, I'd say. I know I don't have nearly enough skill to hit that, and I have old semi-worn out machines, so floor vibration is the least of my concerns. And if you are planning on spending hundreds of thousands of dollars on high-end machines (or getting some 10k pound machines), I'd spend the extra couple grand to make the slab 8" or so. Otherwise, a 4" slab on a good base would be plenty sufficient.

I have learned what something closes at auction has little to do with its dollar value. If I get too large, the rigger will cost more than the machine. I am doing some" machining"with a half inch drill and a file or grinder. I sincerely doubt I will approach any high accuracy or volume. I dont know how much I dont know but I am sure it is a lot. Three phase is less than 200ft away in two directions.

My little mechanical iron worker shook the whole slab when running. But between 4" and 8" is a good window.

 

[rk_tek]

I'm just a dumb home gamer, so take this as you wish. For a home shop working on the smaller side of machining and fab, you're probably just fine with a 4" slab. But let's say your 80 gallon compressor starts thumping away in the corner while you have the table on your Bridgeport at the end of its travel when you're facing a long piece of stock. I can see how you could get chatter and inaccuracy. Mass plays a big part, but natural frequencies and harmonics could be negligible, or wreck havoc on things. The Tacoma Narrows Bridge comes to mind.

A factory i used to work in had an 80 ton flywheel press. When we were punching holes in 3/8" SS bar it would shake the whole building. The people in the buildings on either side of us said their coffee cups had ripples in them. That press sat on a 6' deep block of concrete separate from the rest of the slab with rubber strips in the joint and the machine also sat on isolation pads bc the feet started wearing into the floor.

 

[matt_i]

Well, I am unsure how stiff a floor I need in a building I havent built yet to hit an accuracy I dont understand with equipment I don't yet own.

It may be a bit premature.

A "smaller" lathe, lets just throw out the under 40" between centers is going to be limited by its own structure long before the concrete base gets involved.

You get up above 72" between centers, and above 10k then imo you are into the territory where you need to consider advanced concrete.

For recreational use (iow not already having a stable full of machinery) just pour a 4" minimum and worry about other things in life.

 

[Lelandwelds]

I'm just a dumb home gamer, so take this as you wish. For a home shop working on the smaller side of machining and fab, you're probably just fine with a 4" slab. But let's say your 80 gallon compressor starts thumping away in the corner while you have the table on your Bridgeport at the end of its travel when you're facing a long piece of stock. I can see how you could get chatter and inaccuracy. Mass plays a big part, but natural frequencies and harmonics could be negligible, or wreck havoc on things. The Tacoma Narrows Bridge comes to mind.

A factory i used to work in had an 80 ton flywheel press. When we were punching holes in 3/8" SS bar it would shake the whole building. The people in the buildings on either side of us said their coffee cups had ripples in them. That press sat on a 6' deep block of concrete separate from the rest of the slab with rubber strips in the joint and the machine also sat on isolation pads bc the feet started wearing into the floor.

LTV had a plant with a 100 inch hydraulic cylinder running a press. Just the pumps shook the entire buildings slab. I want to ask the dumb questions before I break ground.